A Self-Transformed N-Chlorinated ε-Polylysine Coating Endows Titanium Implants with Programmed Integration of Robust Antibacterial and Pro-Osteogenic Abilities

Implant-associated infection and poor osseointegration are the main causes of orthopedic implantation failure. For a long-term successful implantation, simultaneously introducing prevention of infection and promotion of osteogenesis into implants is highly desired but remains a grand challenge. Inspired by the human immune mechanism of tissue repair under bacterial infection, we propose a self-transformed strategy for the modification of titanium with porous N-chlorinated ε-polylysine coating (Ti-PL-NCl) through pore-making, surface grafting and chlorination. The as-prepared Ti-PL-NCl exhibits an excellent antibacterial activity against S. aureus and E. coli in the presence of N-chloramine in the early stage, with an antibacterial rate as high as 95.8% and 99.4%, respectively. With the consumption of oxidative chlorine, the N─Cl groups of Ti-PL-NCl are transformed into N─H groups with moderate antibacterial yet strong pro-osteogenic abilities. The self-transformed N-chlorinated ε-polylysine coating enables Ti-PL-NCl to achieve long-lasting antibacterial activity as well as enhanced pro-osteogenesis, thus providing adaptive bioactivities for bone-implant integration. Rat implant-associated osteomyelitis model confirms that Ti-PL-NCl has excellent efficacy of infection prevention and osseointegration promotion. This work may provide a new paradigm of designing multifunctional implants to achieve long-term successful implantation.