Synergistic tannic acid/dopamine interfacial bridging enables a silk fibroin coating on degradable zinc implants

This study develops a tannic acid/polydopamine/silk fibroin (TA/PDA/SF, TSF) multilayer coating on zinc (Zn) substrates via a synergistic interfacial bridging strategy. The TA/DA interfacial bridging enables rapid coating assembly and stable SF integration. The TSF coating exhibits a critical load ( L c ) of 12 N, approximately twice that of PSF, and achieves the lowest corrosion current density (0.89 μA·cm −2 ) among all groups. Cellular evaluation using MC3T3-E1 pre-osteoblasts demonstrates that TSF not only maintains cell viability even in undiluted extracts but also promotes osteogenic differentiation, as evidenced by enhanced alkaline phosphatase activity and matrix mineralization. This work demonstrates favorable interfacial bonding, corrosion resistance and osteogenic activity of TSF, providing a simple strategy for the surface modification of biodegradable Zn-based orthopedic implants.