Antioxidative and antibacterial gallium (III)-phenolic coating for enhanced osseointegration of titanium implants via pro-osteogenesis and inhibiting osteoclastogenesis

Improving the ability of implants to integrate with natural bone tissue at the initial stage of implantation remains a huge challenge because bone-to-implant interfaces are often accompanied by abnormal microenvironments with infection, reactive oxygen species (ROS) and unbalanced bone homeostasis. In this study, a multifunctional coating was fabricated on the basis of gallium (III)-phenolic networks. It is easily obtained by immersing the implants into a mixed solution of tannic acids (TAs) and gallium ions. The thickness of the coating can be precisely controlled by adjusting the number and time of immersion experiments. The resulting coating displays excellent near-infrared photothermal property. As the coating degrades, TAs and gallium ions with low concentration are released from the coating, which is more rapid in acidic and oxidative stress microenvironments. Photothermal performance as well as released TAs and gallium ions give the coating outstanding broad-spectrum antibacterial ability. Furthermore, the coating effectively reduces intracellular ROS of osteoblasts. In vitro and in vivo experiments demonstrate the capability of the coating enhancing implants' osseointegration via pro-osteogenesis and inhibiting osteoclastogenesis. The findings imply that gallium (III)-phenolic coating holds great promise to promote implant osseointegration by rescuing abnormal microenvironments of infection, oxidative stress and unbalanced bone homeostasis.