Despite significant advances in wound dressing materials, a critical challenge remains in developing a single multifunctional platform that simultaneously provides mechanical integrity, controlled bioactive delivery, and broad-spectrum antimicrobial protection for complex and infected wounds. To address this gap, the present study synthesized and evaluated an innovative alginate-chitosan-based composite hydrogel reinforced with hydroxyapatite nanoparticles (HA) and thyme extract (Thymus vulgaris) for advanced wound dressing applications. The primary goal was to create a multifunctional system with optimized mechanical, swelling, biological, and antimicrobial properties. FESEM analyses revealed a uniform distribution and porous morphology in the final sample (Alg/HA/Chi/Ext), while XRD results confirmed a gradual decrease in crystallite size and crystallinity degree from 89.5% for pure HA to 21.7% for the final composite, indicating enhanced amorphous character and intermolecular interactions. Tensile testing demonstrated a significant improvement in the UTS (50 MPa) and, notably, toughness (1087.5 kJ/m³) of the final sample compared to pure alginate hydrogel. This composite exhibited high swelling capacity (766%) similar to pure alginate, but with much better structural stability. The MTT assay confirmed superior biocompatibility and increased cell viability (88% after 72 hours). Release studies showed a biphasic profile for the final sample, which followed the Korsmeyer-Peppas kinetic model. Significantly, this hydrogel demonstrated potent antimicrobial activity against Bacillus cereus (98.99% inhibition) and the fungus Aspergillus flavus (99.12% inhibition), with very low MIC values (below 5 µg/mL). The developed Alg/HA/Chi/TE hydrogel exhibited significantly enhanced antimicrobial activity (p < 0.05) and superior extract-loading capacity compared with the other formulations, while maintaining controlled release behavior and acceptable biodegradation characteristics. These findings demonstrate the potential of the proposed multifunctional composite as a promising platform for sustained delivery of natural therapeutics in wound-healing applications. Nevertheless, further in vivo studies and sterilization validation are required before clinical translation.
The skin as the largest human organ serves several functions, such as natural protection against internal as well as external environmental influences. Three-dimensional (3D)-tissue engineering has emerged as a promising approach for the development of functional and physiologically relevant dermis substitutes. Mimicking the topography of the dermis to develop a skin-niche model (SKN) that contains epidermal stem cells is still a challenge. This study aimed to develop a dermis equivalent featuring a physiologically relevant dermal-epidermal junction (DEJ) topography; hence, a pattern was printed using 2-photon polymerization (2PP). The depth of the invaginations can influence cell differentiation and proliferation of epidermal stem cells. The template was subsequently translated into a dermis equivalent (DE). The human neonatal dermal fibroblasts (HDFn) remodeled the DE over 14 days, resulting in reduced dimensions that remained within the physiological range. The DE contains gelatin methacrylate (GelMA) and proliferating fibroblasts that produce extracellular matrix (ECM). In a proof-of-concept, N/TERT-1 keratinocytes, as the epidermal layer, were seeded on the patterned DE to verify the adhesion and proliferation of keratinocytes on the DE. Overall, this approach enables the generation of a DE with a natural DEJ, as a more physiological skin model for future use in disease modeling, drug development, screening, and skin transplantation.
Hydrogel-based advanced wound dressings promote rapid healing by creating a moist environment and protecting against contamination. However, pure hydrogel often lacks strength, flexibility, and wearer comfort for practical clinical use. To address these limitations, this study developed a gelatin hydrogel reinforced with wool fibrous nonwoven. The addition of wool fibers improved thermal comfort, structural integrity, and overall performance of the hydrogel system. Using a sol–gel technique, wool nonwovens with different areal densities (100–300 g/m2) were incorporated into gelatin matrices at varying concentrations (1–5%) to fabricate robust composite dressings. The composites were subjected to morphological, thermal, mechanical, permeability, absorption, antimicrobial, and in vivo evaluations. The fabricated composites demonstrated superior exudate absorption, increased mechanical strength, and elevated air permeability. In vivo investigations revealed that treated wounds significantly outperformed control groups by achieving 98% closure within 21 days. The statistical analysis confirmed that gelatin concentration had the predominant effect on strength and absorption properties, with wool reinforcement playing a pivotal role in improving breathability. These results indicate that wool-reinforced gelatin hydrogel composites offer an optimal integration of mechanical robustness, biocompatibility, and multifunctionality, positioning them as a promising material for advanced wound-dressing applications.
This manuscript introduces a novel biosystem consisting of filamentous fungi and luminescent silicon nanoparticles (Si-NPs). The microorganisms were cultivated in a nutrient solution containing Si-NPs, acquiring a dense layer of abiotic material. The biohybrid entities were characterized using a combination of microscopy and spectroscopy techniques. Intriguingly, in addition to incorporating Si-NPs into the fungal cell wall, we observed the internalization of these nanoparticles within fungal organelles. Moreover, the apparent crystallite size of the Si-NPs within the fungal biohybrids was notably smaller than that of the synthesized Si-NPs, indicating that, under the cultivation and preparation conditions, microorganisms assimilate smaller Si-NPs more readily than larger ones. Consequently, nanoparticles smaller than 10 nm may permeate the cell wall and be concentrated in vacuoles, as observed by fluorescence microscopy.
