As a natural high-performance material with a unique hierarchical structure, silk is endowed with superior mechanical properties. However, the current approaches towards producing regenerated silk fibroin (SF) for the preparation of biomedical devices fail to fully exploit the mechanical potential of native silk materials. In this study, using a top-down approach, we exfoliated natural silk fibers into silk nanofibrils (SNFs), through the disintegration of interfibrillar binding forces. The as-prepared SNFs were employed to reinforce the regenerated SF solution to fabricate orthopedic screws with outstanding mechanical properties (compression modulus > 1.1 GPa in a hydrated state). Remarkably, these screws exhibited tunable biodegradation and high cytocompatibility. After 28 days of degradation in protease XIV solution, the weight loss of the screw was ~20% of the original weight. The screws offered a favorable microenvironment to human bone marrow mesenchymal stem cell growth and spread as determined by live/dead staining, F-action staining, and Alamar blue staining. The synergy between native structural components (SNFs) and regenerated SF solutions to form bionanocomposites provides a promising design strategy for the fabrication of biomedical devices with improved performance.

This study reports process optimization studies of silica and zinc oxide-based flame-retardant (FR) coatings on cotton fabric for protective clothing and enhanced flammability properties. The experiments were designed by central composite design (CCD) using response surface methodology (RSM) to assess the synergistic protective effects of silica and zinc oxide FR coating. These prepared sols were coated on cotton fabrics by a simple dip dry cure process. The resulting FR-finished fabrics were characterized by SEM, mechanical properties, flame retardancy, and air permeability. SEM results confirmed the homogenous spreading of particles on cotton fabrics. From TGA results, it was noticed that the incorporation of silica and ZnO in the prepared nano-sols results in improved thermal stability of the FR-finished fabrics. These sol–gel-treated FR cotton fabrics showed excellent comfort properties, which shows their suitability for fire-retardant protective clothing. RSM analysis proved that the predicted values are in good agreement with the experimental values since R² values for time to ignite, flame spread time, and air permeability were greater than 0.90. The optimized concentration of silica and ZnO in FR-finished fabrics was found to be 0.302% and 0.353%, respectively, which was further confirmed by confirmatory experiments. The optimization analysis successfully optimized the process for synergistic coating of silica and zinc oxide nanoparticles for enhanced flammability properties of FR cotton fabric for protective clothing.

The accumulation of discarded denim waste in landfills is causing environmental pollution, creating an urgent need for sustainable solutions. This study demonstrates the recycling of denim by extracting the indigo dye and fabricating the treated fabric into a composite to develop eco-friendly and high-performance materials. The waste denim was treated with sodium borohydride under controlled conditions without damaging the fibers. To utilize the denim waste, the decolorized fabric was shredded into fibers and incorporated into two polymer matrices i.e., ethylene vinyl acetate (EVA) and vinyl acetate, (VA) to fabricate a fiber-reinforced composite. The prepared recycled denim composites were compared with composites based on raw cotton fibers. The surface morphology of the composites was studied through optical microscopy and SEM analysis to examine the structural properties. Mechanical tests including tensile, charpy impact, flexural bending and drop-weight tests were performed to evaluate performance. The results showed that the raw composite had a higher impact strength of 11.5 kJ/m², while the recycled composite had 9.89 kJ/m², showing a slight reduction but maintaining good mechanical strength and lightweight properties suitable for applications such as table tennis rackets, a sustainable sports product, thereby supporting a closed-loop denim recycling approach within a circular economy framework.