A chronological regulated implant coating with antibacterial and osteogenesis constructed by TA-mediated LbL self-assembly

Numerous surface modification strategies for ordinary titanium (Ti) implant have been proposed since Ti lacks antibacterial and osteogenic characteristics. However, the majority of surface modifying materials currently do not consider the microenvironmental demands that are constantly changing ——Antibacterial is required at the early stage after implantation and osteogenesis becomes an intense appeal at the later stage. In the present study, strontium ranelate (SrR) and chitosan (CTS) were loaded onto the titanium surface via layer-by-layer (LbL) self-assembly based on tannic acid (TA) with separate antimicrobial and osteogenic layers. The obtained Titanium-Strontium Ranelate-Chitosan (Ti-SrR-CTS) implant achieved an outstanding early-stage antibacterial effect against S. aureus and E. coli and a more prominent late-stage osteogenic effect than ordinary titanium implant in vitro. In vivo results further verified that Ti-SrR-CTS implants had 97.68% antibacterial efficacy and 1.82 times the amount of new bone compared to ordinary titanium at different stages, respectively. This work has successfully designed a novel implant coating with both excellent antimicrobial and osteogenic properties, which provides a promising surface modification strategy for orthopedic applications.