Surface modification of titanium implants by pH-Responsive coating designed for Self-Adaptive antibacterial and promoted osseointegration

The development of responsive antibacterial implants is of high significance for the treatment of implant-associated infections. In this study, a self-adaptive antibacterial Ti-based implant with pH-sensitive coating was flexibly designed and constructed, with the dual functions of antibacterial and promoted osseointegration. The pH-sensitive antibacterial copolymer containing cationic quaternary ammonium salts (QAs) and carboxyl groups was firstly synthesized. Then, the prepared copolymer was coated on the surface of Ti metal by a simple layer-by-layer (LBL) self-assembly method to construct an antibacterial coating. The surface charge reversal was caused by the acidic microenvironment induced by the infected bacteria. The positively charged QAs possessed excellent antibacterial property against E. coli and S. aureus in vitro. The negatively charged carboxyl groups promoted the adhesion, proliferation and osteogenic differentiation of MC3T3-E1 cells in vitro. And the results of a S. aureus infection rat model further confirmed that the coated screws possessed good abilities of antibacterial and anti-inflammatory of implantation, and showed good osteointegration performance compared with the control ones. This strategy of self-adaptive antibacterial coating will provide a potential application for the prevention of Ti implant-associated bacterial infections.