Micro, Volume 5, Issue 4 (December 2025) – 17 articles

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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(Bi_0.5Na_0.5)TiO₃–0.05BaTiO₃)–x(0.5Ba_0.7Ca_0.3TiO₃–0.5BaTi_0.8Zr_0.2O₃), 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 T_F–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 (W_rec) 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. Full article

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. Full article

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@$C_{2v}\left(9\right)$-C₈₂ and Dy@$C_s\left(6\right)$-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@$C_{2v}\left(9\right)$-C₈₂ species is found as lower in the potential energy by 1.77 kcal/mol compared to the Dy@$C_s\left(6\right)$-C₈₂ isomer. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article