Janus Nanocomposite for Enhanced Bone Tissue Engineering: Polyurethane Nanofibers with Zoledronic Acid–Silk Fibroin and Silver-Infused Chitosan Hydrogel

This work presents a hybrid material composed of a physically cross-linked poly(vinyl alcohol)/chitosan hydrogel with a pore size of 35 ± 10 nm loaded with silver (Ag) nanoparticles (NPs) with a diameter of 83.4 nm. This hydrogel is physically integrated with polyurethane (PU) nanofibers with an average diameter of 0.93 ± 0.5 μm that is preloaded with silk fibroin (SF)-encapsulated zoledronic acid (ZA) NPs (99.11 nm). However, the hybrid composites are hydrophilic, showing contact angles of <90^o due to incorporating hydrogel and NPs. Ultraviolet-visible spectrophotometry demonstrates a burst release of ZA from SF NPs within the first 6 h, followed by sustained release up to 48 h, after which the release rate declined. The degradation of hybrid composites in phosphate-buffered saline (PBS), protease type XIV, and human plasmin shows an increased degradation in the enzyme solutions of protease type XIV (42.6 ± 1.4%) and plasmin (52.6 ± 1.1%) than PBS (27.5 ± 1.9%) after 40 days. Biocompatibility is assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and staining, revealing viability of >300% and a higher cell density than the pure PU scaffold. These results suggest that the composite scaffolds offer a highly effective release of loaded NPs are suitable for healthcare products and devices for tissue engineering applications, especially deep wound defects involving bone injuries.