Search Results (120)

Bone regeneration in critical-size defects requires biomaterials that provide both structural support and appropriate osteoinductive cues. Natural nacre contains an organic matrix rich in acidic macromolecules with reported osteogenic activity; however, its in vivo regenerative potential remains insufficiently explored. This study evaluated the bone regenerative capacity of nacre-derived materials alone and combined with oxidized porous silicon microparticles (pSi-MP), a bioactive material known to release silicic acid and support mineralized tissue formation. Critical-size defects were created in four caudal vertebrae of Wistar rats and filled with nacre, pSi-MP, a nacre–pSi composite, or left empty. After 60 days, bone formation was assessed using micro-computed tomography and non-decalcified histology. Empty defects failed to regenerate, whereas nacre and pSi-MP individually promoted partial mineralized tissue deposition. The nacre–pSi composite produced the most extensive repair, showing near-complete defect bridging, higher bone mineral density, and seamless integration of particles within newly formed bone. No inflammation or adverse reactions were observed, and osteoid deposition occurred directly on material surfaces. These findings demonstrate that nacre-derived materials exert intrinsic osteogenic effects in vivo and that combining nacre with porous silicon yields a synergistic response that significantly enhances bone regeneration. The composite represents a promising candidate for future bone repair strategies. Full article

Owing to their high strength characteristics, chemical stability, and piezoelectric activity, vinylidene fluoride (VDF) copolymers have become promising materials for creating implants to replace bone tissue defects. However, a significant drawback of these materials is the biological inertness of their surface, which leads to unsatisfactory integration with the patient’s bone tissue. In this study, we propose a single-step approach for immobilizing hydroxyapatite (HAp) on the surface of porous implants made of vinylidene fluoride and tetrafluoroethylene copolymer (P(VDF-TeFE)). This method consists of treating the surface of the product with a mixture of solvents while simultaneously capturing HAp microparticles. Using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), it was shown that the proposed method preserves the morphology of model implants (pore diameter and printed line thickness) and allows HAp to cover up to 63 ± 14% of their surface, reaching concentrations of calcium and phosphorus up to 6.0 ± 1.3 and 3.6 ± 0.7 at. %, respectively, imparting superhydrophilic properties to them. Optical profilometry revealed that the surface roughness of samples increased by more than seven times as a result of HAp immobilization. X-ray diffraction analysis (XRD) confirmed that the piezoelectric phase of P(VDF-TeFE) is preserved after treatment, as are the compressive strength characteristics of the samples. Hydroxyapatite immobilization significantly improved the adhesion and osteogenic differentiation of multipotent stem cells cultured with P(VDF-TeFE)-based samples. Thus, the proposed method can significantly enhance the biological activity of implants based on the piezoelectric VDF copolymer. Full article

Polyelectrolyte microspheres based on a polymer containing sulfonate groups are considered promising drug delivery systems for encapsulating drugs and ensuring their prolonged release. In this study, gel microparticles based on various sulfonate-containing polymers were formed, and their potential as drug delivery systems was evaluated, particularly for the controlled administration of the cytotoxic anthracycline antibiotic doxorubicin and the antifungal drug fuchsine. An undeniable advantage of such gel microspheres is the presence in their structure of sulfonate groups localized both in the surface layer and in the volume. The main monomers used were styrene-4-sulfonic acid sodium salt and 3-sulfopropyl methacrylate potassium salt; spherical, porous microparticles were obtained via free-radical reverse suspension polymerization. Microsphere properties (size, porosity, pore structure, electrical surface properties, and swelling) were tailored by changing the nature of the sulfonate, using a comonomer (vinyl acetate or ethyl acrylate), adding a co-solvent, or modulating the crosslinker composition, which influenced drug loading efficiency (doxorubicin, fuchsine). The gel-like structure of the microspheres was confirmed, and the sulfonate groups were found to be distributed throughout both the surface layer and the internal volume of the microspheres. A comparison was also made with non-porous polymer particles containing sulfonate groups. The sorption capacity of the gel microspheres for doxorubicin was 2.2 mmol/g, significantly higher than the 0.4 mmol/g observed for the non-porous reference particles. The obtained values of doxorubicin sorption on gel microspheres are over 60 times higher than the values reported in the literature. Full article

A vacuum-arc pulsed plasma accelerator (APPA) operating at a discharge current of 750 A and a pulse duration of 110 μs with a repetition rate of 5 Hz was employed to deposit thin films and coatings under low- and medium-vacuum conditions. The aim of this study was to obtain metal coatings suitable for potential applications in the energy and chemical industries. SEM, AFM, and XRD techniques were used to investigate the structure and morphology of coatings formed on metallic and insulating substrates under the following conditions: residual pressure of 10⁻²–10⁻⁴ mbar and deposition times of 10–30 min. Under medium-vacuum conditions, thin and non-uniform metallic films with thicknesses ranging from 0.4 to 1.9 μm were deposited on metal substrates. The morphology of thick films deposited under low-vacuum conditions consisted of spherical metal particles of various sizes (0.1–1 μm), containing up to 30% carbon and 28% oxygen. On silicon substrates, spherical microparticles up to 4 μm in diameter with thin shells approximately 0.3 μm thick were formed. One possible mechanism for microsphere formation—the desorption of residual gases by the coating material—is discussed. The potential of the APPA method for producing metal shells, relevant to powder manufacturing due to the high energy density of the process and the intrinsic purity of vacuum technologies, is also considered. Porous coatings obtained using the APPA technique may be applicable in the fabrication of energy-related materials, such as battery anodes. Full article

Fungal infections caused by Fusarium solani demand sustainable alternatives to conventional fungicides and free nanoparticles, which often show poor stability and rapid release. This study developed zinc-crosslinked alginate microparticles containing silver (AgNPs), zinc oxide (ZnONPs), or both to improve nanoparticle stability, sustain release, and enhance antifungal efficacy. Microparticles were produced by ionic gelation and characterized by FTIR, microscopy, swelling analysis, encapsulation efficiency, and kinetic modeling. AgNPs weakened hydrogen bonding within alginate, yielding rough, porous structures, whereas ZnONPs strengthened COO⁻–Zn²⁺ interactions, forming smoother surfaces with smaller pores; co-loaded particles combined both characteristics. Encapsulation efficiencies were 77.9% (AgNPs) and 98.6% (ZnONPs), with co-loaded systems retaining 64.0% and 98.9%, respectively. Swelling was highest in AgNP-loaded microparticles (63.8%) and lowest in ZnONP and co-loaded systems (≈42%). AgNPs followed anomalous transport (n = 0.65), while ZnONPs transitioned from Fickian diffusion (n ≈ 0.36–0.38) to zero-order release (K₀ = 1.00 for ZnONPs alone; 0.80 co-loaded). Antifungal tests showed strong inhibition: 80.7% for AgNPs, 91.4% for ZnONPs, and 99.7% for co-loaded formulations. Microscopy confirmed membrane disruption, hyphal collapse, and ROS-mediated damage, with the strongest effects in co-loaded samples. These results demonstrate a tunable, synergistic, sustained-release platform that outperforms single nanoparticles and offers a promising strategy for sustainable crop protection. Full article

The versatility of emulsions as templates for fabricating functional materials has garnered significant attention in recent decades. Emulsions with tailored geometries provide a powerful platform for designing and synthesizing polymeric materials with diverse functionalities. This review summarizes recent advances in emulsion-mediated fabrication of block copolymer (BCP) functional colloids and emulsion-templated construction of gel emulsion and porous hydrogels. Key topics include the generation of high-quality, uniform emulsion droplets, control over the shape and internal nanostructure of BCP colloids, and strategies for constructing polymeric gels and other porous functional materials using gel emulsion as templates. Furthermore, the intrinsic properties of polymers can be pre-engineered with specific stimulus-responsive functionalities prior to the fabrication of polymeric microparticles or porous hydrogels, thus imparting novel and targeted functionalities to the resulting assemblies and porous networks. This study can help in developing crucial strategies and in identifying pathways for the rational design of novel multifunctional materials with applications in drug delivery, sensing, and catalysis. Full article

This study investigates the use of bio-based polyurethane foams (PUFs) containing phase change material (PCM) microparticles as a sustainable alternative for the automotive sector. These foams are synthesized using polyols derived from waste cooking oil (WCO), aligning with circular economy principles. To evaluate the thermophysical properties of these materials and, more in general, their thermal behavior, the use of non-destructive thermographic techniques has been proposed. This technique enables a rapid, full-field thermal analysis without physical contact, making it especially suitable for porous and heterogeneous structures like foams. As a reference, both virgin and foams with PCM were characterized in terms of density and thermal conductivity using well-established methods. Then, Lock-in thermography has been used as the first attempt technique to investigate variations in thermal behavior due to different thermophysical material properties based on the thermal response in transmission configuration. The thermographic approach proves to be an effective tool not only for assessing thermal behavior but also for supporting quality control and process optimization of sustainable polymeric materials. Full article

Background: Large porous particles (LPPs) offer significant potential in drug delivery due to their porous structure and suitable particle size and shape, which can improve powder dispersibility and control drug release. Methods: In this study, sustained-release large porous microparticles of mannitol, PVA, and diclofenac sodium (MPDs) were developed using a spray drying technique. The influence of PVA co-spray drying and its concentration (0–40%) on the characteristics of the spray-dried particles was investigated. Results: Co-spray drying with PVA enhanced particle morphology, producing MPDs with a spherical shape and smooth surface, which minimized particle adhesion. This improvement correlated with a low Carr’s Index value (17.56%), indicating favorable particle dispersibility and aerosol performance. The large geometric diameter (>5 μm) of the MPDs, coupled with their low bulk density (<0.1 g/cm³), suggested potential for inhalation use. FTIR, XRD, and DSC analyses revealed that PVA altered the polymorphic form of mannitol, with the MPDs exhibiting a mixture of the α and δ forms. In vitro dissolution tests demonstrated that PVA co-spray drying effectively prolonged drug release, with the formulation containing 40% PVA (MPD-4) showing an optimal release profile. The release kinetics followed first-order Higuchi models, suggesting drug release occurred through a matrix diffusion mechanism facilitated by the porous structure. Conclusions: These findings demonstrate the feasibility of engineering large porous microparticles with tailored release characteristics and physicochemical properties suitable for further development in inhalable or other controlled-release dosage forms. Full article

This study discloses the noncovalent immobilization of a bienzyme cascade composed of glucose oxidase (GOx) and horseradish peroxidase (HRP) onto magnetically responsive polyamide microparticles (PA MPs). Porous PA6, PA4, and PA12 MPs containing iron fillers were synthesized via activated anionic ring-opening polymerization in suspension, alongside neat PA6 MPs used as a reference. Four hybrid catalytic systems (GOx/HRP@PA) were prepared through sequential adsorption of HRP and GOx onto the various PA MP supports. The initial morphologies of the supports and the hybrid biocatalysts were characterized by SEM, followed by evaluation of the catalytic performance using a two-step glucose oxidation cascade process. Among all systems, the GOx/HRP@PA4-Fe complex exhibited the highest activity, being approximately 1.5 times greater than the native enzyme dyad, followed by the PA6-supported system with slightly inferior performance. All systems obeyed Michaelis–Menten kinetics, with the immobilized cascades displaying higher Kₘ and Vₘₐₓ values than the non-immobilized enzyme pair while maintaining comparable catalytic efficiencies, CE (CE = k_cat/Kₘ). Subsequently, the immobilized and native enzyme systems were employed for the polymerization of aniline. According to UV–VIS, complete monomer conversion was achieved within 24 h for selected catalysts, and FTIR analysis confirmed the formation of polyaniline in the emeraldine base form without the use of template molecules. These findings highlight the potential of Fe-containing polyamide microparticles as efficient supports for the sustainable, enzyme-mediated synthesis of intrinsically conductive aromatic polymers. Full article

This study presents a novel self-healing mechanism for porcelain ceramics using UV-curable resin to address the inherent brittleness of ceramic materials. A biomimetic double-layered structure was designed, consisting of a high-density outer layer for mechanical strength and a highly porous inner layer for resin storage. The porous layer, achieved through nylon microparticle addition and subsequent volatilization during sintering, reached a porosity of 67%. As confirmed by FT-IR spectroscopy and EDS analysis, UV-curable acrylic resin was successfully incorporated into the porous structure. Three-point bending tests demonstrated efficient healing with a recovery rate of 56% after 5 min of UV irradiation. Both cured resin weight and post-healing bending strength increased logarithmically with UV irradiation time. The bending strength after healing was strongly dependent on the cured resin weight and polymerization depth within the specimen, as evidenced by the correlation between increased polymerization area and higher bending strength. This approach offers a promising solution for developing more reliable and durable ceramic materials, which will be particularly beneficial for aerospace and medical applications where maintenance cost reduction and extended product life are crucial. Full article

Free pectinase is commonly employed as a biocatalyst in wine clarification; however, its removal, recovery, and reuse are not feasible. To address these limitations, this study focuses on the immobilization of a commercial pectinolytic preparation (Pec) onto highly porous polymer microparticles (MPs). Seven microparticulate polyamide (PA) supports, namely PA4, PA6, PA12 (with and without magnetic properties), and the copolymeric PA612 MP, were synthesized through activated anionic ring-opening polymerization of various lactams. Pectinase was non-covalently immobilized on these supports by adsorption, forming Pec@PA conjugates. Comparative activity and kinetic studies revealed that the Pec@PA12 conjugate exhibited more than twice the catalytic efficiency of the free enzyme, followed by Pec@PA6-Fe and Pec@PA4-Fe. All Pec@PA complexes were tested in the clarification of industrial rosé must, demonstrating similar or better performance compared to the free enzyme. Some immobilized biocatalysts supported up to seven consecutive reuse cycles, maintaining up to 50% of their initial activity and achieving complete clarification within 3–30 h across three consecutive cycles of application. These findings highlight the potential for industrial applications of noncovalently immobilized pectinase on various polyamide microparticles, with possibilities for customization of the conjugates’ properties. Full article

Flexible, wearable pressure sensors offer numerous benefits, including superior sensing capabilities, a lightweight and compact design, and exceptional conformal properties, making them highly sought after in various applications including medical monitoring, human–computer interactions, and electronic skins. Because of their excellent characteristics, such as simple fabrication, low power consumption, and short response time, capacitive pressure sensors have received widespread attention. As a flexible polymer material, polydimethylsiloxane (PDMS) is widely used in the preparation of dielectric layers for capacitive pressure sensors. The Young’s modulus of the flexible polymer can be effectively decreased through the synergistic application of sacrificial template and laser ablation techniques, thereby improving the functionality of capacitive pressure sensors. In this study, a novel sensor was introduced. Its dielectric layer was developed through a series of processes, including the use of a sacrificial template method using NaCl microparticles and subsequent CO₂ laser ablation. This porous PDMS dielectric layer, featuring an array of holes, was then sandwiched between two flexible electrodes to create a capacitive pressure sensor. The sensor demonstrates a sensitivity of 0.694 kPa⁻¹ within the pressure range of 0–1 kPa and can effectively detect pressures ranging from 3 Pa to 200 kPa. The sensor demonstrates stability for up to 500 cycles, with a rapid response time of 96 ms and a recovery time of 118 ms, coupled with a low hysteresis of 6.8%. Furthermore, our testing indicates that the sensor possesses limitless potential for use in detecting human physiological activities and delivering signals. Full article

A promising therapeutic option for the treatment of critical-size mandibular defects is the implantation of biodegradable, porous structures that are produced patient-specifically by using additive manufacturing techniques. In this work, degradable poly(DL-lactide) polymer (PDLLA) was blended with different mineral phases with the aim of buffering its acidic degradation products, which can cause inflammation and stimulate bone regeneration. Microparticles of CaCO₃, SrCO₃, tricalcium phosphates (α-TCP, β-TCP), or strontium-modified hydroxyapatite (SrHAp) were mixed with the polymer powder following processing the blends into scaffolds with the Arburg Plastic Freeforming 3D-printing method. An in vitro degradation study over 24 weeks revealed a buffer effect for all mineral phases, with the buffering capacity of CaCO₃ and SrCO₃ being the highest. Analysis of conductivity, swelling, microstructure, viscosity, and glass transition temperature evidenced that the mineral phases influence the degradation behavior of the scaffolds. Cytocompatibility of all polymer blends was proven in cell experiments with SaOS-2 cells. Patient-specific implants consisting of PDLLA + CaCO₃, which were tested in a pilot in vivo study in a segmental mandibular defect in minipigs, exhibited strong swelling. Based on these results, an in vitro swelling prediction model was developed that simulates the conditions of anisotropic swelling after implantation. Full article

Despite recent clinical successes in cancer immunotherapy, it remains difficult to initiate a long-term anti-tumor effect. Therefore, repeated administrations of immune-activating agents are generally required in most cases. Herein, we propose an adjuvant particle size tuning strategy to initiate a long-term anti-tumor effect by one-shot vaccination. This strategy is based on the size-dependent immunostimulation mechanism of mesoporous silica particles. Hollow mesoporous silica (HMS) nanoparticles enhance the antigen uptake with dendritic cells around the immunization site in vivo. In contrast, hierarchically porous silica (HPS) microparticles prolong cancer antigen retention and release in vivo. The size tuning of the mesoporous silica adjuvant prepared by combining both nanoparticles and microparticles demonstrates the immunological properties of both components and has a long-term anti-tumor effect after one-shot vaccination. One-shot vaccination with HMS-HPS-ovalbumin (OVA)-Poly IC (PIC, a TLR3 agonist) increases CD4⁺ T cell, CD8⁺ T cell, and CD86⁺ cell populations in draining lymph nodes even 4 months after vaccination, as well as effector memory CD8⁺ T cell and tumor-specific tetramer⁺CD8⁺ T cell populations in splenocytes. The increases in the numbers of effector memory CD8⁺ T cells and tumor-specific tetramer⁺CD8⁺ T cells indicate that the one-shot vaccination with HMS-HPS-OVA-PIC achieved the longest survival time after a challenge with E.G7-OVA cells among all groups. The size tuning of the mesoporous silica adjuvant shows promise for one-shot vaccination that mimics multiple clinical vaccinations in future cancer immunoadjuvant development. This study may have important implications in the long-term vaccine design of one-shot vaccinations. Full article

The use of free pectinases as clarification biocatalysts constitutes a well-established practice in the large-scale production of various types of wines. However, when in the form of free enzymes, the recovery and reusability of pectinases is difficult if not impossible. To address these limitations, the present study focuses on the noncovalent adsorption immobilization of a commercial pectinolytic preparation onto highly porous polyamide 6 (PA6) microparticles, both with and without magnetic properties, prepared via activated anionic polymerization. The two pectinase complexes resulting after immobilization underwent comparative activity and kinetic studies, contrasting them with the free enzyme preparation. In comparison with the free enzyme, the PA6-immobilized pectinase complexes exhibited more than double the specific activity toward the pectin substrate. They displayed a slightly higher affinity to the substrate while acting as faster catalysts that were more resistant to inhibition. Furthermore, the immobilized complexes were applied in the clarification process of industrial rosé must, whereby they demonstrated accelerated performance as compared with the free enzyme. Moreover, the PA6-immobilized pectinase biocatalysts offered the potential for three consecutive cycles of reuse, achieving complete rosé must clarification within relevant timeframes in the range of 3–36 h. All these results suggest the potential industrial application of the pectinases noncovalently immobilized upon PA6 microparticles. Full article