Bone-Induced Nanocomposite Coating with a “Sandwich” Structure

Infection-induced bone defects present significant challenges in clinical bone regeneration, frequently leading to poor bone induction, recurring infections, and complications such as pain and chronic inflammation. This study introduces a novel Ti/Lignin-Ag@PLL composite coating with a “sandwich” structure, designed to integrate pro-adhesion, photothermal-photodynamic antibacterial, and osteogenic properties. The Ti/Lignin-Ag@PLL composite coating is fabricated using self-assembly technology, in which Ag⁺ is reduced to silver nanoparticles (Ag-NPs) by lignin, followed by Polylysine (PLL) grafting. Photothermal conversion efficiency is evaluated under near-infrared (NIR) laser irradiation, while antibacterial activity is tested against E. coli and S. aureus. Biocompatibility is also assessed using vascular endothelial cells (VECs) and osteoblasts (OBs). The results indicate that the Ti/Lignin-Ag@PLL coating demonstrates a 31% photothermal conversion efficiency and nearly 100% antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under NIR irradiation for 10 min. Without irradiation, the antibacterial rates are 85% and 94%, respectively, after 24 h. Additionally, the coating significantly promotes cell adhesion, proliferation, and osteogenesis, as evidenced by the upregulation of Runx2 and Collagen I. This study uniquely contributes to the development of a multifunctional composite coating that effectively combines robust antibacterial properties with enhanced osteogenic potential, offering a promising solution for bone tissue repair and infection prevention.