Micro doi: 10.3390/micro6020042

Authors: Afia Sultana Qingyue Wang Miho Suzuki Christian Ebere Enyoh Md. Sohel Rana Weiqian Wang Anunobi Chinazo Ndidiamaka

Microplastic (MP) contamination in terrestrial ecosystems has emerged as a critical environmental concern, particularly in agricultural soils influenced by anthropogenic activities. This study investigated the depth-wise distribution, polymer composition, and associated ecological and human health risks of MPs in homestead agricultural soils across four regions of Bangladesh representing different levels of industrialization: Narayanganj (old industrial), Savar (moderate industrial), Gazipur (emerging industrial), and Mymensingh (non-industrial). Soil samples were collected from two depth intervals (0–20 cm and 21–50 cm), and MPs were extracted using density separation, identified through microscopic analysis, and characterized via ATR-FTIR spectroscopy. A diverse range of MP morphologies and polymers was detected, with irregular particles and fragments dominating the composition. Polypropylene (PP), high-density polyethylene (HDPE), and polyethylene terephthalate (PET) were the most abundant polymers, reflecting widespread domestic, industrial, and agricultural plastic usage. MP abundance was consistently higher in surface soils, indicating dominant surface inputs, although vertical migration into subsoil layers was evident. Spatial analysis revealed higher MP contamination in industrial regions, particularly Narayanganj and Savar, compared to the non-industrial reference site. Ecological risk assessment indicated low risk levels across all regions; however, significant spatial variability was observed. Human exposure assessment demonstrated that inhalation was the primary pathway, followed by dermal contact and ingestion, with children exhibiting higher exposure levels than adults. Lifetime average daily dose (LADD) and carcinogenic risk estimates remained below acceptable thresholds, suggesting minimal immediate health risks. Nevertheless, the persistence, mobility, and cumulative nature of MPs highlight potential long-term concerns. Therefore, this study provides comprehensive insights into the sources, distribution, and risks of MPs in homestead agricultural soils and underscores the need for improved waste management practices, sustainable agricultural strategies, and long-term monitoring to mitigate environmental and human health impacts.

Micro doi: 10.3390/micro6020041

Authors: Rebecca Sikkema Igor Zhitomirsky

This investigation addressed challenges in the delivery of poorly soluble drugs, and the colloidal processing of polymer–ceramic composites by fabrication of advanced supramolecular hydrogels. Polygalacturonic acid (PGA) polymer and 18β-glycyrrhetinic acid (GA) drug, both characterized by poor aqueous solubility, were selected as model building blocks for supramolecular hydrogels. Meglumine (MG) served as a multifunctional component in the gels, acting as a building block as well as an alkalizing and solubilizing agent for PGA and GA. Investigations revealed gel formation mechanisms, which were based on the electrostatic interactions of deprotonated anionic carboxylic groups of PGA and GA with protonated amino groups of MG and the hydrogen bonding of PGA polymer and GA molecules. The feasibility of the fabrication of PGA-MG and GA-MG gels opened an avenue for the fabrication of PGA-GA-MG gels. The composite gels provided a platform for drug delivery, and the kinetics of drug release from the composite gels containing MG excipient were investigated. Composite gels were obtained from colloidal dispersions, containing bioceramics, such as hydroxyapatite, silica, and titania, and bioglass in the PGA solutions in the presence of MG. The results of this investigation pave the way for the fabrication of novel supramolecular and composite gels loaded with various functional materials.

Micro doi: 10.3390/micro6020040

Authors: Edith Dube

Phytochemical-assisted green synthesis of silver nanoparticles offers a sustainable alternative to conventional fabrication routes by utilising plant-derived metabolites as multifunctional reducing, capping, and stabilising agents. Polyphenols, flavonoids, tannins, alkaloids, and related biomolecules mediate the reduction of Ag+ to Ag0 under mild conditions while controlling nucleation, growth, and surface stabilisation, thereby dictating nanoparticle size, morphology, and colloidal stability. This review establishes clear links between phytochemical composition and the mechanistic pathways governing nanoparticle formation and biofunctional performance. Variations in extract chemistry influence electron transfer dynamics, surface functionalisation, and physicochemical properties, ultimately modulating biological activity. Enhanced antimicrobial and antioxidant effects arise from synergistic interactions between the silver core and phytochemical capping layers, promoting membrane disruption, reactive oxygen species generation, and biomolecular interference. Despite promising applications in antimicrobial coatings, food preservation, agriculture, and anticancer systems, key challenges remain, including compositional variability, limited mechanistic standardisation, and insufficient toxicological evaluation. Nonetheless, phytochemical-assisted synthesis provides a tunable and sustainable platform for AgNP production, aligning nanomaterial design with green chemistry principles while enabling multifunctional bioactivity. By integrating phytochemical composition, mechanistic synthesis pathways, and structure–activity relationships across diverse applications, this review provides a critical framework for the rational design, standardisation, and scalable development of next-generation phytochemical-mediated AgNP systems.

Micro doi: 10.3390/micro6020039

Authors: Hedi Ben Ahmed Maxim Pryazhnikov Jessica Pirogovskaya Sergey Zharkov Il’ya Bril’ Andrey Minakov

Magnesium oxide (MgO) nanoparticles, recognized for their versatile applications from catalysis to biomedicine, require synthesis methods that offer precise control over their properties while ensuring safety and scalability. This study explores a safer, industrially viable adaptation of the polyacrylamide gel synthesis route by utilizing magnesium sulfate (MgSO4) instead of conventional nitrates to mitigate explosion risks during calcination. A systematic study was conducted to evaluate the influence of key synthesis parameters, such as crosslinker ratio, initiator concentration, precursor loading, calcination conditions (including temperature, time, and heating rate), pH, and the use of chelating agents (EDTA and citric acid), on the purity, morphology, size distribution, and colloidal stability of the synthesized MgO nanoparticles. Characterization via X-ray spectroscopy XRF and XRD, acoustic spectroscopy, nitrogen physisorption (BET), electronic microscopy SEM and TEM and dispersion stability analysis revealed that polymeric cell volume (controlled by crosslinker and initiator) significantly influences size distribution, while chelating agents in alkaline environments drastically reduce particle size to ~20 nm and alter morphology to platelets (EDTA) or polygonal shapes (citric acid). Crucially, a low heating rate (2.5 °C/min) was found to yield smaller particles (~30 nm) and higher purity. This work provides a comprehensive blueprint for the tailored, safe, and scalable synthesis of MgO nanoparticles with targeted properties for specific technological applications.

Micro doi: 10.3390/micro6020038

Authors: Emanuela Cutuli Pasquale Memmolo Biagio Mandracchia Maide Bucolo

This work presents the Smart-Reflex-Scope, a compact and accessible smartphone-based microscope with integrated reflective illumination developed for on-chip analysis of microparticle dynamics. In this work, the platform is specifically employed to characterize size-dependent microparticle motion within a microchannel. The Smart-Reflex-Scope simultaneously functions as an illumination source and imaging unit by integrating a reversed smartphone camera lens, a custom reflex module, a microfluidic chip, and a precision Z-axis translation stage for focal adjustment. The optical performance was quantitatively evaluated in terms of equivalent focal length, magnification, and object-plane spatial resolution, providing a comprehensive assessment of the system’s microscale imaging capabilities. A comparative design study was conducted between two configurations: Design-1, based on normal reflection, and Design-2, based on angular reflection. The two approaches were analyzed with respect to illumination uniformity and imaging performance to identify the optimal configuration for enhanced visualization. Experimental validation was performed using synthetic microparticles with diameters of 6μm and 20μm, enabling assessment of the system’s ability to resolve and dynamically track micrometric objects of different sizes. The results demonstrate reliable detection and size-dependent dynamic characterization. A two-factor statistical ANOVA analysis confirmed the significance of the observed differences between microparticle groups under the tested experimental conditions (p-value <0.0001). Overall, the proposed platform represents a scalable and miniaturized microscopy solution bridging conventional benchtop instruments and portable analytical devices.

Micro doi: 10.3390/micro6020037

Authors: Masanori Sakamoto Akari Nakata Misa Shimizu Ayuka Tagashira Hideyuki Hirazawa Yugo Imai Hazuki Saka Kokona Okabe

Conventional organic and inorganic ultraviolet (UV) filters often face limitations related to photostability, skin penetration, and potential toxicity arising from their photocatalytic activity. In this study, graphitic carbon nitride (g-C3N4) was investigated as a candidate biocompatible UV-shielding pigment. g-C3N4 powders were synthesized via thermal polymerization using urea and melamine as precursors. The melamine-derived samples exhibited a dense, block-like morphology with a strong yellow coloration and poor spreadability. In contrast, the urea-derived samples formed a distinctive porous and rounded structure. This morphology, originating from multistage gas evolution during polymerization, significantly reduced the static friction coefficient, resulting in a smoother texture and improved skin adaptability. Preliminary biological evaluation indicated high cell viability in cytotoxicity tests. Combined with the observed low photocatalytic activity, these findings suggest a favorable biocompatibility profile for topical applications. Overall, the results demonstrate that precursor engineering using urea enables the synthesis of high-performance g-C3N4 pigments with improved texture, desirable optical properties, and reduced biological reactivity.

Micro doi: 10.3390/micro6020036

Authors: Manita Saini Syed Arman Rabbani Mohamed El-Tanani Shrestha Sharma Rakesh Kumar

Fungal infections remain a major and growing global health concern, particularly in immunocompromised populations and in settings where antifungal resistance is increasing. Imidazole antifungals continue to play an important role in the treatment of superficial and mucocutaneous mycoses because they inhibit lanosterol 14α-demethylase (CYP51), a key enzyme in ergosterol biosynthesis. This mechanism disrupts fungal membrane integrity and underlies their clinical utility. However, the effectiveness of imidazoles is increasingly limited by resistance mechanisms such as CYP51 mutations, efflux pump overexpression, and biofilm-associated tolerance. In parallel, several biopharmaceutical constraints, including poor aqueous solubility, limited tissue penetration, short residence time, and variable local drug exposure, further reduce therapeutic performance. This review critically examines the medicinal chemistry, mechanism of action, and resistance biology of imidazole antifungals, while also highlighting the role of pharmacokinetic and pharmacodynamic limitations in treatment failure. Particular attention is given to emerging drug delivery approaches, including lipid-based systems, vesicular carriers, nanocarriers, and other advanced topical formulations, which are being developed to improve solubility, enhance tissue retention, and sustain antifungal exposure at the site of infection. By integrating resistance mechanisms with formulation science, the review provides a translational perspective on how imidazole antifungals may be optimized for improved clinical utility and resistance management.

Micro doi: 10.3390/micro6020035

Authors: Tomasz Blachowicz Guido Ehrmann Johannes Fiedler Reinhard Kaschuba Andrea Ehrmann

Freeform optics belong to the increasingly important elements in optical research and industry, which pose several challenges regarding design and highly precise manufacturing. First being used in cameras and for focusing, nowadays freeform optics are used in a broad range of applications, from lighting to LiDAR, from endoscopy to photovoltaics, and from astronomical instruments to quantum cryptography. Designing freeform optics can be based on different theories and methods. Fabrication is possible by mechanical methods, such as diamond turning or high-precision milling, often followed by different polishing techniques, as well as laser-based techniques, mainly applying different lithographic techniques. Here, we give an overview of recent design and optimization methods, production methods used during the last years, and applications of freeform optics, including the possibility to combine freeform optics with tunability for different applications. We describe the opportunities of new applications as well as common problems and give an outlook towards future directions of research and development.

Micro doi: 10.3390/micro6020034

Authors: Vladimir Georgiev Evgeni Ivanov Todor Batakliev Rumiana Kotsilkova

The present work investigates the composition-dependent thermoresistive behavior of polylactic acid/polycaprolactone (PLA/PCL) composites reinforced with 4 wt.% graphene nanoplatelets (GNP), prepared by twin-screw extrusion at PLA/PCL ratios of 95/5, 70/30, 60/40, and 30/70 wt.%/wt.%. Their morphology, thermal properties, and structure were characterized by scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and wide-angle X-ray diffraction. Thermoresistive measurements over four cycles (30–130 °C) revealed two distinct regimes: PLA-rich compositions exhibited a stable, monotonic positive temperature coefficient (PTC) response after the first conditioning cycle, with TCR values up to 0.38% °C−1, whereas compositions with 40–70 wt.% PCL displayed a non-monotonic PTC-to-NTC transition linked to PCL melting and subsequent conductive network rearrangement. The magnitude of both PTC and NTC responses increased systematically with PCL content. These results demonstrate that the thermoresistive characteristics of biodegradable PLA/PCL/GNP composites, including the sign, magnitude, and switching temperature of the TCR, can be effectively tuned through blend composition, offering a practical route for designing thermally responsive sensing materials.

Micro doi: 10.3390/micro6020033

Authors: Diego Pádua de Almeida Paula Zambe Azevedo Ramila Cristiane Rodrigues Elisa de Paula Reis Lima Paulo Cesar Stringueta Pedro Henrique Campelo Evandro Martins

The increasing incidence of foodborne diseases and the limitations of conventional preservation methods have driven the search for safer, more effective, and sustainable antimicrobial strategies. In this context, essential oil nanoemulsions have emerged as promising alternatives to synthetic preservatives due to their broad-spectrum antimicrobial activity, natural origin, and potential applicability across diverse food matrices. This study critically examines the mechanisms of action of essential oils against pathogenic and spoilage microorganisms and discusses how their incorporation into nanoemulsions can overcome limitations such as low volatility, poor solubility, and chemical instability. The physicochemical principles governing the formation and stability of these nanoemulsions are addressed, alongside the influence of food matrix components (proteins, lipids, polysaccharides, pH, and ionic strength) on antimicrobial efficacy. Evidence from real food systems indicates that nanoemulsions often outperform free essential oils, although the magnitude of the effect strongly depends on matrix complexity and processing or storage conditions. The review further discusses critical aspects related to toxicity, safety, bioaccessibility, sensory acceptance, and regulatory considerations, as well as emerging evidence on adaptive responses and antimicrobial resistance risks associated with sublethal exposure to essential oil nanoemulsions. It is concluded that, despite their considerable technological potential, the industrial application of essential oil nanoemulsions requires further systematic studies in real foods, standardized protocols, and integrated risk assessments to ensure efficacy and safety under practical conditions.

Micro doi: 10.3390/micro6020032

Authors: Reiko Kohsaka Saho Komatsu Akiko Haruyama Toshiaki Ara Akihiro Kuroiwa Nobuo Yoshinari Atsushi Kameyama

The effects of different surface pretreatments on the microtensile bond strength (µTBS) between a bulk-fill resin-based composite cavity base material (Bulk Base HARD II) and 4-META/MMA-TBB resin (Super-Bond EX), which is often used as a luting agent for indirect dental restorations, were investigated. Six experimental treatments were established: 10% citric acid/3% ferric chloride conditioner (10-3), self-etching primer (Teeth Primer; TP), silane coupling agent (M&C Primer; MC), 10-3+MC, TP+MC, and a control group with no treatment. The µTBS was measured after 1 week (immediate group) and 6 months (aged group) of water storage. There were no significant differences in µTBS among the immediate subgroups. However, the aged 10-3+MC group exhibited the highest bond strength, significantly outperforming the control group. On the other hand, the µTBS of the aged TP group was significantly lower than those of both aged 10-3 and 10-3+MC. MC alone did not enhance bond strength, and its application after TP led to a nonuniform surface morphology, raising concerns about adhesive stability. Failure mode analysis indicated that cohesive failure within the luting cement was predominant, with mixed failures being more frequent in the aged TP group. Overall, MC may not be necessary, and 10-3 conditioning does not adversely affect bond strength. Based on the results of this in vitro study, the most effective clinical practice entails pretreatment of the prepared cavity employing a citric acid/ferric chloride conditioner.

Micro doi: 10.3390/micro6020031

Authors: Joseph B. Bernstein Tsuriel Avraham Bin Wang

Bias temperature instability (BTI) degradation is commonly described using empirical power-law kinetics; however, extraction of the time exponent and projection of lifetime remain highly sensitive to baseline definition and data representation. In conventional approaches, the threshold voltage shift is referenced to an initial value that cannot be measured simultaneously with stress, introducing uncertainty that can produce apparent curvature and variability in the extracted exponent. In this work, a baseline-independent linearization method is applied to representative published datasets spanning advanced silicon, SiC MOSFETs, and GaN power devices. By analyzing the measured degradation trajectories directly in a transformed time coordinate, the method removes curvature associated with baseline ambiguity and enables consistent extraction of the effective power-law exponent. Across all material systems examined, the extracted exponent exhibits systematic dependence on applied stress once baseline effects are reduced. This behavior challenges the commonly assumed constant-exponent formulation used in conventional lifetime projections and shows that even modest variations in the exponent can produce large differences in projected time-to-failure. A transformed lifetime representation based on TTFn is introduced, in which the influence of exponent variation is separated from the intrinsic voltage and temperature acceleration of the degradation rate. In this representation, the extracted acceleration parameters become more stable and physically interpretable. This formulation is consistent with standard reliability frameworks, including JEDEC JEP122G, in which the time exponent enters directly into the lifetime expression. These results demonstrate that baseline-independent analysis provides a unified framework for interpreting BTI degradation across disparate semiconductor technologies and suggest that explicit treatment of stress-dependent exponents is required for physically consistent lifetime modeling.

Micro doi: 10.3390/micro6020030

Authors: Martina Schwager Niklas Käfer Jenni Richter Hannes Reggel

The hydrogen evolution reaction (HER) plays a central role in electrochemical hydrogen production and requires catalysts that combine high activity with reduced noble metal usage. In this work, palladium nanoparticles (PdNPs) were deposited onto silver nanowire-modified graphite electrodes (Pd/AgNW/C) to investigate the influence of Pd loading on HER kinetics and catalytic efficiency. The electrodes were prepared by constant-current electrodeposition and characterized using polarization measurements and electrochemical impedance spectroscopy (EIS). The direct current (DC) results showed a pronounced enhancement of HER activity in the presence of Pd, while the highest mass-specific activity was observed at low Pd loadings. Increasing the Pd content further increased the overall current but reduced the catalytic efficiency when normalized to the Pd mass. EIS measurements revealed two contributions to the impedance response associated with processes occurring on different timescales. With increasing cathodic overpotential, both the charge transfer resistance and the low-frequency resistance decreased markedly, indicating accelerated reaction kinetics. The combined DC and alternating current (AC) analyses suggest that the silver nanowire network facilitates efficient electron transport and promotes a favorable dispersion of Pd nanoparticles at low loadings, enabling efficient HER catalysis with reduced noble metal usage.

Micro doi: 10.3390/micro6020029

Authors: Rifat Hussain Chowdhury Shunya Okamoto Takayuki Shibata Tuhin Subhra Santra Moeto Nagai

Resin 3D-printed molds are being increasingly favored for PDMS microfluidics across many disciplines. However, resin diversity, as well as secret manufacturer formulations, leads to a lack of standardization when using 3D printing for microscale applications. The impact of physical resin properties, both in its monomeric concoction and polymerized lattices at 100 µm or lower scales, needs quantification. We tested the performance of locally available resin formulations, isolating the impact of resin pigments and how it impacted the resin’s properties and performance. Lower resin viscosity improved feature fidelity (edge filleting < 25 µm) and improved resolution limit for recessed features, while cured polymer mechanical strength impacted the limit for positive mold features. We combined our findings to fabricate quality negative and positive mold structures in the mold and determined the best protocols associated with limitations during the fabrication of such structures. The methodologies in this study are expected to be widely applicable across various resin types and simplify the adoption of 3D printing protocols for specific feature fabrication in microscale molds for PDMS devices.

Micro doi: 10.3390/micro6020028

Authors: Mareni Arishima Shigehisa Aoki Sayaka Masaike Takayuki Narita

Vascularization remains a central challenge in thick tissue engineering. Building on our prior demonstration that carbonate buffer concentration governs multi-channel collagen gel (MCCG) architecture and perfusion culture performance, this study aimed to establish non-contact, orthogonal control of pore size and density in riboflavin-sensitized Type I collagen hydrogels via UV irradiation intensity and preparation temperature. UV intensity was modulated by varying the source-to-sample distance (25–52 mm); preparation temperature was set at 5, 25, or 40 °C; gelation kinetics were quantified using a vial-tilt assay. Pore area fraction ranged from 0.9% to 8.6% and Young’s modulus from 16 to 49 kPa depending on UV dose. Higher preparation temperatures accelerated gelation and produced smaller, more densely distributed pores, consistent with kinetically arrested phase separation. NIH/3T3 fibroblasts cultured on intermediate- and low-intensity UV scaffolds achieved >80% confluency by Day 7, with three-dimensional tissue-like organization and directionally aligned cellular bundles within large pores; cell metabolic activity, assessed by CCK-8 assay, remained consistently high throughout the culture period. These results demonstrate that UV irradiation intensity and preparation temperature are independently tunable, non-contact parameters for reproducible fabrication of collagen scaffolds with tunable vascular-like pore networks, complementing and extending the chemical (buffer concentration) design space of MCCG-based perfusion culture systems.

Micro doi: 10.3390/micro6020027

Authors: Sahin Demirci Jorge H. Torres Seneshaw Tsegaye Nurettin Sahiner

The widespread use of herbicides such as paraquat and glyphosate is a serious environmental and health concern due to their persistence, mobility, and toxicity in aquatic ecosystems. Composites of alginic acid (Alg) are prepared with carbonaceous materials such as graphene oxide (GO), carbon particles (CPs), porous carbon particles (PCPs), carbon black (CB), and carbon nanotubes (CNTs) were synthesized and evaluated as sorbents for the removal of cationic herbicide paraquat and the anionic herbicide glyphosate. The resulting Alg-based beads are environmentally safe because of the materials used during their preparation, such as a biopolymer, Alg, carbonaceous substances (GO, CPs, PCPs, and CB) as composite moieties, and Ca(II) ions as cross-linkers. The Alg–bead composite possessed strong swelling ability ranging from 1700% to 2500%, which led to swollen beads of spherical shape and an average diameter of 3 mm, each containing 20% of carbonaceous materials. Amongst all Alg-based beads prepared for paraquat and glyphosate removal from the aquatic environment, the highest adsorption capacity was attained for Alg–porous carbon particle (Alg-PCP) composites. The Alg-PCP beads were capable of adsorbing 85.7 ± 2.9 mg/g and 31.6 ± 2.2 mg/g from 50 mL of 250 ppm solutions of paraquat and glyphosate, respectively. In contrast, bare Alg beads adsorbed only 39.7 ± 1.8 mg/g and 12.9 ± 1.7 mg/g, respectively. A 250 mg Alg-PCP bead composite achieved a 91% removal of paraquat from a 50 mL solution containing 250 ppm of paraquat. These results show that Alg–PCP can be used to mitigate herbicide contamination in water, protecting aquatic ecosystems and addressing associated environmental and health risks.

Micro doi: 10.3390/micro6020026

Authors: Yudai Oda Masaki Miyamoto Shogo Miyata

Mechanical confinement plays an important role in regulating tumor growth and invasion; however, the quantitative, time-resolved, three-dimensional evaluation of confined tumor spheroids remains technically challenging. In this study, we developed a custom-built selective plane illumination microscopy (SPIM)-based monitoring platform for long-term volumetric imaging of tumor spheroids under mechanically confined conditions. This system integrates a culture housing unit and a transparent cuvette-based spheroid culture method optimized for SPIM observation. Colorectal adenocarcinoma-derived cell spheroids were embedded in agarose gels with defined concentrations to modulate the stiffness of the surrounding matrix. Bright-field imaging and viability analyses confirmed sustained spheroid growth without necrotic core formation over a 4-day culture period, demonstrating that the SPIM-based system maintained the physiological culture conditions. Three-dimensional imaging using SPIM enabled a quantitative evaluation of spheroid growth and anisotropic invasion. Volumetric expansion was observed under all confinement conditions. Notably, increasing the matrix stiffness enhanced both the volumetric growth rate and anisotropic invasion, indicating stiffness-dependent directional growth under mechanical confinement. The developed SPIM-based platform has the potential to serve as a practical tool for the time-resolved three-dimensional analysis of tumor spheroid growth and may provide a useful approach for investigating the mechanobiological regulation of tumor progression in confined microenvironments.

Micro doi: 10.3390/micro6020025

Authors: Sonia J. Bailón-Ruiz Yarilyn Cedeño-Mattei Nayeli Colón-Dávila Luis Alamo-Nole

The environmental persistence of β-lactam antibiotics represents a growing ecological concern, requiring materials capable of combined adsorption and catalytic degradation. Herein, pure ZnS and 1% Fe-doped ZnS nanoparticles were synthesized via microwave-assisted treatment and evaluated for the removal of ceftaroline fosamil from aqueous media. Transmission electron microscopy revealed quasi-spherical nanoparticles below 10 nm, while selected area electron diffraction confirmed a face-centered cubic structure retained after Fe incorporation. UV-Vis spectroscopy showed similar absorption edges (~316 nm), indicating negligible band-gap variation, whereas photoluminescence analysis demonstrated strong emission quenching in Fe-ZnS, indicating suppressed electron–hole recombination. Point-of-zero charge measurements (pHPZC ≈ 4.6 for ZnS; 4.5 for Fe-ZnS) indicated negatively charged surfaces under circumneutral conditions, influencing interfacial interactions with the antibiotic. Adsorption experiments followed the Langmuir isotherm model, with Fe-ZnS exhibiting a higher maximum adsorption capacity (156 mg g−1) compared to ZnS (115 mg g−1). Under UV irradiation (302 nm), Fe-ZnS achieved near-complete degradation at a catalyst loading of 500 ppm. Liquid chromatography–mass spectrometry analysis revealed the transformation of ceftaroline fosamil (m/z 685.01) into ceftaroline (m/z 605.05) via phosphate group loss, followed by the formation of intermediate fragments at m/z 492.08 and 308.03, associated with cleavage of the thiadiazol-amine moiety and subsequent opening of the cephalosporin ring. After extended irradiation, these intermediates diminished, and a fragment at m/z 356.01 was detected, suggesting further breakdown through thioether bond cleavage. These results support a degradation pathway involving sequential dephosphorylation and fragmentation of the cephalosporin core. Overall, the enhanced performance of Fe-ZnS arises from the synergistic interplay between surface charge characteristics and dopant-modulated charge carrier dynamics, highlighting its potential for antibiotic remediation in aquatic environments.

Micro doi: 10.3390/micro6020024

Authors: Sashka Alexandrova Anna Szekeres Evgenia Valcheva Mihai Anastasescu Hermine Stroescu Madalina Nicolescu Mariuca Gartner

Nitridation of different materials using ion implantation is of considerable interest for many applications. As electronic components, oxynitride (SiOxNy) layers exhibit beneficial properties such as precise compositional variability, refractive index tunability, oxidation resistance, and low mechanical stress. In the present study we investigate nanoscale SiOxNy synthesized using ion implantation methods. To introduce N+ ions into a shallow Si subsurface region, both conventional ion beam implantation and plasma immersion ion implantation with subsequent high-temperature treatment in dry O2 are used. The optical and morphological properties and chemical bonding of formed SiOxNy layers were studied by applying spectroscopic ellipsometry in the range of VIS-Near IR (SE) and IR (IR-SE), Raman spectroscopy and Atomic Force Microscopy (AFM). Monte Carlo modeling of implant profiles contributed to understanding physical and chemical processes and predicted different influences of the incorporated N+ ions on the oxidation mechanism, confirmed by the thickness dependence of SiOxNy/Si layers obtained from the SE data analysis. IR-SE spectral analysis established the formation of Si-O, Si-N, Si-N-O and Si-Si chemical bonds in the grown layers. The occurrence of amorphization of the Si crystal lattice due to incorporation of high-energy N+ ions into the Si lattice is confirmed by the Raman and ellipsometry results. The free Si atoms can congregate, forming nanocrystalline clusters. AFM imaging revealed that both implantation methods left the surface of the resulting SiOxNy layers considerably smooth with similar roughness parameter values. The results of the studies imply that the technological approaches used allow the production of high-quality nanoscale silicon oxynitride films with appropriate tunable composition and properties for possible application in advanced electronic devices for nanoelectronics, optoelectronics and sensor applications.

Micro doi: 10.3390/micro6020023

Authors: Victor Petrov Timofey Grishin Alexandra Starnikova

This study investigates the properties of ZnO nanorod-based sensors and ZnO nanorods modified with tin dioxide (ZnO/SnO2) and gold (ZnO/Au) nanoclusters and their response to low concentrations of carbon monoxide (CO). It was demonstrated that the ZnO/SnO2(3) nanorod-based sensor exhibited the highest sensitivity (S = 1.64) to 10 ppm CO, while the ZnO/Au(3) sensor displayed the shortest response (69–207 s) and recovery (203–233 s) times. This behavior can be explained by ZnO/Au and ZnO/SnO2 nanostructures having low activation energies (0.23–0.25 eV) and high potential barrier values (0.37–0.43 eV). Sensors based on ZnO/Au and ZnO/SnO2 nanorods demonstrate sensitivity to 10 ppm CO at 250 °C and at 200 °C. In contrast, ZnO nanorod-based sensors are sensitive to 2 ppm CO at 250 °C.

Micro doi: 10.3390/micro6010022

Authors: Jude N. Ike Raymond Tichaona Taziwa

Over the past two decades, organic semiconductors have attracted significant research interest due to their advantageous features, including low-cost fabrication, lightweight properties, and portability, for photonic device applications. In this study, nickel sulfide doped with cobalt (NiS/Co) nanocomposites were successfully synthesized via a wet-chemical processing technique and used as a dopant in the active layer of thin-film organic solar cells (TFOSCs). The poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) blend was used as the active layer in this investigation. The devices were fabricated with NiS/Co nanocomposites at 1 wt%, 2 wt%, and 3 wt% in the active layer to determine the optimal dopant concentration. However, the experimental evidence clearly showed that the solar cell’s performance depends on the concentration of the NiS/Co nanocomposites. As a result, the highest power conversion efficiency (PCE) recorded in this experimental work was 6.11% at a 1% doping concentration, compared with 2.48% for the pristine reference device under AM 1.5G illumination (100 mW/cm2) in ambient conditions. The optical and electrical properties of the active layers are found to be strongly influenced by the inclusion of NiS/Co nanocomposites in the medium. However, the device doped with 1 wt% NiS/Co nanocomposite exhibits the highest absorption intensity, consistent with the better performance observed in this study, which can be attributed to the localized surface plasmon resonance (LSPR) effect. The optical and morphological characteristics of the synthesized NiS/Co nanocomposites were comprehensively analyzed using high-resolution transmission electron microscopy (HRTEM), high-resolution scanning electron microscopy (HRSEM), and additional complementary techniques.

Micro doi: 10.3390/micro6010021

Authors: Warlen Monfardini João Victor Vieira João Batista Fogagnolo Juliano Soyama

Laser processing has been widely investigated as an effective approach for improving surface properties and consolidating advanced materials, particularly complex alloys such as titanium aluminides (TiAl). In this study, laser surface remelting was applied to binary (Ti-45Al) and ternary (Ti-45Al-2Co and Ti-45Al-2Ni) alloys produced by powder metallurgy via blended elemental (BE) and pre-alloyed (PA) powder routes. Laser powers of 50 and 100 W were employed, resulting in a high-energy-density surface remelting regime applied to both green compacts and sintered samples with relatively high initial porosity, under an argon-controlled atmosphere. Microstructural and phase analyses were performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD), while mechanical behavior was assessed by instrumented microindentation. Laser processing promoted the formation of a dense and homogeneous surface layer, approximately 150 μm thick, accompanied by significant microstructural refinement and enhanced hardness and elastic modulus. While rapid solidification led to crack formation in laser-treated sintered samples, the green compacts exhibited defect-free modified layers. Overall, the results demonstrate that laser surface remelting is an effective strategy for enhancing the surface integrity and mechanical performance of TiAl alloys processed by powder metallurgy.

Micro doi: 10.3390/micro6010020

Authors: Iosif Galanakis

Employing ab initio electronic structure methods, in this study, I examine the effect of order on the spin gapless semiconducting behavior of the Mn2CoAl Heusler compound. The occurrence of atomic disorder in general destroys the spin gapless semiconductivity observed in the inverse XA lattice structure; however, in some cases, novel magnetic configurations emerge. In the case of structures derived from the XA structure, where only Mn-Co or Mn-Al atoms are mixed, Mn2CoAl alloy presents a half-metallic magnetic character. In the case of full disorder (A2 lattice structure), where atoms occupy all sites with the same probability, the ground state is an antiferromagnetic metallic one. The L21 and B2 lattice structures, where Mn atoms occupy both sites of a similar local environment, correspond to a ferromagnetic state of very high spin magnetic moment per formula unit. The present study encompasses a much larger variety of disordered structures in comparison with other studies in the literature. It concludes that the control and minimization of the concentration of impurities at anti-sites is imperative to achieving optimal performance in spintronic devices based on spin gapless semiconducting Mn2CoAl.

Micro doi: 10.3390/micro6010019

Authors: Evangelia Dimeli Dimitrios I. Anyfantis Athanasios Sigalos Alexandros Banis Dimitrios Niarchos

This work investigates the fabrication and performance of axially compressed isotropic epoxy-bonded NdFeB-type magnets produced from melt-spun powders with partial substitution of (Nd,Pr) by (La,Ce). Four alloy compositions were synthesized and processed into bonded magnets using two powder-to-binder weight ratios (95:5 and 96.5:3.5). Structural analysis confirms that all substituted alloys retain the tetragonal Nd2Fe14B phase (up to ~95 wt%) even at high substitution levels, while the lattice parameters decrease slightly with increasing (La,Ce) content. Microscopy analysis confirms a homogeneous distribution of the binder phase around the powder particles, demonstrating uniform binder–powder integration. Thermal analysis reveals composition-dependent Curie temperatures and enhanced crystallization onset in highly substituted powders. Magnetic measurements on both powders and bonded magnets show that increasing substitution leads to a gradual reduction in remanence, coercivity, and energy product, though all samples maintain strong hard-magnetic behavior. Increasing the powder fraction to 96.5 wt.% significantly improves all magnetic parameters due to higher magnetic-phase density and enhanced interparticle coupling, yielding bonded magnets with densities up to ~80% of the theoretical value. The resulting magnets achieve competitive performance, uniform field distribution and isotropic magnetization with (BH)max values about 65 kJ/m3, a coercivity around 660 kA/m, and superior thermal stability compared with commercial bonded NdFeB magnets. Overall, partial substitution with light rare-earth elements (La,Ce) provides a cost-effective route to high-density bonded NdFeB magnets that combine strong magnetic performance, enhanced thermal stability, and suitability for lightweight, complex-shaped industrial applications. Surprisingly, the coefficients of the temperature variation of coercivity and (BH)max are much better compared to the commercial NdFeB bonded magnets.

Micro doi: 10.3390/micro6010018

Authors: Julia Rieber Tiziano A. Schweizer Gabor Kadler Gabriella Meier Bürgisser Pietro Giovanoli Johanna Buschmann

Background: Surgical tendon rupture repair suffers from scar formation, leading to tendons with inferior mechanics and consequently to re-ruptures, as well as from adhesion formation to the surrounding tissue, reducing the range of motion. In an approach of re-purposing the phytochemical Bakuchiol to be incorporated in the polymer DegraPol® (DP), we fabricated a novel implant material by emulsion electrospinning. Methods: To characterize the emulsion electrospun novel materials, we used Scanning Electron Microscopy (SEM) to determine the fiber diameter and pore size. In addition, we used Fourier Transformed Infrared Spectroscopy (FTIR). Finally, we planted the materials onto the chorioallantoic membrane of the chicken embryo (CAM assay) to assess tissue integration and collagen expression. Results: While the pure DP meshes were very well integrated in the CAM assay and showed a significantly higher collagen deposition within the scaffold, the DP + Bakuchiol meshes exhibited poor tissue integration, showing rather the beginning of a fibrous encapsulation. Conclusions: The novel electrospun material DP + Bakuchiol could be used as an anti-adhesion barrier to prevent tendon adhesion.

Micro doi: 10.3390/micro6010017

Authors: Xuening Zhao Kangyu Liu Jiaying Yuan Yuming Li

One-dimensional alumina nanorods have garnered significant attention due to their unique physical and chemical properties, which hold great promise for applications in catalysis, sensing, and other fields. However, the precise control over the morphology and properties of these nanorods remains a challenge, particularly in achieving a high specific surface area and desirable crystallinity. In this work, we explored the hydrothermal synthesis of alumina nanorods, focusing on the effects of structure-directing agents. It was observed that extending the hydrothermal time and optimizing the temperature led to the formation of nanorods with enhanced crystallinity and specific surface area. The addition of urea and different structure-directing agents significantly influenced the morphology and properties of the nanorods. Furthermore, density functional theory (DFT) calculations revealed the underlying mechanisms of how these structure-directing agents affect the adsorption and growth of alumina nanorods on different crystal planes. Our findings suggest that by carefully tuning these parameters, it is possible to achieve alumina nanorods with optimized properties. This work not only provides a systematic approach to the synthesis of alumina nanorods but also opens up new possibilities for the development of advanced materials with tailored properties for a wide range of applications.

Micro doi: 10.3390/micro6010016

Authors: Arjun Thakur Shreeji Pandit Abhishek Singh Ashish Mathur Krishna Kant

Microfluidics provides precise control of microscale fluid transport and has become central to biomedical, pharmaceutical, and industrial technologies. However, conventional fabrication methods such as photolithography and soft lithography require cleanroom facilities, use costly materials, and offer limited capability for constructing complex or multi-material architectures. This review highlights emerging manufacturing strategies, focusing on polymer-based micro-milling as an accessible and cost-effective alternative for microfluidic device production. Advances in micro-milling now enable the fabrication of microchannels and functional features with improved dimensional accuracy and surface quality, while additive manufacturing offers complementary rapid prototyping and design flexibility. Micro-milling is particularly promising for rapid prototyping of polymeric biosensor chips designed for point-of-care diagnostics. The technique supports diverse materials and eliminates reliance on cleanroom processing. Critical parameters, including tool geometry, spindle speed, and feeding rate, strongly influence fidelity and surface roughness, which directly affect biosensor sensitivity. Despite its advantages, challenges such as tool wear, burr formation, and limits on minimum feature size continue to hinder reproducibility. Recent progress in toolpath optimization, hybrid additive–subtractive methods, and real-time process monitoring shows the potential to overcome these barriers. Overall, micro-milling offers a scalable and economical route for fabricating accessible microfluidic and biosensing platforms, with future work needed to standardize processes and improve integration with surface functionalization methods.

Micro doi: 10.3390/micro6010015

Authors: Christian Ebere Enyoh Qingyue Wang

The rapid and selective discrimination of microplastics (MPs) is a critical analytical challenge, particularly as current carbon quantum dot (CQD)-based sensors often rely on single-wavelength “turn-on/off” or staining mechanisms that lack polymer-specific resolution. This work addresses these limitations by presenting a mechanism-driven fluorescence sensing platform using ultra-fine polyamide-derived carbon quantum dots (PACQDs; ~1.4 nm) to identify three prevalent MPs: polyamide (PA), polypropylene (PP), and polyethylene terephthalate (PET). Excitation–emission matrix (EEM) spectroscopy reveals polymer-specific photophysical responses: PAMPs and PPMPs induce fluorescence enhancement of 11.66% and 11.43%, respectively, whereas PETMPs cause net quenching (−4.61%) alongside a distinct, red-shifted emission band. Despite a common scatter-dominated peak at 290/308 nm, quantitative discrimination is achieved via integrated intensity and red/blue emission ratios (0.0137 for PAMPs, 0.0098 for PPMPs, and 0.0072 for PETMPs). Multivariate analysis reinforces this discrimination. Parallel factor analysis (PARAFAC) resolves the EEM data into three fluorescent components representing the intrinsic CQDs core and two interaction-induced surface states with a rank 3 model reducing the relative reconstruction error from 0.1625 to 0.1285. Principal component analysis (PCA) yields clear separation of the polymer classes, with the first two principal components capturing ~88% of the total spectral variance. ATR–FTIR spectroscopy provides direct molecular evidence for the underlying mechanisms: amide–amide coupling and interfacial rigidification for PAMPs; hydrophobic interaction without spectral shifts for PPMPs; and a synergistic interaction involving hydrogen bonding and π–π stacking for PETMPs. In particular, these polymer-specific fluorescence fingerprints are largely preserved in tap water, despite elevated background intensity and partial contrast attenuation, demonstrating the resilience of the EEM–chemometric approach under realistic matrix conditions. Collectively, the strong agreement between fluorescence metrics, multivariate signatures, and interfacial chemistry establishes a robust structure–property framework and positions PACQDs as a rapid, label-free, and matrix-tolerant platform for reliable microplastic discrimination in environmental analysis.

Micro doi: 10.3390/micro6010014

Authors: László Égerházi Erika Griechisch Tamás Szörényi

Wire explosion (WE) inherently generates particle ensembles spanning the nano- to microscale, posing challenges for conventional characterization methods in terms of capturing the full particle population. To address this issue, spectrophotometric analysis combined with algorithmic spectrum reconstruction based on Mie theory and constrained distribution models were employed to characterize copper WE products formed in aqueous surroundings within the 4–12 kV discharge voltage range. Three independent fitting strategies, specifically a semimanual fitting, an evolutionary algorithm, and a grid search, were applied to retrieve the size distributions and relative shares of copper and copper oxide particles as a function of discharge voltage. Based on experimental and theoretical findings, lognormal and normal distributions across the 10–300 nm diameter range were assumed as constraints for oxide and metallic fractions, respectively. The reconstructed metallic copper population exhibited mean diameters ranging from 123 to 181 nm, while oxidized fractions followed lognormal distributions centred near 10 nm mode diameters. Voltage-dependent trends revealed an optimal discharge regime between 6 kV and 8 kV, where the exploded fraction reached approximately 63% and the metallic mass share exceeded 80%. These results confirmed that spectrophotometry represents an essential tool for the quantitative characterization of such complex, wide-range systems.

Micro doi: 10.3390/micro6010013

Authors: Navaratnarajah Kuganathan Tharmarajah Manoranjan

The functionalization of molecules on C60 is a promising engineering approach, as non-covalently governed fullerene surfaces facilitate reversible host–guest recognition, tunable electronic communication, and conformationally adaptive molecular adsorption. In this work, spin-resolved simulations using density functional theory (DFT) were conducted to examine the interaction between a newly identified arylalkanone isolated from the medicinal species Myristica ceylanica and the nanocarbon framework of C60 fullerene, including doped configurations incorporating group III elements (B, Al, Ga, In and Tl). The results indicate that the arylalkanone binds to pristine C60 through an exothermic, energetically favourable binding process, supporting thermodynamically viable molecular uptake. Among the doped models, B substitution exhibits the greatest overall thermodynamic preference; however, Al doping produces the most pronounced enhancement in binding energy, identifying the Al-doped configuration as the most effective surface-uptake architecture in relative terms. Across all complexes, a small amount of charge transfer is noted, signifying weak yet persistent electronic coupling between the ligand and the carbon carrier. Additionally, all doped fullerenes demonstrate induced magnetic behaviour, a property of increasing relevance in spintronics research, suggesting that these complexes may hold future value in spin-dependent electronic and molecular-recognition-guided nanoscale biomedical engineering.

Micro doi: 10.3390/micro6010012

Authors: Heyi Wei Yang Zou Xuecheng Qu Xi Cui Zhou Li

Nanomaterials have emerged as a pivotal driving force in the field of biomedicine due to their unique physicochemical properties. This article systematically reviews the design, synthesis, and characterization of novel nanomaterials, with a focus on their application advances in three key areas: targeted drug delivery, tissue engineering and regenerative medicine, and disease diagnosis and sensing. In drug delivery, nanocarriers enable precise drug targeting and controlled release through surface functionalization and stimuli-responsive design. In tissue engineering, nanocomposite scaffolds mimic the structure and function of the natural extracellular matrix, providing an ideal microenvironment for tissue repair. In disease diagnosis, nanomaterials significantly enhance the sensitivity and specificity of biosensors, promoting the development of real-time, non-invasive, and ultra-early detection technologies. The article further summarizes current challenges in the clinical translation of nanomedicine and envisions its future trends toward intelligence, personalization, and the integration of diagnosis and therapy.

Micro doi: 10.3390/micro6010011

Authors: Ewelina Musielak Agnieszka Feliczak-Guzik Aleksandra Majchrzak-Celińska Anna Rybarczyk Violetta Krajka-Kuźniak

Malignant gliomas, including glioblastoma multiforme (GBM) and grade 4 astrocytoma, are the most common types of brain tumors in adults. Standard treatment for gliomas includes adjuvant chemotherapy, typically based on temozolomide, combined with radiotherapy. However, its effectiveness is severely hindered by the limited ability of drugs to cross the blood–brain barrier and by the hyperactivation of the canonical Wnt signaling pathway, which drives tumor cell survival. Therefore, innovative drug combinations and novel delivery strategies are crucial for overcoming these barriers. Polymeric micelles represent a promising approach for enhancing drug delivery to brain tumors. This study aimed to obtain micelles containing cannabidiol (CBD), celecoxib (CELE), and temozolomide (TMZ), as well as their combinations, and to verify their anti-glioma properties. The study involved optimizing the micelle composition, incorporating active ingredients, and assessing the temporal stability of the resulting nanocarriers under varying temperature conditions. The GBM cell line U-138 MG and astrocytoma cell line U-87 MG were used to evaluate the biologic effects of the tested micelles. Cytotoxicity was assessed using the MTT assay, and flow cytometry was used to analyze the effect of the micelles on apoptosis. Western blot analysis was employed to assess the impact of the tested nanoformulations on the Wnt/β-catenin signaling pathway. The optimized micelles demonstrated strong cytotoxic and proapoptotic effects, accompanied by attenuation of the Wnt/β-catenin pathway. These preliminary findings support the therapeutic potential of polymeric micelles for treating malignant gliomas; however, further in vitro and in vivo studies are required to confirm their clinical applicability.

Micro doi: 10.3390/micro6010010

Authors: Luis Alamo-Nole Glorimar Rivera-Rodriguez

The production of quantum dots (QDs) has increased due to their wide variety of commercial products and applications. QDs can be dangerous in the environment because their small size can encourage their incorporation into living systems. In this project, ZnS and ZnSSe were synthesized under microwave irradiation, generating a water-stable nanomaterial. The bandgap energies calculated using the UV-Vis spectra were 3.81 and 3.86 eV for ZnS and ZnSSe QDs, respectively, indicating that the selenium worked as a dopant agent. The photoluminescence analysis shows narrow emission peaks, confirming a low size distribution, and the selenium doping generated a blue shift. The crystal size of both nanomaterials was around 7 nm. The cellular toxicity of these nanomaterials was evaluated using Chinese Hamster Ovary (CHO) Cells (a standard mammalian cell model). The results suggest that ZnS and ZnSSe QDs slightly affect the viability of CHO Cells, but Zn2+ decreases the viability at concentrations higher than 20 mg/L. The content of zinc inside cells (by ICP-OES) suggested that QDs can enter cells more easily than Zn2+. Therefore, the decrease in cell viability caused by Zn2+ outside the cells is likely due to its effect on cell membrane integrity, suggesting that these nanomaterials are less toxic than bulk materials.

Micro doi: 10.3390/micro6010009

Authors: Abbass Akhdar Amine Geneste Asfaw Zegeye Bénédicte Prélot Jerzy Zajac

Fe-oxyhydroxides can incorporate toxic metals during the formation of mineral phases in soils and sediments, thereby potentially altering the environmental reactivity of metals and impacting the microbial communities. In this study, isothermal microcalorimetry has been used to monitor the metabolic activity of Pseudomonas putida KT2440 exposed to pure ferrihydrite and to Pb-, Cd-, and As-bearing ferrihydrites under oxygen-limited conditions. Calorimetric measurements of the integral heat released during the exponential growth were combined with the analysis of dissolved iron and heavy metals, as well as the glucose uptake, to understand how heavy metal incorporation modifies mineral reactivity and microbial heat output. Pure ferrihydrite decreased the integral heat by about 45%, primarily due to glucose and phosphate depletion, Fe(III) leaching, and mineral–cell aggregation. Heavy metal dopants were found to modulate nutrient availability, surface charge, and Fe solubilization, which, in turn, influenced the integral heat. Pb-Fh generated the highest ferrihydrite dissolution and metabolic heat, with a maximum effect at intermediate substitution levels. As-Fh induced moderate Fe release and metabolic activity, consistent with the enhanced phosphate sorption and lowered surface charge. Cd-bearing Fh showed minimal reactivity and yielded the lowest heat output. Microcalorimetry was proven useful for unraveling microbe–mineral interactions in complex contaminated environments.

Micro doi: 10.3390/micro6010008

Authors: Kuikui Zhang Lezhou Fang Can Xu Weiwei Zhou Xiaoqiu Deng Chenkun Shan Quanling Zhang Lijia Pan

Regenerative medicine is increasingly leveraging the synergies between bioinspired conductive biomaterials and 3D/4D bioprinting to replicate the native electroactive and hierarchical microenvironments essential for functional tissue restoration. However, a critical gap remains in the intelligent integration of these technologies to achieve dynamic, responsive tissue regeneration. This review introduces a “bioinspired material–printing–function” triad framework to systematically synthesize recent advances in: (1) tunable conductive materials (polymers, carbon-based systems, metals, MXenes) designed to mimic the electrophysiological properties of native tissues; (2) advanced 3D/4D printing technologies (vat photopolymerization, extrusion, inkjet, and emerging modalities) enabling the fabrication of biomimetic architectures; and (3) functional applications in neural, cardiac, and musculoskeletal tissue engineering. We highlight how bioinspired conductive scaffolds enhance electrophysiological behaviors—emulating natural processes such as promoting axon regeneration cardiomyocyte synchronization, and osteogenic mineralization. Crucially, we identify multi-material 4D bioprinting as a transformative bioinspired approach to overcome conductivity–degradation trade-offs and enable shape-adaptive, smart scaffolds that dynamically respond to physiological cues, mirroring the adaptive nature of living tissues. This work provides the first roadmap toward intelligent electroactive regeneration, shifting the paradigm from static implants to dynamic, biomimetic bioelectronic microenvironments. Future translation will require leveraging AI-driven bioinspired design and organ-on-a-chip validation to address challenges in vascularization, biosafety, and clinical scalability.

Micro doi: 10.3390/micro6010007

Authors: Ryosuke Nakamura Rie Togawa Daisuke Koizumi Masataka Kawarasaki Keishi Iohara Michiyo Honda

Dental caries is a major global health issue associated with biofilm formation by Streptococcus mutans (S. mutans). Conventional antimicrobials often fail to eliminate biofilms due to their structural resistance, highlighting the need for new strategies. This study investigated the antibacterial and antibiofilm effects of protamine peptides (PPs), which are cell-penetrating antimicrobial peptides derived from salmon protamine, alone and in combination with antimicrobial agents. Antimicrobial susceptibility was evaluated using alamarBlue® and colony count assays, while biofilm formation was analyzed using crystal violet staining, confocal microscopy, and extracellular polysaccharide (EPS) quantification. PP exhibited moderate antibacterial activity but strongly suppressed EPS accumulation and biofilm development, leading to a flattened biofilm structure. Cotreatment with ε-poly-L-lysine (PL) significantly enhanced antibacterial and antibiofilm effects compared with either agent alone, whereas this effect was not observed with other cationic polymers. Fluorescence imaging revealed that PL promoted the intracellular localization of PP without increasing membrane damage, indicating a cooperative mechanism by which PL enhances membrane permeability and PP targets intracellular sites. These findings demonstrate that combining a cell-penetrating peptide with a membrane-active agent is a novel approach to overcome bacterial tolerance. The PP–PL combination effectively suppressed S. mutans growth and biofilm formation through dual action on membranes and EPS metabolism, offering a promising basis for the development of peptide-based preventive agents and biofilm-resistant dental materials.

Micro doi: 10.3390/micro6010006

Authors: Nurettin Sahiner Sahin Demirci Betul Ari Selin S. Suner Mehtap Sahiner Olgun Guven

A facile and single-step synthesis of poly(L-Cysteine) (p(L-Cys)) particles through microemulsion polymerization using tetrakis(hydroxymethyl) phosphonium chloride (THPC) as crosslinker is accomplished for the first time. The L-Cys:THPC ratio in p(L-Cys) particles was calculated as 80:20% (by weight) with elemental analyses, and the generation of p(L-Cys) particles was confirmed. SEM imaging revealed a popcorn-like morphology of the p(L-Cys) particles with a 1–20 µm particle size range. The isoelectric point of p(L-Cys) particles was determined at pH 1.15 via zeta potential measurements. The hydrolytic degradation of p(L-Cys) particles was determined as about 85% within 3 h (by weight). The p(L-Cys) particles displayed excellent blood compatibility with a hemolysis % ratio of <2.3% and a blood clotting index of 95% at 1 mg/mL concentration. Moreover, cell compatibility tests up to 50 mg/mL against L929 fibroblast cells exhibited about 90% cell viability for p(L-Cys) particles versus 58% for L-Cys molecule. The antimicrobial efficacy of the L-Cys molecules was notably enhanced in p(L-Cys) particles, exhibiting a 5-fold reduction in minimal bactericidal concentration (MBC) values against E. coli (Gram-negative, ATCC 8739) and a 2-fold reduction against S. aureus (Gram-positive, ATCC 6538). Additionally, the antioxidant capacity of p(L-Cys) particles was retained somewhat, measured as 0.14 ± 0.01 µM versus 2.25 ± 0.03 µM Trolox equivalent/g for L-Cys. Therefore, p(L-Cys) particles are versatile and offer a unique avenue for immense biomedical use.

Micro doi: 10.3390/micro6010005

Authors: Azam Ali Muhammad Zaman Khan Sana Rasheed Rimsha Imtiaz

Integrating antibacterial fabrics into wearable technology represents a transformative advancement in healthcare, fashion, and personal hygiene. Antibacterial fabrics, designed to inhibit microbial growth, are gaining prominence due to their potential to reduce infections, enhance durability, and maintain cleanliness in wearable devices. These fabrics offer effective antimicrobial properties while retaining comfort and functionality by incorporating nanotechnology and advanced materials, such as silver nanoparticles, zinc oxide, titanium dioxide, and graphene. The production techniques for antibacterial textiles range from chemical and physical surface modifications to biological treatments, each tailored to achieve long-lasting antibacterial performance while preserving fabric comfort and breathability. Advanced methods such as nanoparticle embedding, sol–gel coating, electrospinning, and green synthesis approaches have shown significant promise in enhancing antibacterial efficacy and material compatibility. Wearable technology, including fitness trackers, smart clothing, and medical monitoring devices, relies on prolonged skin contact, making the prevention of bacterial colonization essential for user safety and product longevity. Antibacterial fabrics address these concerns by reducing odor, preventing skin irritation, and minimizing the risk of infection, especially in medical applications such as wound dressings and patient monitoring systems. Despite their potential, integrating antibacterial fabrics into wearable technology presents several challenges. This review provides a comprehensive overview of the key antibacterial agents, the production strategies used to fabricate antibacterial textiles, and their emerging applications in wearable technologies. It also highlights the need for interdisciplinary research to overcome current limitations and promote the development of sustainable, safe, and functional antibacterial fabrics for next-generation wearable.

Micro doi: 10.3390/micro6010004

Authors: Asma Gzaiel Khalil Aouadi Aurélien Besnard Yoann Pinot Corinne Nouveau Faker Bouchoucha Yahya Agzenai Ben Salem Amina Guessabi Boudjemaa Bouaouina

This paper investigates the properties of zirconium oxide thin films deposited on Ti6Al4V and Si substrates via oblique angle deposition, using varying out-of-plane θ (15 to 85°) and in-plane Φ (0 and 180°) substrate orientations. ZrO2 films have garnered significant interest due to their antibacterial properties and mechanical performance. The aim is to engineer surfaces capable of inhibiting bacterial growth while maintaining excellent mechanical integrity. The methodology combines experimental deposition by DC magnetron sputtering with multi-scale simulations using SRIM and SIMTRA. Structural analyses were conducted via X-ray diffraction, while microstructure and surface morphology were examined using scanning electron microscopy and atomic force microscopy. Nanoindentation tests were performed to assess hardness and elastic modulus. Results revealed that increasing the incidence angle α from 7 to 74° significantly affected surface morphology, microstructure, film thickness, and columnar tilt. The hardness and Young’s modulus of the films exceeded those of Ti6Al4V, for incidence angle α between 7 and 50°, but decreased with the increasing incidence angle α. Furthermore, the films exhibited strong antibacterial activity against Gram-positive pathogens (Staphylococcus aureus), particularly at the highest incidence angle α, with inhibition rates exceeding 90%.

Micro doi: 10.3390/micro6010003

Authors: Haider Jaafar Chilabi Luqman Chuah Abdullah Waleed Al-Ashtari Azizan As’arry Hanim Salleh Eris E. Supeni

The growing need for self-powered Internet of Things networks has raised interest in converting abundant waste into reliable energy harvesters despite long-standing material and technology challenges. As demand for environmentally friendly self-powered IoT devices continues to rise, attention toward green waste as an eco-friendly energy source has strengthened. However, its direct utilisation in high-performance energy harvesters remains a significant challenge. Driven by the growing need for renewable sources, the triboelectric nanogenerator has emerged as an innovative technology for converting mechanical energy into electricity. In this work, the design, fabrication, and characterisation of a rotating triboelectric energy harvester as a prototype device employing date seed waste as the tribopositive layer are presented. The date seeds particles, measuring 1.2 to 2 mm, were pulverised using a grinder, mixed with epoxy resin, and subsequently applied to the grating-disc structure. The coated surface was machined on a lathe to provide a smooth surface facing. The performance of the prototype was evaluated through a series of experiments to examine the effects of rotational speed, the number of grating-disc structures, the epoxy mixing process, and the prototype’s influence on the primary system, as well as to determine the optimal power output. An increase in rotational speed (RPM) enhanced power generation. Furthermore, increasing the number of gratings and pre-mixing of epoxy with the biomaterial resulted in enhanced output power. Additionally, with 10 gratings, operating at 1500 rpm, and a 24 h pre-mixing method, the harvester achieved maximum voltage and power outputs of 129 volts and 1183 μW at 7 MΩ.

Micro doi: 10.3390/micro6010002

Authors: Irene Méndez-Mesón Alba Sebastián-Martín Mónica Grande-Alonso Rafael Ramírez-Carracedo Rafael Moreno-Gómez-Toledano Antonio Peña-Fernández

Contemporary knee prostheses rely predominantly on a metal–polyethylene bearing couple, which—despite substantial advances in material engineering—continues to generate polymeric wear particles over time. While the local biological effects of polyethylene debris, such as inflammation and osteolysis, are well-characterised, their potential systemic implications remain insufficiently explored. In this review, we synthesise multidisciplinary evidence to evaluate the generation, biological behaviour, and systemic dissemination of polyethylene-derived nano- and microplastics (NMPs) released from knee prostheses. We also contextualise prosthetic wear within the broader toxicological framework of NMP exposure, highlighting translocation pathways, interactions with immune and metabolic systems, and potential multi-organ effects reported in recent experimental and clinical studies. Current findings suggest that prosthetic wear may represent an under-recognised internal source of NMP exposure, with possible implications for long-term patient health. A clearer understanding of the systemic behaviour of prosthetic-derived NMPs is essential to guide future biomonitoring studies, improve prosthetic materials, and support the development of safer, more biocompatible implant designs.

Micro doi: 10.3390/micro6010001

Authors: Edgar B. Sousa N. F. Cunha Joel Borges Michael Belsley

We demonstrate that pulsed laser annealing induces plasmonic gold nanoparticles in ZnO thin films, monitored in real-time via pulse-by-pulse spectroscopy. Initially embedded gold nanoparticles (smaller than 5 nm) in sputtered ZnO films were annealed using 532 nm pulses from a Q-switched Nd:YAG laser while monitoring transmission spectra in situ. A plasmonic resonance dip emerged after ~100 pulses in the 530–550 nm region, progressively deepening with continued exposure. Remarkably, different incident energies converged to a thermodynamically stable optical state centered near 555 nm, indicating robust nanoparticle configurations. After several hundred laser shots, the process stabilized, producing larger nanoparticles (40–200 nm diameter) with significant surface protrusion. SEM analysis confirmed substantial gold nanoparticle growth. Theoretical modeling supports these observations, correlating spectral evolution with particle size and embedding depth. The protruding gold nanoparticles can be functionalized to detect specific biomolecules, offering significant advantages for biosensing applications. This approach offers superior spatial selectivity and real-time process monitoring compared to conventional thermal annealing, with potential for optimizing uniform nanoparticle distributions with pronounced plasmonic resonances for biosensing applications.

Micro doi: 10.3390/micro5040060

Authors: Alibala Aliyev Aygun Israyilova Ulviyya Hasanova Zarema Gakhramanova Aida Ahmadova

The process of wound healing is intricate and regulated by a network of cellular, molecular, and biochemical pathways. Acute wounds progress via distinct phases of hemostasis, inflammation, proliferation, and remodeling. Chronic wounds frequently cease to heal and exhibit resistance to conventional therapies. These types of injuries are frequently attributed to diabetes, infection, or senescence. Existing therapies are constrained due to their ineffectiveness against bacteria, inability to promote regeneration, and inadequate control over medication release. Nanotechnology presents novel methods to overcome these challenges by providing multifunctional platforms that enable biological repair and medicinal delivery. Nanoparticles, which combat germs and modulate the immune system, in addition to being intelligent carriers that react to pH, oxidative stress, or enzymatic activity, provide targeted and adaptive wound therapy. Nanocomposite hydrogels are particularly advantageous as biointeractive dressings due to their ability to maintain wound moisture while facilitating regulated drug delivery. Recent advancements indicate their potential to aid in tissue regeneration, enhance therapy precision, and address issues related to safety and translation. Nanotechnology-based approaches, especially smart hydrogels, give significant promise to transform the future of wound care due to their flexibility, adaptability, and efficiency.

Micro doi: 10.3390/micro5040059

Authors: Luca Banchelli Rosen Mitrev Vladimir Stavrov Borislav Ganev Todor Todorov

This paper presents a theoretical and experimental investigation of the amplitude–frequency response of a triple-microcantilever system designed for real-time ultra-low mass detection. The present study focuses on the unfunctionalized configuration to clarify the intrinsic electromechanical behavior of this system. Starting with analytical expressions, output voltage amplitude–frequency responses are derived for a Wheatstone-bridge-based readout circuit and used to analyze the relationship between the resonant frequencies and mechanical amplitude–frequency responses of the three microcantilevers and the resulting electrical response. The extrema and zero-crossing points of the output voltage do not trivially coincide with the individual resonance peaks or their intersection points; this offers more freedom for defining strong detection criteria. A specialized experimental setup has been developed and used to measure the frequency response of a fabricated triple-microcantilever prototype; good agreement with the theoretical predictions has been found within the operating range. Initial humidification tests confirm the high sensitivity of the microsystem against small added masses, corresponding to an estimated detection limit on the order of 10−16 kg for the unfunctionalized device. In this way, the present work confirms the validity of the proposed triple-microcantilever configuration for ultra-low mass sensing and outlines its potential for future application in pathogen detection upon surface functionalization.

Micro doi: 10.3390/micro5040058

Authors: Jexairys Sostre-Figueroa Amanda Rodríguez-Cadiz Sonia J. Bailón-Ruiz

Zinc oxide (ZnO) nanoparticles are widely used in cosmetics, coatings, and industrial formulations due to their UV-absorbing and antimicrobial properties; however, their increasing release into aquatic systems has raised concerns about potential ecological risks. This study evaluates the acute toxicity of pure and silver-doped ZnO (Ag-ZnO) nanoparticles using Artemia salina as a marine model organism. Nanoparticles were synthesized via a reflux-assisted method and characterized by UV–Vis spectroscopy, HRTEM, ED, FTIR, and EDX analyses, confirming a crystalline wurtzite structure, particle sizes of 10–30 nm, and successful incorporation of 5% Ag. Silver doping produced a slight blue shift in the absorption edge and minor lattice distortions, indicating modifications in the electronic structure. Toxicity assays revealed clear concentration- and time-dependent decreases in nauplii survival. Dose–response modeling showed LC50 values of 358 ppm (24 h) and 64 ppm (48 h) for pure ZnO, whereas Ag-ZnO exhibited LC50 values of 607 ppm (24 h) and 28 ppm (48 h). These results indicate that Ag doping does not enhance short-term toxicity but markedly increases toxicity after prolonged exposure. Overall, the findings highlight the need to consider both nanomaterial composition and exposure duration in ecotoxicological assessments and provide relevant data for evaluating the environmental impact of doped nanomaterials in marine systems.

Micro doi: 10.3390/micro5040057

Authors: Patrice Berthod Siouare Hammi Lionel Aranda Christophe Rapin

This study investigates the effects of Ti addition on the microstructures, melting temperature ranges, thermal expansion behavior, high-temperature creep and oxidation resistances of an equimolar CoNiFeCr alloy of a foundry origin. The addition of 1.5 wt.% Ti does not really change the single-phase state of the reference quaternary alloy but induces a significant decrease in the melting start and melting end temperatures. The thermal expansion coefficient is slightly lowered. The creep resistance at 1100 °C is significantly enhanced. The oxidation at 1200 °C is controlled by species diffusion through a continuous chromia layer. The parabolic constant is higher than for the quaternary alloy, due to external and internal Ti oxidation. The presence of a thin layer of titanium oxide covering the chromia scale is suspected to limit chromia volatilization and the scale spallation at cooling. Globally, Ti demonstrated the beneficial influence of the high-temperature properties of the alloy.

Micro doi: 10.3390/micro5040056

Authors: Fareha Bano

Antimicrobial resistance (AMR) poses a global health threat, which is becoming more challenging due to the involvement of bacterial virulence mechanisms such as quorum sensing (QS) and biofilm formation. These systems regulate pathogenic traits and shield bacteria from conventional therapies. Phytocompounds offer promising antivirulence strategies by disrupting QS and biofilms without exerting selective pressure. In this study, emodin, a natural anthraquinone, was evaluated for its anti-QS and antibiofilm efficacy. Emodin inhibited violacein production by 63.86% in C. violaceum 12472. In P. aeruginosa PAO1, it suppressed pyocyanin (68.04%), pyoverdin (48.79%), exoprotease (58.55%), elastase (43.13%), alginate (74.12%), and rhamnolipids (56.37%). In S. marcescens MTCC 97, emodin reduced prodigiosin (55.94%), exoprotease (48.80%), motility (83.27%), and cell surface hydrophilicity (41.20%). Biofilm formation was inhibited by over 50% in all three bacteria, highlighting emodin’s potential as a broad-spectrum antibiofilm agent. Molecular docking analyses indicated that emodin exhibited affinity towards QS regulatory proteins CviR, LasR, and SmaR, implying a possible competitive interaction at their ligand-binding sites. Subsequent molecular dynamics simulations confirmed these observations by demonstrating structural stability in emodin-bound proteins. The collective insights from in vitro assays and computational studies underscore the potential of emodin in interfering with QS-mediated virulence expression and biofilm development. Such findings support the exploration of non-antibiotic QS inhibitors as therapeutic alternatives for managing bacterial infections and reducing dependence on traditional antimicrobial agents.

Micro doi: 10.3390/micro5040055

Authors: Quan Truong Nguyen Phuong Thi Thu Pham Uyen Thu Pham Duong Thanh Nguyen Trung Thanh Luu Doanh Van Nguyen

Background: Copper nanoparticles (CuNPs) are promising antibacterial agents, but instability and heterogeneity in ‘green’ routes limit translation. Methods: We developed a one-step synthesis in which pre-polymerized polycatechin acts as both reductant and capping agent to form copper–polycatechin core–shell nanoparticles (Cu@polycat). Physicochemical properties (TEM/DLS/XRD/FTIR/ζ), colloidal stability (pH, salt, serum), ion release, and antibacterial activity against planktonic and biofilm E. coli/S. aureus were evaluated. Results: Cu@polycat featured a ~21.5 nm metallic core and ~45 nm hydrodynamic diameter (shell ≈ 12 nm, estimated from TEM–DLS) with ζ ≈ −34 mV, conferring high stability across physiological conditions. Cu@polycat outperformed uncoated CuNPs, displaying 8-fold lower MICs and rapid bactericidal kinetics (>5-log10 in 6–8 h). Synergy between the copper core and polycatechin corona was confirmed (FICI ≈ 0.08). Cu@polycat inhibited biofilm formation by >80% and reduced viable counts in 24 h mature biofilms by ≥3-log10, whereas ampicillin was ineffective under the same biofilm conditions. Conclusions: A polycatechin-based green route furnishes a stable, synergistic nano-antibacterial platform with potent anti-biofilm activity, supporting development for wound-care and anti-fouling device coatings.

Micro doi: 10.3390/micro5040054

Authors: S. Mytreyi Sharanappa Chapi Sutar Rani Ananda Nagaraj Nandihalli M. V. Murugendrappa

The current research presents the synthesis, characterization, and application of a novel gas sensor based on polypyrrole/strontium titanate (PPy/STO) nanocomposites for the selective detection of CO2. Utilizing chemical oxidative polymerization, PPy and PPy/STO nanocomposites with varying STO (10–50) wt.% were synthesized and characterized. The structural and morphological analysis confirms the formation of spherical structure and well-dispersed PPy nanoparticles with increasing crystallinity and interaction of STO in PPy chain particle compactness as the STO content increases. The integration of perovskite STO within the conducting polymer matrix enhances the electronic structure, porosity, and surface area of the composite, promoting improved gas sensing performance. Electrical impedance spectroscopy reveals that the composites exhibit a frequency-dependent dielectric response and conduction attributed to charge carrier mobility and interfacial polarization effects. PPy/STO 20% exhibits highest conductivity and dielectric constants of 0.03604 Scm−1 and 1.074 × 104, respectively. Real-time CO2 sensing experiments conducted at 50 °C demonstrate good sensitivity, stability, and rapid response/recovery characteristics, particularly for the PPy/STO 10% and 40% composites. These findings highlight the potential of PPy/STO nanocomposites as flexible, lightweight, and efficient materials for portable CO2 gas sensors, addressing the growing needs for environmental and health monitoring.

Micro doi: 10.3390/micro5040053

Authors: Dan Li Hong Li Yilin Wei Lu Jiang Hongqing Feng Qiang Zheng

Developing conductive hydrogels that balance high conductivity, stretchability, transparency, and sensitivity for next-generation wearable sensors remains challenging due to inherent trade-offs. This study introduces a straightforward approach to fabricate a semi-interpenetrating double-network hydrogel comprising polyvinyl alcohol (PVA), polyacrylamide (PAM), and lithium chloride (LiCl) to overcome these limitations. Leveraging hydrogen bonding for energy dissipation and chemical cross-linking for structural integrity, the design achieves robust mechanical properties. The incorporation of 1 mol/L LiCl significantly enhances ionic conductivity, while also providing plasticizing and moisture-retention benefits. The optimized hydrogel exhibits impressive ionic conductivity (0.47 S/m, 113% enhancement), excellent mechanical performance (e.g., 0.177 MPa tensile strength, 730% elongation, 0.68 MJ m−3 toughness), high transparency (>85%), and superior strain sensitivity (gauge factors ~1). It also demonstrates rapid response/recovery and robust fatigue resistance. Functioning as a wearable sensor, it reliably monitors diverse human activities and enables novel, secure data handling applications, such as finger-motion-driven Morse code interfaces and gesture-based password systems. This accessible fabrication method yields versatile hydrogels with promising applications in health tracking, interactive devices, and secure communication technologies.

Micro doi: 10.3390/micro5040052

Authors: Elçin Tören Jakub Wiener

This study investigates electrospinning methodologies using distilled water as an environmentally friendly and non-toxic solvent for fabricating nanofibers composed of fish collagen (COL) and pullulan (PUL). The underlying hypothesis is that incorporating PUL will enhance the spinnability of the electrospun solution through the formation of hydrogen bonds with COL, thereby facilitating improved fiber development within an aqueous system. This study examined the interactions between COL and PUL molecules, focusing on hydrogen bonding and the consequential alterations in secondary structural conformation, to elucidate their effects on the spinnability and stability of COL in water-based solutions. Furthermore, this study emphasizes the advantages of needle-free electrospinning, which enables the efficient production of nanofibers and offers scalability potential for industrial applications. The architecture and properties of the resultant ultra-thin COL/PUL fibers were comprehensively characterized, underscoring their suitability for various biomedical applications. The development of PUL-based skin nanofibers represents a significant advancement in the field of biomaterials, offering a biocompatible and biodegradable alternative for dermatological applications, including skin regeneration, wound healing, drug delivery, tissue engineering, and cosmetic science. The benefits of needle-free electrospinning, such as enhanced production efficiency and scalability, are particularly emphasized, demonstrating its potential for the large-scale commercial manufacturing of biocompatible nanofibers. This study aimed to address the research gap regarding the use of distilled water as an eco-friendly and safe solvent for electrospinning nanofibers made from collagen and pullulan. This study aimed to investigate the unexplored potential of distilled water for this application.

Micro doi: 10.3390/micro5040051

Authors: Mauro Difeo Leandro Ramajo Miriam Castro

This work presents a comparative study on the structural, microstructural, and functional properties of a novel lead-free solid solution based on (1−x)(0.95(Bi0.5Na0.5)TiO3–0.05BaTiO3)–x(0.5Ba0.7Ca0.3TiO3–0.5BaTi0.8Zr0.2O3), abbreviated as (1−x)(BNT–5BT)–xBCZT, with x values ranging from 0 to 0.20. Two different synthesis routes were evaluated: a direct route, where all raw materials were mixed and processed in a single step, and an indirect route, where BNT–5BT and BCZT were pre-synthesized separately and later combined. X-ray diffraction (XRD) and Raman spectroscopy confirmed the formation of single-phase perovskite structures, with progressively increasing tetragonality as x increased. Field-emission scanning electron microscopy (FE-SEM/EDS) revealed dense microstructures and secondary rod-like phases whose morphology and amount evolved with composition. Dielectric measurements indicated an enhanced relaxor behavior with increasing BCZT content, evidenced by a shift in the TF–R with frequency. The direct route resulted in more efficient dopant incorporation, leading to stronger dielectric relaxation, reduced hysteresis losses, and improved energy storage performance. The maximum energy efficiency (η) reached 43.7% for x = 0.075 via the direct route, compared to 38.0% for the same composition prepared by the indirect route. The maximum recoverable energy density (Wrec) reached 0.42 J·cm−3 for x = 0.075 via the direct route (vs. 0.40 J·cm−3 for the indirect route), with corresponding peak energy efficiencies of 43.7% and 38.0%, respectively. These findings demonstrate that (1−x)(BNT–5BT)–xBCZT ceramics synthesized via the direct route constitute a promising and scalable approach for high-efficiency, lead-free dielectric capacitors.

Micro doi: 10.3390/micro5040050

Authors: Vijayan Malavika Muthuswami Ruby Rajan Raman Krishnamoorthi Kozhikamabath Chandrasekharan Adithya Kwang-sun Kim

Carbon quantum dots (CQDs) are photoluminescent nanomaterials (<10 nm) with excellent hydrophilicity, biocompatibility, and low cytotoxicity, making them attractive for biological applications. However, their use in aquaculture nutrition has remained largely unexplored. This study investigated the effects of dietary CQDs on zebrafish (Danio rerio), a model organism with approximately 70% genetic homology with humans. CQDs were synthesized hydrothermally from unripe Citrus limon and characterized by UV–visible (UV-Vis) spectroscopy, UV–vis transillumination, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FT-IR), and photoluminescence (PL) spectroscopy. Zebrafish were fed diets containing varying CQD concentrations, and growth performance, condition factor (K), hematological parameters, enzymatic activity, and tissue morphology were assessed. Feeds supplemented with 2 mL CQDs produced significant improvements in growth and biochemical indicators without adverse effects. Hematological and enzymatic profiles remained within normal ranges, and histological examination revealed no morphological abnormalities, indicating the absence of toxicity. These findings suggest that citrus-derived CQDs can enhance zebrafish growth and maintain physiological health, thereby supporting their potential as safe functional feed additives in aquaculture. This approach may open new opportunities for the application of CQDs in sustainable fish farming and the broader food industry.

Micro doi: 10.3390/micro5040049

Authors: Zdeněk Slanina Filip Uhlík Takeshi Akasaka Xing Lu Ludwik Adamowicz

Dy@C82 is one of the metallofullerenes studied as dopants for improvements of stability and performance of solar cells. Calculations should help in formulating rules for selections of fullerene endohedrals for such new applications in photovoltaics. Structure, energetics, and relative equilibrium populations of two potential-energy-lowest IPR (isolated pentagon rule) isomers of Dy@C82 under high synthetic temperatures are calculated using the Gibbs energy based on molecular characteristics at the B3LYP/6-31G*∼SDD level. Dy@C2v(9)-C82 and Dy@Cs(6)-C82 are calculated as 58 and 42%, respectively, of their equilibrium mixture at a synthetic temperature of 1000 K, in agreement with observations. The Dy@C2v(9)-C82 species is found as lower in the potential energy by 1.77 kcal/mol compared to the Dy@Cs(6)-C82 isomer.

Micro doi: 10.3390/micro5040048

Authors: Jannah Urifa Kwok Wei Shah

Hydrogel microneedles (HMNs) act as non-invasive devices that can effortlessly merge with the human body for drug delivery and diagnostic purposes. Nonetheless, their improvement is limited by intricate and repetitive issues related to material composition, structural geometry, manufacturing accuracy, and performance enhancement. At present, there are only a limited number of studies accessible since artificial intelligence and machine learning (AI/ML) for HMN are just starting to emerge and are in the initial phase. Data is distributed across separate research efforts, spanning different fields. This review aims to tackle the disjointed and narrowly concentrated aspects of current research on AI/ML applications in HMN technologies by offering a cohesive, comprehensive synthesis of interdisciplinary insights, categorized into five thematic areas: (1) material and microneedle design, (2) diagnostics and therapy, (3) drug delivery, (4) drug development, and (5) health and agricultural sensing. For each domain, we detail typical AI methods, integration approaches, proven advantages, and ongoing difficulties. We suggest a systematic five-stage developmental pathway covering material discovery, structural design, manufacturing, biomedical performance, and advanced AI integration, intended to expedite the transition of HMNs from research ideas to clinically and commercially practical systems. The findings of this review indicate that AI/ML can significantly enhance HMN development by addressing design and fabrication constraints via predictive modeling, adaptive control, and process optimization. By synchronizing these abilities with clinical and commercial translation requirements, AI/ML can act as key facilitators in converting HMNs from research ideas into scalable, practical biomedical solutions.

Micro doi: 10.3390/micro5040047

Authors: James L. Thomason Roya Akrami Liu Yang

Size is a surface coating applied to glass fibres during manufacture, and it is arguably the most important component in a glass-reinforced composite. Research and development on sizings and composite interfaces are severely limited, because conventional laboratory- scale glass fibre sizing analysis commonly involves sample preparation by dip coating, resulting in a size layer up to two orders of magnitude thicker than industrially produced glass fibre products. This makes it difficult to make useful comparisons between industrial and lab-scale-prepared samples when investigating size performance. This paper presents a novel, but simple, use of laboratory spin coating to apply a size layer to glass fibres that are similar to industrial-sized fibres. Thermogravimetric analysis and electron microscopy were used to investigate the size layers of glass fibres spin-coated with two chemically different sizing formulations, under a range of conditions. The average size layer thickness on spin-coated glass fibres could be easily and simply controlled in a range from 0.05 to 0.6 µm, compared to 0.4–1.3 µm on samples dip coated with the same size formulation and 0.06–0.10 µm on industrial reference samples. This novel application of the spin coating method offers the potential of improved research sample preparation, as it eliminates the need to alter the concentration of the sizing formulations to unacceptably low levels to obtain normal size layer thicknesses.

Micro doi: 10.3390/micro5040046

Authors: Dimitris Kalatzis Angeliki I. Katsafadou Dimitrios Chatzopoulos Charalambos Billinis Yiannis Kiouvrekis

Raman spectroscopy is a rapid, label-free, and non-destructive technique for probing molecular structures, making it a powerful tool for clinical pathogen identification. However, interpreting its complex spectral data remains challenging. In this study, we evaluate and compare a suite of machine learning models—including Support Vector Machines (SVM), XGBoost, LightGBM, Random Forests, k-nearest Neighbors (k-NN), Convolutional Neural Networks (CNNs), and fully connected Neural Networks—with and without Principal Component Analysis (PCA) for dimensionality reduction. Using Raman spectral data from 30 clinically important bacterial and fungal species that collectively account for over 90% of human infections in hospital settings, we conducted rigorous hyperparameter tuning and assessed model performance based on accuracy, precision, recall, and F1-score. The SVM with an RBF kernel combined with PCA emerged as the top-performing model, achieving the highest accuracy (0.9454) and F1-score (0.9454). Ensemble methods such as LightGBM and XGBoost also demonstrated strong performance, while CNNs provided competitive results among deep learning approaches. Importantly, interpretability was achieved via SHAP (Shapley Additive exPlanations), which identified class-specific Raman wavenumber regions critical to prediction. These interpretable insights, combined with strong classification performance, underscore the potential of explainable AI-driven Raman analysis to accelerate clinical microbiology diagnostics, optimize antimicrobial therapy, and improve patient outcomes.

Micro doi: 10.3390/micro5040045

Authors: Ali Jabbar Abd Al-Hussain Alkawaz Maryam Sabah Naser Ali Jalil Obaid

Introduction: Hospital-acquired infections remain a significant healthcare concern due to the persistence of pathogens such as Staphylococcus aureus and Escherichia coli on frequently touched surfaces. Conventional TiO2 coatings are limited to UV activation, which restricts their application under normal indoor light. Combining TiO2 with ZnO and employing green synthesis methods may overcome these limitations. Methodology: Biogenic TiO2 and ZnO nanoparticles were synthesized using Bacillus subtilis under mild aqueous conditions. The nanoparticles were characterized by SEM, XRD, UV-Vis, and FTIR, confirming nanoscale size, crystalline phases, and organic capping. A multilayer TiO2/ZnO coating was fabricated on glass substrates through layer-by-layer deposition. Antibacterial activity was tested against S. aureus and E. coli using disk diffusion, direct contact assays, ROS quantification (FOX assay), and scavenger experiments. Statistical significance was evaluated using ANOVA. Results: The TiO2/ZnO multilayer exhibited superior antibacterial activity under visible light, with inhibition zones of ~15 mm (S. aureus) and ~12 mm (E. coli), significantly outperforming single-component coatings. Direct contact assays confirmed strong bactericidal effects, while scavenger tests verified ROS-mediated mechanisms. FOX assays detected elevated H2O2 generation, correlating with antibacterial performance. Discussion: Synergistic effects of band-gap narrowing, Zn2+ release, and ROS generation enhanced visible-light photocatalysis. The multilayer structure improved light absorption and charge separation, providing higher antimicrobial efficacy than individual oxides. Conclusion: Biogenic TiO2/ZnO multilayers represent a sustainable, visible-light-activated antimicrobial strategy with strong potential for reducing nosocomial infections on hospital surfaces and surgical instruments. Future studies should assess long-term durability and clinical safety.

Micro doi: 10.3390/micro5040044

Authors: Zohurul Islam Khalid Bin Kaysar Shakhawat Hossain Akram Hossain Suvash C. Saha Toufik Tayeb Naas Kwang-Yong Kim

The enhancement of drug delivery into the lung surfactant is facilitated by research on the interaction between drugs and the lung surfactant. Drug designers must have a thorough theoretical understanding of a drug before performing clinical tests to reduce the experimental cost. The current study uses a coarse-grained molecular dynamics (MD) approach with the MARTINI force field to parameterize the corticosteroid drug mometasone furoate, which is used to treat lung inflammation. Here, we investigate the accurate parametrization of drug molecules and validate the parameters with the help of umbrella sampling simulations. A collection of thermodynamic parameters was studied during the parametrization procedure. The Gibbs free energy gradient was used to calculate the partition coefficient value of mometasone furoate, which was approximately 10.49 based on our umbrella sampling simulation. The value was then matched with the experimental and predicted the partition coefficient of the drug, showing good agreement. The drug molecule was then delivered into the lung surfactant monolayer membrane at the alveolar air–water interface, resulting a concentration-dependent drop in surface tension while controlling the underlying continual compression–expansion of alveoli that maintains the exhalation–inhalation respiratory cycle. The dynamical properties of the monolayer demonstrate that the drug’s capacity to diffuse into the monolayer is considerably diminished in larger clusters, and this effect is intensified when there are more drug molecules present in the monolayer. The monolayer microstructure analysis shows that the drug concentration controls monolayer morphology. The results of this investigation may be helpful for corticosteroid drug delivery into the lung alveoli, which can be applied to comprehend how the drug interacts with lung surfactant monolayers or bilayers.

Micro doi: 10.3390/micro5030043

Authors: Catherine Beale Andrew Turner

Microplastics (MPs) are ubiquitous and persistent contaminants of the marine environment, but a clear understanding of their cycling, fate, and impacts in coastal zones is lacking. In this study, large MPs (1–5 mm) were sampled spatially and temporally from the strandline of a macrotidal, sandy beach (Polzeath) in southwest England. MPs encompassing a diversity of sources were categorised by morphology (foams, nurdles, biobeads, fragments, fibres, films) and quantified by number and mass, with a selection analysed for polymer type. A total of about 17,600 particles of around 350 g in mass were retrieved from 30 samples over a period of five months, with an abundance ranging from 35 and 2048 per m2. The space- and time-integrated average mass of MPs on the beach strandline was about 2 kg and was dominated (>90%) by fragments, nurdles, and biobeads of polyethylene or polypropylene construction. Nurdles, biobeads, fragments, and, to a lesser extent, fibres were correlated with strandline seaweed abundance, which itself was correlated with previous storm activity. Relationships with seaweed abundance were also supported by visible associations of these MP morphologies with macroalgal deposits through entanglement and adhesion. These observations, coupled with a lack of MPs below the sand’s surface (50 cm depth), suggest that the majority of MPs are transported from an offshore stock with floating organic debris, resulting in a transitory strandline repository and a habitat enriched with small plastics.

Micro doi: 10.3390/micro5030042

Authors: Kentaro Tanagi Anuj Tiwari Sho Kawaharada Shunya Okamoto Takayuki Shibata Tuhin Subhra Santra Moeto Nagai

High-throughput biological and chemical assays increasingly require parallel sample manipulation using arrays of micronozzle apertures. Liquid-to-liquid ejection avoids air–liquid interfaces, thereby reducing sample evaporation and mechanical stress while simplifying device operation. However, existing microfluidic platforms for parallel handling suffer from high dead volume, limited optical access, and poor scalability due to thick structural layers. Here, we present a transparent three-layer 4 × 4 micronozzle array with 40 μm diameter openings and a photolithographically fabricated SU-8 membrane. Our sacrificial layer process yields a 30 µm SU-8 membrane—approximately a 70% reduction in thickness—thereby lowering vertical channel dead volume and eliminating the need for costly glass etching. The resulting architecture enables parallel particle and nanoliter liquid manipulation with real-time optical clarity and enables water-to-water ejection, avoiding air–liquid interfaces. This work demonstrates the water-to-water ejection of 0.5–10 µm microparticles using a transparent, low-dead volume SU-8/PDMS micronozzle array and provides a basis for future studies on substrate deposition and cell handling workflows.

Micro doi: 10.3390/micro5030041

Authors: Hassan Arif Sachi Mehta Isaac Macwan

p53 protein is a nuclear phosphoprotein that is a critical tumor suppressor, playing a key role in regulating the cell cycle and initiating apoptosis in response to DNA damage. As a transcription factor, it also activates genes involved in DNA repair and cell cycle arrest. H2AX is a histone H2A variant, which is vital for detecting DNA double-strand breaks. When phosphorylated at Serine 139, it forms γH2AX, which recruits DNA repair proteins to damage sites. The interaction between p53 and γH2AX is central to the DNA damage response, where p53 activates repair pathways and γH2AX flags the DNA lesions. It is known that impairing γH2AX while preserving p53 activity may slow cancer progression. Towards understanding this, graphene quantum dots (GQDs) offer a promising solution for tracking γH2AX and analyzing DNA damage, where they can help visualize it by investigating how p53 contributes to DNA repair at sites marked by γH2AX. This study examines the interactions between γH2AX and p53 with three different-sized two-layered GQDs (2 × 3 nm, 5 × 6 nm, and 8 × 9 nm) using the Molecular Dynamics (MD) approach. Our analysis revealed that both proteins adsorbed strongly to the 5 × 6 nm and 8 × 9 nm GQDs, with 5 × 6 nm GQD having the highest stability, making it a key candidate for future biosensing and cancer research, whereas the 8 × 9 nm GQD has the greatest potential to denature the proteins.

Micro doi: 10.3390/micro5030040

Authors: Joys Alisa Angelina Hutapea Yosia Gopas Oetama Manik Sun Theo Constan Lotebulo Ndruru Jingfeng Huang Ronn Goei Alfred Iing Yoong Tok Rikson Siburian

Graphene, a two-dimensional material with remarkable electrical, thermal, and mechanical properties, has revolutionized the fields of electronics, energy storage, and nanotechnology. This review presents a comprehensive analysis of graphene synthesis techniques, which can be classified into two primary approaches: top-down and bottom-up. Top-down methods, such as mechanical exfoliation, oxidation-reduction, unzipping carbon nanotubes, and liquid-phase exfoliation, are highlighted for their scalability and cost-effectiveness, albeit with challenges in controlling defects and uniformity. In contrast, bottom-up methods, including chemical vapor deposition (CVD), arc discharge, and epitaxial growth on silicon carbide, offer superior structural control and quality but are often constrained by high costs and limited scalability. The interplay between synthesis parameters, material properties, and application requirements is critically examined to provide insights into optimizing graphene production. This review also emphasizes the growing demand for sustainable and environmentally friendly approaches, aligning with the global push for green nanotechnology. By synthesizing current advancements and identifying critical research gaps, this work offers a roadmap for selecting the most suitable synthesis techniques and fostering innovations in scalable and high-quality graphene production. The findings serve as a valuable resource for researchers and industries aiming to harness graphene’s full potential in diverse technological applications.

Micro doi: 10.3390/micro5030039

Authors: Edith Dube Grace Emily Okuthe

The growing threat of antimicrobial resistance has necessitated the development of alternative, non-antibiotic therapies for effective microbial control. Antimicrobial photodynamic therapy, which uses photosensitizers activated by light to generate reactive oxygen species, offers a promising solution. Among natural photosensitizers, curcumin, a polyphenolic compound from Curcuma longa, has demonstrated broad-spectrum antimicrobial activity through reactive oxygen species-mediated membrane disruption and intracellular damage. However, curcumin’s poor water solubility, low stability, and limited bioavailability hinder its clinical utility. Nanotechnology has emerged as a transformative strategy to overcome these limitations. This review comprehensively explores advances in nanocurcumin- and curcumin-loaded nanoparticles, highlighting their physicochemical enhancements, photodynamic mechanisms, and antimicrobial efficacy against multidrug-resistant and biofilm-associated pathogens. A range of nanocarriers, including chitosan, liposomes, nanobubbles, hybrid metal composites, metal–organic frameworks, and covalent organic frameworks, demonstrate improved microbial targeting, light activation efficiency, and therapeutic outcomes. Applications span wound healing, dental disinfection, food preservation, water treatment, and medical device sterilization. Conclusions and future directions are given, emphasizing the integration of smart nanocarriers and combinatorial therapies to enhance curcumin’s clinical translation.

Micro doi: 10.3390/micro5030038

Authors: Hairuo Zhu Kangyu Liu Zhaorui Meng Huanhuan Wang Yuming Li

Nanomaterials are materials in which at least one dimension in three-dimensional space is at the nanoscale. In recent years, nano-alumina has attracted much attention due to its large specific surface area and pore volume, as well as novel optical, magnetic, electronic, and catalytic properties. This review summarizes the preparation methods of nano-alumina based on the basic phases and properties of alumina materials, focusing on one-dimensional, two-dimensional, and three-dimensional nano-alumina preparation methods, which can provide some theoretical guidance for the subsequent development of efficient nano-alumina materials. Finally, the application of nano-alumina materials in catalysis is reviewed, and some suggestions are provided for improving the use of nano-alumina in the catalysis field.

Micro doi: 10.3390/micro5030037

Authors: Iliana Ntovolou Despoina Farkatsi Kosmas Ellinas

Over the last few decades, the growing demand for sustainable resources has made biopolymers increasingly popular, as they offer an eco-friendly alternative to conventional synthetic polymers, which are often associated with environmental issues such as the formation of microplastics and toxic substances. Functionalization of biomaterials involves modifying their physical, chemical, or biological properties to improve their performance for specific applications. Cellulose and bacterial cellulose are biopolymers of interest, due to the plethora of hydroxyl groups, their high surface area, and high porosity, which makes them ideal candidates for several applications. However, there are applications, which require precise control of their wetting properties. In this review, we present the most effective fabrication methods for modifying both the morphology and the chemical properties of cellulose and bacterial cellulose, towards the realization of superhydrophobic bacterial cellulose films and surfaces. Such materials can find a wide variety of applications, yet in this review we target and discuss applications deriving from the wettability control, such as antibacterial surfaces, wound healing films, and separation media.

Micro doi: 10.3390/micro5030036

Authors: Therys Senna de Castro Oliveira Jhonathan Valente Ferreira Gusmão Thaís Caroline Buttow Rigolon Daiana Wischral Pedro Henrique Campelo Evandro Martins Paulo Cesar Stringheta

The encapsulation of bioactive compounds using proteins as wall materials has emerged as an effective strategy to enhance their stability, bioavailability, and controlled release. Proteins offer unique functional properties, including amphiphilic behavior, gel-forming ability, and interactions with bioactives, making them ideal candidates for encapsulation. Animal-derived proteins, such as whey and casein, exhibit superior performance in stabilizing lipophilic compounds, whereas plant proteins, including soy and pea protein, demonstrate greater affinity for hydrophilic bioactives. Advances in protein modification and the formation of protein–polysaccharide complexes have further improved encapsulation efficiency, particularly for heat- and pH-sensitive compounds. This review explores the physicochemical characteristics of proteins used in encapsulation, the interactions between proteins and bioactives, and the main encapsulation techniques, including spray drying, complex coacervation, nanoemulsions, and electrospinning. Furthermore, the potential applications of encapsulated bioactives in functional foods, pharmaceuticals, and nutraceuticals are discussed, highlighting the role of emerging technologies in optimizing delivery systems. Understanding the synergy between proteins, bioactives, and encapsulation methods is essential for developing more stable, bioavailable, and sustainable functional products.

Micro doi: 10.3390/micro5030035

Authors: Mauro Difeo Miriam Castro Leandro Ramajo

This study evaluates the effect of zirconium (Zr) incorporation on the structural, microstructural, and functional properties of lead-free ceramics based on the 0.95(Bi0.5Na0.5)TiO3–0.05BaTiO3 (BNT–5BT) system. Two distinct doping strategies were investigated: (i) the substitutional incorporation of Zr4+ at the Ti4+ site (BNT–5BT–xZrsub), and (ii) the addition of ZrO2 in excess (BNT–5BT–xZrexc). The samples were synthesized via conventional solid-state reaction and characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM/EDS), and electrical measurements, including dielectric, ferroelectric, and piezoelectric responses. Both doping routes were found to influence phase stability and electromechanical performance. Substitutional doping notably reduced the coercive field while preserving high remanent polarization, resulting in an enhanced piezoelectric coefficient (d33). These results highlight the potential of Zr-modified BNT–5BT ceramics for lead-free energy harvesting applications.

Micro doi: 10.3390/micro5030034

Authors: Polyxeni Vourna Pinelopi P. Falara Nikolaos D. Papadopoulos

Antifouling coatings are integral to the maritime economy. The efficacy of the applied painting system is closely correlated with susceptibility to fouling and the adhesion strength of contaminants. A fouled hull might result in an elevated fuel consumption and journey expenses. Biofouling on ship hulls also has detrimental environmental consequences due to the release of biocides during maritime travel. Therefore, it is imperative to develop eco-friendly antifouling paints that inhibit the robust adhesion of marine organisms. This study aimed to assess a biocide-free antifouling coating formulated with polymers intended to diminish molecular adhesion interactions between marine species’ adhesives and the coating. The evaluation included laboratory corrosion experiments in artificial seawater and the immersion of samples in a marine environment in Attica, Greece, for varying durations. The research indicates that an antifouling coating applied to naval steel in an artificial seawater solution improves corrosion resistance by more than 60%. The conductive polymer covering, comprising polyaniline and graphene oxide, diminishes corrosion current values, lowers the corrosion rate, and enhances corrosion potentials. The impedance parameters exhibit analogous behavior, with the coating preventing water absorption and displaying corrosion resistance. The coating serves as a low-permeability barrier, exhibiting exceptional durability for naval steel over time, with an operational performance up to 98%.

Micro doi: 10.3390/micro5030033

Authors: Hala Al-Jawhari Nuha A. Alhebshi Roaa Sait Reem Altuwirqi Laila Alrehaili Noorah Al-Ahmadi Nihal Elbialy

Free-standing copper oxide (Cu2O)-copper hydroxide (Cu(OH)2) nanocomposites with enhanced catalytic and antibacterial functionalities were synthesized on copper mesh using a green method based on spinach leaf extract and glycerol. EDX, SEM, and TEM analyses confirmed the chemical composition and morphology. The resulting Cu2O-Cu(OH)2@Cu mesh exhibited notable hydrophobicity, achieving a contact angle of 137.5° ± 0.6, and demonstrated the ability to separate thick oils, such as HD-40 engine oil, from water with a 90% separation efficiency. Concurrently, its photocatalytic performance was evaluated by the degradation of methylene blue (MB) under a weak light intensity of 5 mW/cm2, achieving 85.5% degradation within 30 min. Although its application as a functional membrane in water treatment may raise safety concerns, the mesh showed significant antibacterial activity against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria under both dark and light conditions. Using the disk diffusion method, strong bacterial inhibition was observed after 24 h of exposure in the dark. Upon visible light irradiation, bactericidal efficiency was further enhanced—by 17% for S. aureus and 2% for E. coli. These findings highlight the potential of the Cu2O-Cu(OH)2@Cu microfibers as a multifunctional membrane for industrial wastewater treatment, capable of simultaneously removing oil, degrading organic dyes, and inactivating pathogenic bacteria through photo-assisted processes.

Micro doi: 10.3390/micro5030032

Authors: Perla J. Vázquez-González Martha L. Paniagua-Chávez Rafael Mota-Grajales Carlos A. Hernández-Gutiérrez

In this work, we present the development and validation of an automated system for the Successive Ionic Layer Adsorption and Reaction (SILAR) method, aimed at depositing Cu2ZnSnS4 (CZTS) thin films. The system is based on a Raspberry Pi Pico microcontroller programmed in Micro-Python (Thonny 4.0.2), allowing precise control over immersion sequences, timing intervals, and substrate positioning along two degrees of freedom. Automation enhances reproducibility, safety, and reduces human error compared with manual operation. CZTS films were deposited on borosilicate glass and optically and structurally characterized. A gradual darkening of the films with increasing deposition cycles indicates controlled material accumulation. X-ray diffraction (XRD) and Raman spectroscopy confirmed the presence of CZTS phases, although with a partially amorphous structure. The estimated optical bandgap of ~1.34 eV is consistent with photovoltaic applications. These results validate the functionality of the automated SILAR platform for repeatable and scalable thin-film fabrication, offering a low-cost alternative for producing semiconductor absorber layers in solar energy technologies.

Micro doi: 10.3390/micro5030031

Authors: Sonia J. Bailon-Ruiz Yarilyn Cedeño-Mattei Luis Alamo-Nole

This study reports the synthesis, structural characterization, adsorption studies, nanoscale interaction, and photocatalytic application of pure and Fe-doped ZnS quantum dots for the degradation of the antibiotic cefalexin in aqueous solution. Nanoparticles were synthesized via the microwave-assisted method, and Fe doping was introduced at a 1% molar ratio. HRTEM images confirmed quasi-spherical morphology and high crystallinity, with particle sizes averaging 2.4 nm (pure) and 3.5 nm (doped). XRD analysis showed a consistent cubic ZnS structure. UV-vis spectra showed strong absorption at 316 nm for both samples, and PL measurements revealed emission quenching upon Fe doping. Photocatalytic tests under UV light demonstrated significantly higher degradation rates of 10 ppm cefalexin with Fe-doped ZnS, reaching near-complete removal within 90 min. Adsorption experiments revealed higher affinity and adsorption capacity of Fe-doped ZnS toward cefalexin compared to pure ZnS, as demonstrated by the Freundlich isotherm analyses, contributing significantly to enhanced photocatalytic degradation performance. High-resolution QTOF LC-MS analysis confirmed the breakdown of the β-lactam and thiazolidine rings of cefalexin and the formation of low-mass degradation products, including fragments at m/z 122.0371, 116.0937, and 318.2241. These findings provide strong evidence for the structural destruction of the antibiotic and validate the enhanced photocatalytic performance of Fe-doped ZnS.

Micro doi: 10.3390/micro5020030

Authors: Alyona B. Kuznetsova Valentina I. Gorbacheva Ekaterina P. Kolesova Vera S. Egorova

In the tumor microenvironment, M2 tumor-associated macrophages play a crucial role in promoting tumor growth, vascularization, and metastasis through their anti-inflammatory and tissue-repairing functions. To reprogram M2 cells into a more benign M1 phenotype and enhance the patient’s intrinsic immune response against cancer, siRNA and small molecules are used, which can be encapsulated into nanoparticles to enhance their stability, circulation time, and bioavailability. Albumin nanoparticles are ideal candidates for the delivery of such cargo because of their low toxicity, biocompatibility, biodegradability, prolonged circulation in the bloodstream, and feasible particle modification. In this study, we optimized a one-step desolvation method using the standard cross-linker glutaraldehyde and D-mannose as a second cross-linker for the synthesis of mannosylated albumin nanoparticles. The obtained nanoparticles demonstrated favorable physical characteristics, high encapsulation efficiency, and the most effective targeting into activated M2 macrophages overexpressing the mannose receptor in comparison to M1 macrophages and cancer cells in vitro.

Micro doi: 10.3390/micro5020029

Authors: Mileah Metcalf Abhishu Chand Kyoungtae Kim

Quantum dots (QDs) are nanoparticles with intrinsic fluorescence. Recent studies have found that metal-based QDs often impart toxic effects on the biological systems they interact with. Their undefined limitations have offset their potential for biomedical application. Our study aimed to address the research gap regarding QDs’ impacts on the intracellular actin cytoskeleton and the associated structures. Our XTT viability assays revealed that QDs only reduced viability in transformed human liver epithelial (THLE-2) cells, whereas HeLa cells remained viable after QD treatment. We also used confocal microscopy to evaluate the morphological changes in THLE-2 induced by QDs. We further investigated cell protrusion morphology using phalloidin-Alexa488 which selectively labels F-actin. The fluorescent microscopy of this phalloidin label revealed that QD treatment resulted in the redistribution of actin filaments within both THLE-2 and HeLa cells. We also report that the average number of focal adhesions decreased in QD-treated cells. As actin filaments at the cell are peripherally linked to the extracellular matrix via talin and integrin and are thus a crucial component of cell motility, we conducted a migration assay. The migration assay revealed that cell motility was significantly reduced in both THLE-2 and HeLa cells following QD treatment. Our findings establish that the internalization of QDs reduces cell motility by rearranging actin filaments.

Micro doi: 10.3390/micro5020028

Authors: Shuza Binzaid Abhitej Divi

The greenhouse effect, responsible for trapping heat in Earth’s atmosphere, has a parallel thermal phenomenon at the indoor scale known as the Room-Level Greenhouse Effect (RGHE), where solar radiation elevates room temperatures and increases energy consumption. The RGHE contributes to indoor temperature increases of 4–10 °C and elevates energy demands by 15–30% in high solar exposure zones, the effect being even worse in tropical zones. To address this problem, an innovative analog microarchitecture is proposed for real-time RGHE detection by sensing the sunlight intensity radiation factor (SIR). A compact analog system is introduced, comprising three stages: a Sensing Circuit Stage (SCS) that isolates the dynamic sunlight signal f (r) from static room condition factors (RCFs), an Amplification Stage (AS) that shifts and boosts the signal, and a Stabilized Peak Detection Stage (SPDS) that captures the peak solar intensity. The microsystem was tested across fixed f (m) levels of 0.75 V, 1.0 V, and 1.5 V, and varying f (r) values of 3 mV, 4 mV, and 5 mV. It successfully detects peak voltages ranging from 1.69 V to 1.92 V, with stabilization achieved within 60 µs, enabling accurate detection of the f (r) signal. The proposed microarchitecture offers a scalable approach to localized thermal monitoring in smart building environments using fully analog circuitry, designed and simulated in Cadence Virtuoso using the TSMC 180 nm technology library.

Micro doi: 10.3390/micro5020027

Authors: Christine C. Gaylarde José Antônio Baptista Neto Estefan M. da Fonseca

The dynamic relationship between microplastics (MPs) in the air and on the Earth’s surface involves both natural and anthropogenic forces. MPs are transported from the ocean to the air by bubble scavenging and sea spray formation and are released from land sources by air movements and human activities. Up to 8.6 megatons of MPs per year have been estimated to be in air above the oceans. They are distributed by wind, water and fomites and returned to the Earth’s surface via rainfall and passive deposition, but can escape to the stratosphere, where they may exist for months. Anthropogenic sprays, such as paints, agrochemicals, personal care and cosmetic products, and domestic and industrial procedures (e.g., air conditioning, vacuuming and washing, waste disposal, manufacture of plastic-containing objects) add directly to the airborne MP load, which is higher in internal than external air. Atmospheric MPs are less researched than those on land and in water, but, in spite of the major problem of a lack of standard methods for determining MP levels, the clothing industry is commonly considered the main contributor to the external air pool, while furnishing fabrics, artificial ventilation devices and the presence and movement of human beings are the main source of indoor MPs. The majority of airborne plastic particles are fibers and fragments; air currents enable them to reach remote environments, potentially traveling thousands of kilometers through the air, before being deposited in various forms of precipitation (rain, snow or “dust”). The increasing preoccupation of the populace and greater attention being paid to industrial ecology may help to reduce the concentration and spread of MPs and nanoparticles (plastic particles of less than 100 nm) from domestic and industrial activities in the future.

Micro doi: 10.3390/micro5020026

Authors: Moses Gu Suin Chae Seonwoo Kim Yubin Kim Shinui Kang Soobin Park Se-Hoon Park Sung-Hoon Choa Hyunjin Nam

Electromagnetic interference (EMI) shielding is critical for maintaining signal integrity in high-speed electronic packaging. However, conventional shielding approaches face limitations in process complexity and spatial efficiency. In this study, an EMI shielding film based on trimodal silver (Ag) ink and low-dielectric polyimide (PI) resin was developed and comprehensively evaluated. The fabricated film exhibited an average shielding effectiveness (SE) of −99.7 dB in the 6–18 GHz frequency range and demonstrated a 50% increase in electrical conductivity after lamination (from 0.752 × 105 S/m to 1.13 × 105 S/m). The horizontal thermal conductivity reached 34.614 W/m·K, which was 3.4 times higher than the vertical value (10.249 W/m·K). Signal integrity simulations showed significant reductions in near-end crosstalk (NEXT, 77.8%) and far-end crosstalk (FEXT, 65%). Moreover, cyclic bending tests confirmed excellent mechanical durability, with a normalized resistance change below 0.6 after 1000 cycles at a bending radius of 4 mm. Notably, the film enabled a 50% reduction in signal line spacing while maintaining signal integrity, even without strict compliance with the 3W Rule. These results demonstrate the potential of the proposed EMI shielding film as a high-performance solution for advanced packaging applications requiring high-frequency operation, thermal management, and mechanical flexibility.

Micro doi: 10.3390/micro5020025

Authors: Oguzhan Panatli Cansu Gurcan Fikret Ari Mehmet Altay Unal Mehmet Yuksekkaya Açelya Yilmazer

Microfluidic devices are tiny tools used to manipulate small volumes of liquids in various fields. However, these devices frequently require additional equipment to control fluid flow, increasing the cost and complexity of the systems and limiting their potential for widespread use in low-resource biomedical applications. Here, we present a cost-effective and simple fabrication method for PMMA microfluidic chips using laser cutting technology, along with a low-cost and open-source peristaltic pump constructed with common hardware. The pump, programmed with an Arduino microcontroller, offers precise flow control in microfluidic devices for small volume applications. The developed application for controlling the peristaltic pump is user-friendly and open source. The microfluidic chip and pump system was tested using Jurkat cells. The cells were cultured for 24 h in conventional cell culture and a microfluidic chip. The LDH assay indicated higher cell viability in the microfluidic chip (111.99 ± 7.79%) compared to conventional culture (100 ± 15.80%). Apoptosis assay indicated 76.1% live cells, 18.7% early apoptosis in microfluidic culture and 99.2% live cells, with 0.5% early apoptosis in conventional culture. The findings from the LDH and apoptosis analyses demonstrated an increase in both cell proliferation and cellular stress in the microfluidic system. Despite the increased stress, the majority of cells maintained membrane integrity and continued to proliferate. In conclusion, the chip fabrication method and the pump offer advantages, including design flexibility and precise flow rate control. This study promises solutions that can be tailored to specific needs for biomedical applications.

Micro doi: 10.3390/micro5020024

Authors: Joshua Z. R. Dantzler Diana Hazel Leyva Amanda L. Borgaro Md Shahjahan Mahmud Alexis Lopez Saqlain Zaman Sabina Arroyo Yirong Lin Alba Jazmin Leyva

Understanding the mechanical properties of three-dimensional (3D)-printed ceramics while keeping the parts intact is crucial for advancing their application in high-performance and biocompatible fields, such as biomedical and aerospace engineering. This study uses non-destructive nanoindentation techniques to investigate the mechanical performance of 3D-printed zirconia across pre-conditioned and sintered states. Vat photopolymerization-based additive manufacturing (AM) was employed to fabricate zirconia samples. The structural and mechanical properties of the printed zirconia samples were explored, focusing on hardness and elastic modulus variations influenced by printing orientation and post-processing conditions. Nanoindentation data, analyzed using the Oliver and Pharr method, provided insights into the elastic and plastic responses of the material, showing the highest hardness and elastic modulus in the 0° print orientation. The microstructural analysis, conducted via scanning electron microscopy (SEM), illustrated notable changes in grain size and porosity, emphasizing the influencing of the printing orientation and thermal treatment on material properties. This research uniquely investigates zirconia’s mechanical evolution at the nanoscale across different processing stages—pre-conditioned and sintered—using nanoindentation. Unlike prior studies, which have focused on bulk mechanical properties post-sintering, this work elucidates how nano-mechanical behavior develops throughout additive manufacturing, bridging critical knowledge gaps in material performance optimization.

Micro doi: 10.3390/micro5020023

Authors: Seonwoo Kim Suin Chae Mirae Seo Yubin Kim Soobin Park Sehoon Park Hyunjin Nam

This study presents the development of a modified polyimide (MPI) with low dielectric properties and low-temperature curing capability for high-frequency flexible printed circuit boards (FPCBs). MPI was cured using dicumyl peroxide (DCP) at 80–140 °C through a radical process optimized via DSC analysis, while Fourier-transform infrared (FT-IR) confirmed the elimination of C=C bonds and the formation of imide structures. The MPI film exhibited low dielectric constants (Dk) of 1.759 at 20 GHz and 1.734 at 28 GHz, with ultra-low dissipation factors (Df) of 0.00165 and 0.00157. High-frequency S-parameter evaluations showed an excellent performance, with S11 of −32.92 dB and S21 of approximately −1 dB. Mechanical reliability tests demonstrated a strong peel strength of 0.8–1.2 kgf/mm (IPC TM-650 2.4.8 standard) and stable electrical resistance during bending to ~6 mm radius, with full recovery after severe deformation. These results highlight MPI’s potential as a high-performance dielectric material for next-generation FPCBs, combining superior electrical performance, mechanical flexibility, and compatibility with low-temperature processing.

Micro doi: 10.3390/micro5020022

Authors: Joon-Koo Kang Kihak Lee Yein Choi Se-Gie Kim Bonghwan Kim

Microneedles (MNs) have emerged as a promising tool for pain-free drug delivery, offering an alternative to traditional syringe-based methods. Among various types of MNs, dissolving microneedles fabricated from hyaluronic acid (HA) have gained attention due to their biocompatibility and ability to deliver drugs with minimal discomfort. However, conventional HA MN fabrication techniques often limit needle lengths to a few hundred micrometers, which is insufficient for deeper drug penetration. This study introduces a novel fabrication method using bidirectional drawing lithography to extend the length of HA-based MNs. By adjusting the viscosity of HA solutions and employing a controlled pulling process, we demonstrate the feasibility of producing MNs with lengths ranging from millimeters to micrometers. An average height of 15 mm and tip diameters of approximately 80 μm were successfully produced. This advancement enhances the potential of HA MNs for transdermal drug delivery and interstitial fluid sampling.

Micro doi: 10.3390/micro5020021

Authors: Yoshiyuki Yamamoto Hiromu Sato

The heat generation characteristics of magnetic nanoparticles (NPs) induced by an alternating magnetic field (AMF) while simultaneously exposed to a DC magnetic field are crucial for the clinical application of magnetic fluid hyperthermia integrated with magnetic particle imaging. In this study, we investigated the dependence of the specific absorption rate (SAR) of magnetite and cobalt (Co) ferrite NP suspensions on a static transverse DC magnetic field under an applied AMF. The results showed that the SAR of Co ferrite NPs remained unaffected by the DC magnetic field, whereas that of magnetite NPs gradually decreased as the DC magnetic field increased. Furthermore, the SAR of magnetite NPs dispersed in high-viscosity solvents was somewhat lower than that of particles dispersed in water, while the SAR of Co ferrite NPs was significantly reduced. These findings can be explained by differences in the Néel relaxation time, which arise from variations in magnetic anisotropy.

Micro doi: 10.3390/micro5020020

Authors: Tamara Tomašegović Sanja Mahović Poljaček Ivona Jurišić Davor Donevski

The objective of this research was to fine-tune the surface properties of printed ink layers by incorporating TiO2 and ZnO nanoparticles into conventional flexographic ink. This modification aimed to improve print quality while simultaneously providing protection against counterfeiting. The presence of nanoparticles in the inks was indirectly detected through FTIR-ATR spectroscopy, which revealed changes in the fingerprint region of the ink spectrum when nanoparticles were added. This alteration enhanced the anti-counterfeiting potential of a produced print. The colorimetric measurements indicated that the addition of nanoparticles did not significantly affect the colorimetric properties of the print, since the maximal calculated ΔEab value was 2.83. However, the nanoparticles notably improved the ink coverage on printed line elements and allowed for the printing of elements without the characteristic outline associated with flexographic printing. The best results in terms of line definition and coverage were achieved with the addition of 2% rutile TiO2 and 1% ZnO to the ink: the measured line segment area covered in ink was 28.5% larger than the same area printed using unmodified ink. This improvement in print quality was attributed to the modified surface free energy (SFE) of the inks, which also influenced the adhesion parameters between the printed layer and the printing substrate. The lowest total SFE was calculated for the ink without added nanoparticles (40.31 mJ/m2), and the highest for the ink with the addition of 2% rutile TiO2 (48.33 mJ/m2). The work of adhesion increased after adding the nanoparticles to the ink, thereby improving the adhesion. The highest work of adhesion (79.36 mJ/m2) was calculated for the ink with 2% rutile TiO2. Interfacial tension was low and close to zero for all printed ink layers, and the lowest value was achieved for the ink without added nanoparticles (1.47 mJ/m2). The findings of this research demonstrated that fine-tuning the properties of flexographic inks using nanoparticles can yield several benefits in terms of optimizing the quality of and providing counterfeit protection for specific printed motifs.

Micro doi: 10.3390/micro5020019

Authors: Refat Al-Shannaq Monzer Daoud Mohammed Farid Md Wasi Ahmad Shaheen A. Al-Muhtaseb Mazhar Ul-Islam Abdullah Al Saidi Imran Zahid

Thermal energy storage offers a viable solution for managing intermediate energy availability challenges. Phase change materials (PCMs) have been extensively studied for their capacity to store thermal energy when available and release it when needed, maintaining a narrow temperature range. However, effective utilization of PCMs requires its proper encapsulation in most applications. In this study, microcapsules containing Rubitherm®(RT) 21 PCM (Tpeak = 21 °C, ΔH = 140 kJ/kg), which is suitable for buildings, were synthesized using a suspension polymerization technique at different operating temperatures (45–75 °C). Two different water-insoluble thermal initiators were evaluated: 2,2-Azobis (2,4-dimethyl valeronitrile) (Azo-65) and benzoyl peroxide (BPO). The prepared microcapsules were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), particle size distribution (PSD), scanning electron microscope (SEM), and optical microscopy (OM). Additionally, the microcapsules were subjected to multiple melting and freezing cycles to assess their thermal reliability and performance stability. DSC results revealed that the microcapsules using BPO exhibited a latent heat of melting comparable to those produced with Azo-65 at an operating temperature of 75 °C. However, the onset crystallization temperature for the BPO-encapsulated PCMs was approximately 2 °C lower than that of the Azo-65-encapsulated PCMs. The greatest latent heat of melting, 107.76 J/g, was exhibited by microcapsules produced at 45 °C, representing a PCM content of 82 wt. %. On the other hand, microcapsules synthesized at 55 °C and 75 °C showed latent heats of 96.02 J/g and 95.66 J/g, respectively. The degree of supercooling for PCM microcapsules was reduced by decreasing the polymerization temperature, with the lowest supercooling observed for microcapsules synthesized at 45 °C. All microcapsules exhibited a monodisperse and narrow PSD of ~10 µm, indicating uniformity in microcapsule size and demonstrating that temperature variations had no significant impact on the particle size distribution. Future research should focus on low-temperature polymerization with extended polymerization times.

Micro doi: 10.3390/micro5020018

Authors: Christine C. Gaylarde Estefan M. da Fonseca

The increasing global demand for food caused by a growing world population has resulted in environmental problems, such as the destruction of ecologically significant biomes and pollution of ecosystems. At the same time, the intensification of crop production in modern agriculture has led to the extensive use of synthetic fertilizers to achieve higher yields. Although chemical fertilizers provide essential nutrients and accelerate crop growth, they also pose significant health and environmental risks, including pollution of groundwater and other bodies of water such as rivers and lakes. Soils that have been destabilized by indiscriminate clearing of vegetation undergo a desertification process that has profound effects on microbial ecological succession, impacting biogeochemical cycling and thus the foundation of the ecosystem. Tropical countries have positive aspects that can be utilized to their advantage, such as warmer climates, leading to increased primary productivity and, as a result, greater biodiversity. As an eco-friendly, cost-effective, and easy-to-apply alternative, biofertilizers have emerged as a solution to this issue. Biofertilizers consist of a diverse group of microorganisms that is able to promote plant growth and enhance soil health, even under challenging abiotic stress conditions. They can include plant growth-promoting rhizobacteria, arbuscular mycorrhizal fungi, and other beneficial microbial consortia. Bioremediators, on the other hand, are microorganisms that can reduce soil and water pollution or otherwise improve impacted environments. So, the use of microbial biotechnology relies on understanding the relationships among microorganisms and their environments, and, inversely, how abiotic factors influence microbial activity. The recent introduction of genetically modified microorganisms into the gamut of biofertilizers and bioremediators requires further studies to assess potential adverse effects in various ecosystems. This article reviews and discusses these two soil correcting/improving processes with the aim of stimulating their use in developing tropical countries.

Micro doi: 10.3390/micro5020017

Authors: Christian Ebere Enyoh Arti Devi Tochukwu Oluwatosin Maduka Lavista Tyagi Sohel Rana Ifunanya Scholastica Akuwudike Qingyue Wang

Microplastics (MPs) and nanoplastics (NPs) have emerged as persistent environmental pollutants, posing significant ecological and human health risks. Their widespread presence in aquatic, terrestrial, and atmospheric ecosystems necessitates effective removal strategies. Traditional removal methods, including filtration, coagulation, and sedimentation, have demonstrated efficacy for larger MPs but struggle with nanoscale plastics. Advanced techniques, such as adsorption, membrane filtration, photocatalysis, and electrochemical methods, have shown promising results, yet challenges remain in scalability, cost-effectiveness, and environmental impact. Emerging approaches, including functionalized magnetic nanoparticles, AI-driven detection, and laser-based remediation, present innovative solutions for tackling MP and NP contamination. This review provides a comprehensive analysis of current and emerging strategies, evaluating their efficiency, limitations, and future prospects. By identifying key research gaps, this study aims to guide advancements in sustainable and scalable microplastic removal technologies, essential for mitigating their environmental and health implications.

Micro doi: 10.3390/micro5020016

Authors: Bani Gandhi Raghava Srinivasa Nallanthighal

This paper presents the design and fabrication of flexible and gel-less electrodes using carboxylic acid-functionalized single-walled carbon nanotubes (SWCNT-COOHs) and polydimethylsiloxane (PDMS) at thirteen different concentrations. The dispersion was attained by magnetic stirring and sonication using isopropyl alcohol (IPA). Physical characterizations like Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Fourier Transform Infrared Spectroscopy (FTIR) were performed. The electrodes were fabricated using molds. The percolation threshold was achieved at 4 wt%. The ECG results were compared with conventional ECG electrodes and 3.5 wt% displayed the best results. Also, after using the electrodes for 5 days, the ECG signals did not degrade and no skin allergies were observed. The fabricated electrodes are suitable for long-term and continuous ECG monitoring, facilitated with the help of an Internet of Things (IoT) tracking system. The data can then be transmitted to the medical expert and loaded onto the cloud server for analysis.

Micro doi: 10.3390/micro5020015

Authors: Hossein Pouri Rakshya Panta Prabhu Bharathan Jiye Fang Jin Zhang

Hydrogen peroxide (H2O2) detection in both liquid and gas phases has garnered significant attention due to its importance in various biological and industrial processes. Monitoring H2O2 levels is essential for understanding its effects on biology, industry, and the environment. Significant advancements in the physical dimensions and performance of biosensors for H2O2 detection have been made, mainly through the integration of fluorescence techniques and nanotechnology. These advancements have resulted in more sensitive, selective, and versatile detection systems, enhancing our ability to monitor H2O2 in both liquid and gas phases effectively. However, limited comprehensive reviews exist on the detection of vaporized H2O2, which is used in disinfection and the production of explosive agents, making its detection vital. This review provides an overview of recent progress in nanostructured fluorescence sensors for H2O2 detection, covering both liquid and gas phases. It examines various fluorescence-based detection methods and focuses on emerging nanomaterials for sensor development. Additionally, it discusses the dual applications of H2O2 detection in biomedical and non-biomedical fields, offering insights into the current state of the field and future directions. Finally, the challenges and perspectives for developing novel nanostructured fluorescence sensors are presented to guide future research in this rapidly evolving area.

Micro doi: 10.3390/micro5010014

Authors: Buta Singh Audrey F. Adcock Simran Dumra Jordan Collins Liju Yang Christopher E. Bunker Haijun Qian Mohammed J. Meziani Ya-Ping Sun

Carbon dots (CDots) are classically defined as small carbon nanoparticles with effective surface passivation, which, in the classical synthesis, has been accomplished by surface organic functionalization. CDot-like nanostructures could also be produced by the thermal carbonization processing of selected organic precursors, in which the non-molecular nanocarbons resulting from the carbonization are embedded in the remaining organic species, which may provide the passivation function for the nanocarbons. In this work, a mixture of oligomeric polyethylenimine and citric acid in the solid state was used for efficient thermal carbonization processing with microwave irradiation under various conditions to produce dot samples with different nanocarbon content. The samples were characterized in terms of their structural and morphological features regarding their similarity or equivalency to those of the classical CDots, along with their significant divergences. Also evaluated were their optical spectroscopic properties and their photoinduced antimicrobial activity against selected bacterial species. The advantages and disadvantages of the thermal carbonization processing method and the resulting dot samples with various features and properties mimicking those of classically synthesized CDots are discussed.

Micro doi: 10.3390/micro5010013

Authors: Esteban Díaz-Torres Ángel Guillén-Cervantes Mauricio Ortega-López

The spray pyrolysis deposition of nanostructured Pb1−xSnxSe alloy films, x = 0.0 to 1.0, from as-prepared Pb1−xSnxSe alloy colloids as the starting solution is reported. The colloidal dispersions were prepared by dissolving selenium in an amine–thiol mixture, reacted with the Sn and Pb precursors in propylene glycol, and subsequently sprayed onto glass substrates at 300 °C. Structural characterization indicated the formation of the alloyed rock-salt cubic phase for 0.0 ≤ x ≤ 0.75, oxidized Pb and Se phases produced during the deposition, and only orthorhombic SnSe for x = 1.0 with Se and SnSe2 as impurities. Nanocrystalline films ranging from 16 to 16.5 nm in size were obtained. The films displayed a shift in their optical structure and a non-monotonic variation in the band gap energy, first a decrease, reaching the minimum at x = 0.30 and a further increase in the Sn content. The decrease in the optical band gap resembles that of a topological insulator behavior. The morphology of the alloyed films confirmed the large nanocrystal formation by self-assembly processes in both the PbSe and SnSe phases and segregated PbSnSe platelets for x ≥ 0.30. Seebeck coefficient revealed that a typical semiconductor behavior dominated by bipolar transport, and p-type conductivity, but only for x = 0.0 n-type conductivity was exhibited. The maximal Seebeck coefficient magnitude behaved similarly to the band gap energy, evidencing the influence of energy band structure and the topological character.

Micro doi: 10.3390/micro5010012

Authors: Marwan Fakhry Olivier Soppera Dominique Berling

Polyvinylidene fluoride (PVDF) is a multifunctional polymer renowned for its unique electrical, mechanical, and piezoelectric properties, making it an attractive candidate for various applications. Although the spin-coating method has been the conventional method for fabricating PVDF thin films, this work is the first to apply the dip-coating technique with humidity control, which is a largely unexplored method in the literature on PVDF thin films. This novel approach offers great prospects for improved control and performance adjustments, as well as expanding the range of film deposition procedures. Here, we examine the phase composition of PVDF thin films; adjust different parameters to optimize the electroactive phases fraction, especially the Beta phase; and examine how relative humidity affects the properties of the film. Moreover, we test the impact of different nanoparticles’ addition on the phases fraction and characteristics of the film. Furthermore, we analyze the topography of the resultant films using several approaches, providing fresh insights into their structural features.

Micro doi: 10.3390/micro5010011

Authors: Vivek P. Chavda Hetvi K. Solanki Dixa A. Vaghela Karishma Prajapati Lalitkumar K. Vora

The cosmetic market is constantly evolving and ever-changing, particularly with the introduction and incorporation of nanotechnology-based processes into cosmetics for the production of unique formulations with both aesthetic and therapeutic benefits. There is no doubt that nanotechnology is an emerging technology for cosmetic formulations. Among the numerous cosmetic items, incorporating nanomaterials has provided a greater scope and is commonly utilized in facial masks, hair products, antiaging creams, sunscreen creams, and lipsticks. In cosmetics, nanosized materials, including lipid crystals, liposomes, lipid NPs, inorganic nanocarriers, polymer nanocarriers, solid lipid nanocarriers (SLNs), nanostructured lipid carriers (NLCs), nanofibers, nanocrystals, and nanoemulsions, have become common ingredients. The implementation of nanotechnology in the formulation of face masks will improve its efficacy. Nanotechnology enhances the penetration of active ingredients used in the preparation of face masks, such as peel-off masks and sheet masks, which results in better effects. The emphasis of this review is mainly on the formulation of cosmetic face masks, in which the impact of nanotechnology has been demonstrated to improve the product performance on the skin.

Micro doi: 10.3390/micro5010010

Authors: Sakshi Koul Luke A. Devecka Mark C. Pierce Maribel Vazquez

Microscale systems have been underexplored in contemporary regenerative therapies developed to treat vision loss. The pairing of in vitro cell systems with optical fluorescent imaging provides unique opportunities to examine the infiltration of donor stem cells needed for successful transplantation therapies. A parallel eye device was developed to provide electric field (EF) stimulation to guide the migration of cells within 3D eye facsimiles synthesized from different ocular biomaterials. Cell infiltration within facsimiles was rapidly resolved using confocal microscopy to eliminate dependence on the cryostat sectioning commonly used for cell study. Moreover, EF stimulated galvanotaxis of donor cells within different depths of eye facsimiles. Optical imaging provided rapid resolution of z-stack images at physiologically appropriate depths below 500 microns. This study demonstrates that paired microscale–optical systems can be developed to elucidate understudied transplantation processes and improve future outcomes in patients.

Micro doi: 10.3390/micro5010009

Authors: Xinyi Zhao Baljit Singh Christine O’Connor Hugh J. Byrne Furong Tian

Escherichia coli (E. coli) and Agrobacterium tumefaciens (A. tumefaciens) are bacterial species commonly found in the environment, and they can do much harm to humans, animals and plants. As a result, it is necessary to find an accurate, rapid, simple method to detect the concentrations of them, and polymerase chain reaction (PCR) is one of the most suitable candidates. In this study, a gold nanoparticles (GNPs) enhanced polymerase chain reaction was developed, to simultaneously target the specific genes, 16S rDNA of E. coli and Tms1 of A. tumefaciens. PCR amplification times (CT values) of E. coli and A. tumefaciens were seen to be lowered significantly by the incorporation of GNPs. The fluorescence intensities in quantitative PCR amplifications of both E. coli and A. tumefaciens reached the maximum after around 40 cycles, and the PCR yield (maximum fluorescence intensity) was proportional to the maximum absorbance at 495 nm in the corresponding UV-vis spectra. GNPs were found to enhance the PCR yield of both E. coli and A. tumefaciens, and smaller sized GNPs (average 13 nm) showed a better enhancement effect compared to larger sized GNPs (average 30 nm). Conventional PCR showed that both E. coli and A. tumefaciens could be detected together with limit of detection of 10 CFU/mL for each bacterium, using GNPs of 13 nm. The results of this study could lead to improvement of multiplex PCR that can detect different bacteria species simultaneously.

Micro doi: 10.3390/micro5010008

Authors: Dieter Vollath

Any application of nanoparticles is influenced by the unavoidable tendency of these particles to agglomerate. As a result, one obtains a more or less broad distribution of agglomerate sizes. This may influence the properties significantly. Looking at agglomeration processes, one has to distinguish two different phenomena: the generally discussed problem, where each particle has the chance to combine with any other particle, or the case, where an agglomeration is possible only with direct neighbors. The latter case, which is the subject of this study, is observed when the particles are stored in a box. In contrast to conventional analyses, the calculations for this paper are based on Markov chain Monte Carlo calculations. This paper describes the formation and development of these agglomerates and the resulting distributions. For an improved depiction of the results, a new quantity derived from entropy, the ‘integral entropy’, was developed. This quantity allows efficient visualization of the development of the agglomerates as a function of the iteration steps resulting from these calculations; additionally, applying the integral reduces the statistical scattering of the results. Furthermore, different mechanisms and interaction parameters were assumed and compared. The results were analyzed to show progress that depends on the number of iteration steps. An important result of these calculations is the distribution of agglomerate sizes and the number of agglomerates as a function of the number of iterations. The calculations are based on different assumptions on the agglomeration and arrangements of the particles.

Micro doi: 10.3390/micro5010007

Authors: Santu Guin Debjyoti Chowdhury Madhurima Chattopadhyay

In recent years, various types of sensors have been developed at both millimeter (mm) and micrometer (µm) scales for numerous biomedical applications. Each design has its own advantages and limitations. This study compares the electrical characteristics and sensitivity of millimeter- and micrometer-scale sensors, emphasizing the superior performance of millimeter-scale designs for detecting type-2 diabetes. Elevated glucose levels in type-2 diabetes alter the complex permittivity of red blood cells (RBCs), affecting their rheological and electrical properties, such as viscosity, volume, relative permittivity, dielectric loss, and AC conductivity. These alterations may manifest as a unique bio-impedance signature, offering a diagnostic topology for diabetes. In view of this, various concentrations (ranging from 10% to 100%) of 400 µL of normal and diabetic RBCs suspended in phosphate-buffered saline (PBS) solution are examined to record the changes in bio-impedance signatures across a spectrum of frequencies, ranging from 1 MHz to 10 MHz. In this study, simulations are performed using the finite element method (FEM) with COMSOL Multiphysics® to analyze the electrical behavior of the sensors at both millimeter (mm) and micrometer (µm) scales. These simulations provide valuable insights into the performance parameters of the sensors, aiding in the selection of the most effective design by using this topology.

Micro doi: 10.3390/micro5010006

Authors: Harshad S. Kapare Sunil Kanadje Prabhanjan Giram Aditi Patil Ritesh P. Bhole

Quercetin, a flavonoid, has well-proven cytotoxicity potential, but its therapeutic efficacy is hampered by hydrophobicity, stability issues, and lower bioavailability. The present research aims to address these issues and formulation barriers by formulating a quercetin-loaded micellar nanogel. Quercetin was encapsulated in PF 68 micelles to enhance its solubility, loading, and stability to better its therapeutic potential. The nanogel was further characterized regarding for pH, spreadability, and in vitro cytotoxicity against human breast cancer cells (MCF-7). The resulting micelles exhibited a particle size of 180.26 ± 2.4 nm, surface charge of −13.5 mV, entrapment efficiency of 78.4 ± 1.2%, and in vitro release of 96.11 ± 0.75% up to 8 h. This in vitro cytotoxicity study on MCF-7 cell lines reveals the improved TGI and GI 50 values of micellar nanogel formulation compared to quercetin. The overall study results demonstrated that the developed micellar nanogel system might serve as a promising nanocarrier to enhance the cytotoxic potential of quercetin in cancer therapy.

Micro doi: 10.3390/micro5010005

Authors: Kathryn A. Whitehead Mark Brown Lucia Caballero Stephen Lynch Michele Edge Claire Hill Joanna Verran Norman S. Allen

This work determined the resistance of paint formulations containing TiO2 particles to fungal growth. Siloxane, acrylic and silicone paints were placed outdoors, and the fungal species growing thereon were recorded after 3, 6 and 9 months. In addition, three paint types containing TiO2 with/without biocide were inoculated with fungal spores and irradiated using UV. Acrylic paints were also doped with different metals and were inoculated and incubated under fluorescent light. Following outdoor incubation, the silicone paint was the least colonised by different fungal species. The species most recovered from the surfaces were Aspergillus spp. and Penicillium spp. Following UV irradiation on different paints containing biocide and/or a photocatalyst, no fungal growth was demonstrated on some of the paint combinations. When the paint samples were doped with different metals and incubated using light, the sample most efficient at preventing fungal growth contained lanthanum (0.004%). The paint samples containing praseodymium (light:1.72) facilitated the densest fungal colonies. Most of the surfaces demonstrated heterogeneous coverage by the fungi. The most clustered fungal colonisation was on surfaces incubated in the light. This work demonstrated that fungal colonisation on paints changed over time and that the antimicrobial efficacy of TiO2 was affected by the chemical composition, biocide and doping of the paint.

Micro doi: 10.3390/micro5010004

Authors: Dinesh Bhalothia Tien-Fu Li Amisha Beniwal Ashima Bagaria Tsan-Yao Chen

The catalytic conversion of carbon dioxide (CO2) into carbon monoxide (CO) via the reverse water–gas shift (RWGS) reaction offers a promising pathway toward a sustainable carbon cycle. However, the competing Sabatier reaction presents a significant challenge, underscoring the need for highly efficient catalysts. In this study, we developed a novel catalyst comprising cobalt-oxide-supported nickel-hydroxide nanoparticles (denoted as Co@Ni). This catalyst achieved a remarkable CO production yield of ~5144 μmol g−1 at 573 K, with a CO selectivity of 77%. These values represent 30% and 70% improvements over carbon-supported Ni(OH)2 (Ni-AC) and CoO (Co-AC) nanoparticles, respectively. Comprehensive physical characterizations and electrochemical analyses reveal that the exceptional CO yield of the Co@Ni catalyst stems from the synergistic electronic interactions between adjacent active sites. Specifically, cobalt-oxide domains act as electron donors to Ni sites, facilitating efficient H2 splitting. Additionally, the oxygen vacancies in cobalt oxide enhance CO2 adsorption and promote subsequent dissociation. These findings provide critical insights into the design of highly efficient and selective catalysts for the RWGS reaction, paving the way for advancements in sustainable carbon utilization technologies.

Micro doi: 10.3390/micro5010003

Authors: Haorong Li Jinfeng Li

This work addresses a critical challenge in microscale computational electromagnetics for liquid crystal-based reconfigurable components: the inadequate capability of current software to accurately identify and simulate higher-order modes (HoMs) in complex electromagnetic structures. Specifically, commercial simulators often fail to capture modes such as Transverse Electric (TE11) beyond the fundamental transverse electromagnetic (TEM) mode in coaxial liquid crystal phase shifters operating in the terahertz (THz) regime, leading to inaccurate performance predictions and suboptimal designs for telecommunication engineering applications. To address this limitation, we propose a novel diagnostic methodology incorporating three lossless assumptions to enhance the identification and analysis of pseudo-HoMs in full-wave simulators. Our approach theoretically eliminates losses associated with metallic conductivity, dielectric dissipation, and reflection effects, enabling precise assessment of frequency-dependent HoM power propagation alongside the primary TEM mode. We validate the methodology by applying it to a coaxially filled liquid crystal variable phase shifter device structure, underscoring its effectiveness in advancing the design and characterization of THz devices. This work provides valuable insights for researchers and engineers utilizing closed-source commercial simulators in micro- and nano-electromagnetic device development. The findings are particularly relevant for microscale engineering applications, including millimeter-wave (mmW), sub-mmW, and THz systems, with potential impacts on next-generation communication technologies.