Search Results (2,463)

The ability to assess molecular binding kinetics in real time is critical for advancing our understanding of molecular interactions in biochemical and biotechnological systems. This work presents a novel optical tweezer (OT)-based method to monitor molecular affinity in real time, focusing on the high-affinity streptavidin–biotin system as a model. Transparent poly(methyl methacrylate) (PMMA) microparticles functionalized with streptavidin were trapped before, during, and after binding with biotinylated bovine serum albumin (biotin–BSA), enabling the analysis of forward-scattered signals to detect nanoscale changes in particle size. By applying the Power Spectral Density method, the friction coefficient of individual particles was calculated, allowing for real-time tracking of binding dynamics and the estimation of the association rate constant ($k_{\mathrm{on}}\approx {10}^6{\mathrm{M}}^{-1}{\mathrm{s}}^{-1}$). These results are consistent with literature values and demonstrate the potential of this OT-based approach for non-invasive, label-free detection of molecular interactions. Compared to existing techniques, such as atomic force microscopy and cantilever-based sensors, this method offers significant advantages, including real-time monitoring, adaptability to different bioaffinity systems, and compatibility with miniaturized setups. This work establishes a foundation for using OT-based tools to monitor high-affinity molecular interactions in real time. While demonstrated here using biotinylated BSA as a model ligand, future studies will explore the method’s applicability to smaller ligands and more subtle surface modifications. Full article

Silica particles are promising multifunctional drug delivery platforms; however, when in contact with blood or other biological fluids, proteins rapidly adsorb to their surface, forming the protein corona that modulates their biological interactions. In this study, silica microparticles were coated with lipid bilayers using two approaches: the lipid film hydration method and the on-particle solvent-assisted lipid coating (OPSALC) technique. We investigated how phospholipids with varying charges (zwitterionic, anionic, and cationic) and membrane phase influence coating formation and protein corona adsorption. The coating coverage and aggregation were characterized by fluorescence microscopy. The lipid film hydration method enabled coating with a broad range of lipids, but was highly dependent on the membrane phase and electrostatic interactions between lipid head group and particle surface. Pure anionic coatings were not achievable with this method; however, when combining the OPSALC method with a pre-silanization step, fully anionic coatings of silica microparticles were successfully obtained. Assessment by SDS-PAGE revealed differences in protein corona profiles modulated by the lipid compositions on the particles’ coatings. Overall, this study highlights the dependence of coating formation and protein corona composition on the phospholipid coatings’ properties. Full article

Polymeric microspheres synthesized via Pickering emulsion polymerization offer structural tunability, making them attractive platforms for dye adsorption. This study investigates the adsorption behavior of methylene blue onto two classes of polymeric microspheres—poly(methacrylic acid) crosslinked with ethylene glycol dimethacrylate (PM), containing both micro- and nanopores, and poly(methacrylic acid) crosslinked with divinylbenzene (PD), containing only nanopores. The adsorption kinetics were modeled using a dual-process approach that distinguishes between diffusion-controlled transport and surface-controlled kinetic adsorption. We quantified the relative contributions of these mechanisms and correlated them with particle architecture. In the PM particles, diffusion plays a significant role in smaller particles with larger macropores, enabling methylene blue to penetrate the interior. As the particle size increased and macroporosity decreased, adsorption becomes increasingly dominated by surface kinetics. In contrast, PD particles —which lack macropores—showed the opposite trend: smaller particles were primarily governed by fast surface adsorption, while in larger particles, diffusion through nanopores became increasingly relevant. Correlation analysis between adsorption rate constants and structural parameters such as particle diameter and pore sizes revealed strong, opposing trends. In PD particles, a near-perfect inverse correlation was observed between the diffusion and kinetic components, indicating competitive suppression, where the dominance of one mechanism limited the contribution of the other. These results demonstrated that internal pore architecture played a central role in controlling the adsorption mechanism. Tuning particle size and porosity allowed deliberate control over the balance between diffusion and surface kinetics, enabling the rational design of microparticle adsorbents with tailored uptake behavior for water purification and dye removal applications. Full article

This study aimed to slow down starch digestion by encapsulating the starch granule within a firm zein shell via solvent-exchange-induced zein deposition. The zein shell adhered tightly to the granule surface and the shell thickness increased with increasing zein concentration. The average shell thickness of microparticles produced with zein (1%, 2%, and 3% w/v) was 0.54 μm, 0.97 μm, and 1.63 μm, respectively. Thicker zein shells acted as a mechanical barrier limiting heat transfer and water penetration, thus significantly affecting the starch digestibility. The in vitro simulated digestion experiment indicated that CS-3% zein microparticles exhibited an approximately 19-fold higher resistant starch (RS) content compared with native corn starch. These findings demonstrated the potential of the zein acting as a shell material in developing delivery system for controlled starch digestion. Additionally, this study validated antisolvent precipitation as an effective method to construct hydrophilic core/hydrophobic shell delivery systems to encapsulate unstable and hygroscopic compounds. Full article

Ensuring efficient nutrient delivery and waste removal within the interior of three-dimensional (3D) cultures remains a major challenge in tissue engineering. Here, we demonstrate a proof-of-concept methodology that creates internally distributed driving sources to enhance diffusion and perfusion within 3D constructs. Iron microparticles or iron-containing microtubes were incorporated into collagen gels used for the 3D culture of dermal or cardiac fibroblasts, and cyclic dynamic magnetic fields were applied to the constructs. Oscillatory motion of the iron particles enhanced diffusion within the gels, as evidenced by increases in the fast diffusion coefficient of more than threefold and the slow diffusion coefficient of more than tenfold under conditions suitable for cell culture. In cardiac fibroblast cultures, this enhancement significantly increased proliferation by approximately twofold and reduced cytotoxicity by half compared with controls. In contrast, no significant effects were observed in dermal fibroblast cultures. Cyclic compression of microtubes within the collagen gels induced by dynamic magnetic fields primarily resulted in cellular morphological changes, including a reduction in cell area to approximately 0.8-fold of the control values, increased cell polarization with the cellular aspect ratio rising from 1.4 to 1.9, and preferred cell orientations either parallel or perpendicular to the microtube axis. Together, these results suggest that this methodology has the potential to be developed as an effective strategy for improving diffusivity in 3D metabolic environments and for promoting angiogenesis in hydrogel-based cultures. Full article

The field of extracellular vesicle (EV) research offers a compelling example of a biological concept refined through continuous methodological innovation. This review traces the historical trajectory of the discipline chronologically, beginning with early observations in haemostasis, from Malpighi’s descriptions of blood clots and Chargaff and West’s identification of a procoagulant sedimentable plasma fraction, to Wolf’s “platelet dust,” Crawford’s microparticles characterised by electron microscopy, and the seminal work by Stahl and Johnstone demonstrating regulated vesicle biogenesis during reticulocyte maturation via multivesicular bodies. We highlight a pivotal conceptual shift, from viewing EVs as cellular debris to recognising them as regulated “communicasomes,” catalysed by Raposo’s discovery of antigen-presenting exosomes and subsequent evidence for EV-mediated transfer of functional receptors and nucleic acids, including the influential and sometimes debated model proposed by Ratajczak. By integrating findings from matrix vesicles, plant-derived vesicles, and diverse tissue contexts, we frame EV release as an evolutionarily conserved process with profound implications for immunity, regeneration, oncology, and cardiovascular pathology. A second central aim of this review is practical and methodological. We map how the expansion of biological claims has driven urgent standardisation efforts, notably through the establishment of the International Society for Extracellular Vesicles (ISEV) and the successive MISEV guidelines (2014, 2018, 2023). These are complemented by community resources such as EV-TRACK, MIFlowCyt-EV, and the databases ExoCarta and Vesiclepedia. We summarise core experimental choices across isolation and characterisation techniques, including ultracentrifugation, size exclusion chromatography, density gradients, flow cytometry, nanoparticle tracking analysis, and electron microscopy, while outlining persistent bottlenecks in purity, standardised nomenclature, and experimental reproducibility. Finally, we provide concise biographical sketches of key contributors and an overview of major EV-focused journals and ISEV meetings that anchor consensus-building and the translation of fundamental knowledge into clinical and industrial applications. Full article

This study aimed to manufacture and characterize highly porous dressings based on gellan gum (GG) and sodium alginate (Alg) hydrogels modified with zinc oxide (ZnO) and bacitracin (BAC) intended for infected and exuding wounds. ZnO nanoparticles (ZnO(n)) were 26 ± 4 nm in size according to atomic force microscopy (AFM), while the size of the microparticles (ZnO(m)) was 1.02 ± 0.01 µm according to laser diffraction measurements. Their relative surface areas were 39.16 m²/g and 4.56 m²/g, respectively. Microbiological studies showed that ZnO(n) exhibited antibacterial activity in contact with the Gram+ Staphylococcus aureus; thus, they were selected for embedding in a hydrogel matrix. Four types of composite hydrogel samples were manufactured: GG/Alg, GG/Alg+ZnO, GG/Alg+BAC, and GG/Alg+ZnO+BAC, which were subjected to freeze drying. The water absorption of all materials exceeded 4000%, showing excellent liquid absorbability. Burst release of BAC was found at a level of 90% in the first 2 h. In vitro cytotoxicity studies on L929 fibroblasts did not show a toxic effect of extracts from the GG/Alg and GG/Alg+BAC samples, contrary to samples supplemented with ZnO(n). In microbiological studies, the enhanced antibacterial effect of ZnO(n) and BAC was observed in contact with Staphylococcus aureus and Staphylococcus epidermidis strains. Therefore, GG/Alg+BAC+ZnO is the most promising dressing system for the treatment of infected and exuding wounds. Full article

Acoustofluidics has emerged as a transformative technology for contact-free manipulation of microparticles and fluids in microscale systems. Although bulk acoustic waves (BAWs) are known to displace inhomogeneous fluids through acoustic radiation force acting at fluid interfaces, the capability of surface acoustic waves (SAWs) to produce analogous relocation phenomena remains largely unexplored. This study addresses a critical gap in acoustofluidic theory by presenting the first comprehensive finite element method investigation of SAW-driven motion of inhomogeneous fluid confined within microchannels of widths equal to one full or one-half SAW wavelength. Unlike BAW-based system that generate uniform pressure fields across channel heights, SAW devices exhibit inherently nonuniform vertical pressure distributions and intense near-boundary streaming—features that fundamentally alter fluid relocation dynamics. Our simulations demonstrate that despite high-frequency operation (6.65 MHz) and strong ARF, standing SAW fields fail to achieve stable fluid relocation in both initially stable and unstable configurations due to vertical pressure stratification and rapid floor-level streaming. Nevertheless, these same characteristics generate vigorous transverse folding flows that enable exceptionally rapid homogenization, offering a distinct acoustofluidic mechanism for on-chip mixing. These findings not only elucidate fundamental physical differences between BAW and SAW actuation in multiphase microfluidic systems but also establish design principles for SAW-induced microfluidic mixers. The results provide crucial theoretical guidance for device optimization where rapid homogenization is desired over stable stratification. Full article

Highly pathogenic avian influenza A/H5N1 remains a persistent threat to public health and poultry production. H5N1 antigens are typically poorly immunogenic and require effective adjuvants for antigen dose-sparing. Here, we evaluated chitosan microparticles (CSMs) and nanoparticles (CSNs) as polymeric nano-adjuvants for an H5N1 influenza vaccine, focusing on the roles of antigen dose and particle size. A purified hemagglutinin antigen was adsorbed onto chitosan particles at doses ranging from 0.15 to 5.0 µg. Both CSNs and CSMs showed consistently high loading efficiency (97–99%). BALB/c mice were immunized intramuscularly in a prime–boost schedule. Chitosan nanoparticles significantly enhanced IgG and hemagglutination inhibition (HI) titers at low antigen doses compared with aluminum hydroxide and antigen-only controls (p < 0.05). Immune responses reached saturation at a 1.5 µg dose of antigen for chitosan nanoparticles and 3.0 µg for chitosan microparticles. IgG subtype analysis suggested a balanced IgG1/IgG2a profile. Collectively, these findings support chitosan-based polymeric nanoparticles as promising adjuvants enabling dose-sparing H5N1 vaccination. Full article

Water purification and treatment methods are becoming increasingly complex due to the use of new additives, solvents, pesticides, dyes, and other emerging pollutants in industry, agriculture, and households. Consequently, the search for new water treatment techniques and materials that can help reduce this environmental impact has become a major focus in the field of green chemistry. In this work, the photocatalytic degradation capacity of composites containing TiO₂ nanoparticles (TNPs) for the removal of organic pollutants in water was studied. The TNPs were immobilized in bio-based hydrogel microparticles, which were prepared using microfluidic techniques. The composition of the dispersed phase was optimized with a lab-on-a-chip device, resulting in composite microparticles with a narrow size distribution. UV–visible spectroscopy results indicated that increasing the concentration of TNPs in the hydrogel microparticles enhanced the photodegradation performance of the new composite. Remarkably, it was able to efficiently degrade nearly 90% of reference dyes after four adsorption–desorption cycles. Full article

The use of chemical fertilizers has led to significant environmental pollution. An alternative to these fertilizers is the use of natural compounds, such as phytohormones, which promote germination and crop development. However, environmental factors can affect natural compounds, reducing their effectiveness. Therefore, increasing their stability without decreasing their activity to improve crop quality is essential. This study produced and characterized chitosan and sodium tripolyphosphate (TPP) nano-microparticles (NMP) loaded with Bacillus subtilis extract and evaluated their impact on tomato seed germination. We employed two experimental designs (Box–Behnken and Box–Hunter–Hunter) to determine the optimal production conditions and characterized the NMP using DLS, SEM, and FTIR. The optimal treatment consisted of 8 min of homogenization, followed by 8 min of ultrasound at a 70% amplitude, resulting in a particle size of 330.7 nm, a polydispersity index of 0.25, a zeta potential of 34.3 mV, and an encapsulation efficiency of 68.8%. The NMP loaded with bacterial extract was applied to tomato seeds as a 50% dilution pretreatment. NMP achieved the best results, with a 72% germination rate (1.6 seeds per day) and an average germination time of 3.8 days. It is concluded that the experimental designs helped improve particle properties and that the chitosan and TPP coating enhances the stability and activity of the bacterial extract, potentially benefiting agronomic applications. Full article

The aim of our study was to determine the importance of different pitcher syndrome characters (size of the trap, the presence of inner microscopic surface coverage, physical properties of the pitcher fluid) for insect trapping efficiency using artificial, “biomimetic” pitchers. We performed trapping experiments with Drosophila melanogaster flies, applied cryo scanning electron microscopy for characterization of the topography of surface coatings and visualization of their contaminability effects on insect attachment organs, and conducted contact angle measurements with different liquids used in experiments. The type of the liquid used as the pitcher fluid had the most important impact on the trapping efficiency; surfactant-containing liquids exhibiting strong wetting properties provided a high number of trapped flies. The diameter of the trap rather than its height influenced insect trapping efficiency; apparently, because wider traps provide a larger space for more insects to get into a trap, they captured more flies in comparison to narrower traps. The presence of both the calcium carbonate and kaolin coatings mimicking the epicuticular wax coverage inside pitchers in many Nepenthes species additionally contributed to the trapping success due to a reduction of contact between insect feet and the trap surface and to contamination of flies’ attachment organs by detached microparticles. Full article

Bone regeneration focuses on the creation of functional tissue to repair bone defects. Creating a biodegradable scaffold hydrogel that combines a hemostatic agent with bioactive ceramics can afford the biological and mechanical benefits of both components. In the present study, we developed an injectable gelatin–alginate dual-composite hydrogel, loaded with two functional fillers: hydroxyapatite (HA) and the hemostatic agent montmorillonite (MMT). HA (microparticles and nanoparticles) was incorporated at concentrations of 10–30 mg/mL, with and without MMT at 20 mg/mL. The effects of functional fillers and their concentration on the microstructure and resulting physical and mechanical properties were studied, and a qualitative model summarising these effects was developed. All formulations exhibited clinically appropriate gelation times (5–29 s). n-HA significantly prolonged gelation time, reaching 29 ± 3 s at 30 mg/mL, while MMT reduced gelation time at all concentrations. The tensile strength of the unloaded hydrogel reached 20 kPa and increased to 57 kPa with 30 mg/mL of n-HA. The tensile strength even increased further with the addition of MMT (77 kPa). The results indicate that the combination of HA and MMT produced dual micro-composite hydrogels with moderate reinforcement, whereas the combination of n-HA and MMT generated dual nano–micro composites with combined reinforcing effects. The latter exhibited the highest strength and sealing ability while maintaining clinically relevant gelation times and controlled swelling behaviour. In conclusion, the combination of MMT with n-HA or HA enables the creation of functional hydrogels with controlled properties, tailored to specific applications in bone regeneration. Full article

The present study investigated the impact of microplastics, specifically polystyrene microparticles (PS-MP), on the hypothalamic-pituitary-gonadal (HPG) neurohormonal axis, which regulates reproductive functions in animals and humans. The primary objective was to examine the effects of PS-MP on the expression of key genes and hormone concentrations within the gonadotropic system of sheep. Two doses of PS-MP—the lower dose (LD; 0.015 mg/kg) and the higher dose (HD; 0.15 mg/kg)—were administered intravenously every three days over two estrous cycles (34 days). Both doses significantly decreased the relative abundance of gonadotropin-releasing hormone (GnRH) transcripts in the mediobasal hypothalamus (MBH), whereas only the HD reduced GnRH mRNA levels in the preoptic area (POA). These transcript-level changes were not accompanied by detectable alterations in GnRH protein concentration. In the MBH, the expression of kisspeptin (KISS-1) and neurokinin B (NKB) genes decreased following exposure to the HD, whereas in the POA, significant decrease in expression were observed only after the LD administration. Changes in prodynorphin (PDYN) gene expression were confined to the MBH and were dose-dependent: the LD increased transcript levels, whereas the HD caused a decrease. The HD of PS-MP also significantly downregulated GnRH receptor (GnRHR) expression in the anterior pituitary (AP). Both PS-MP doses resulted in marked reductions in luteinizing hormone beta (LHβ) and follicle-stimulating hormone beta (FSHβ) subunit gene expression in the AP, without significant changes in hormone protein concentrations. Exposure to PS-MP reduced plasma LH and FSH concentrations: the lower dose reduced both hormones, while the higher dose significantly reduced mainly FSH, showing statistical differences between doses. To summarize, the present study demonstrates that PS-MP exerts a modulatory effect on the secretory activity of the central reproductive system in sheep, at both the hypothalamic and pituitary levels. Consequently, PS-MP has the potential to induce significant disruptions to the reproductive processes of large farm animals. Full article

Chitosan (CH) is a natural biopolymer obtained from the deacetylation process of chitin found in the exoskeleton of crustaceans. Recently, CH has been used as a multifunctional molecule in farm animal health, production, and reproduction. CH has an exceptional chemical structure and physicochemical properties that confer valuable properties, such as biocompatibility, biodegradability, antimicrobial and antioxidant activities, immune modulation, mucoadhesion, and controlled release capabilities. These properties enable CH to be formulated in various forms, including raw CH, chitosan oligosaccharides (COSs), microparticles, nanoparticles (NPs), solutions, gels, and films, thereby expanding its applicability for improving fertility and enhancing reproductive performance in farm animals. Several reports have described various applications of CH and CH-based materials in animal reproduction, including dietary supplementation, sperm preservation, in vitro embryo production (IVEP), treatment of uterine infections such as metritis/endometritis, and integration into synchronization protocols as a hormone delivery system. Therefore, this review outlines the potential applications of CH and CH-based materials to improve reproductive performance in farm animals through both direct and indirect mechanisms. Full article