Micro

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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 (D_k) of 1.759 at 20 GHz and 1.734 at 28 GHz, with ultra-low dissipation factors (D_f) 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. Full article

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. Full article

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. Full article

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 ΔE_ab 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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

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. Full article

The spray pyrolysis deposition of nanostructured Pb_1−xSn_xSe alloy films, x = 0.0 to 1.0, from as-prepared Pb_1−xSn_xSe 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. Full article