| Bacteria-associated infection represents one of the major threats for orthopedic implants failure during their life cycles.However,ordinary antimicrobial treatments usually failed to combat multiple waves of infections during arthroplasty and prosthesis revisions etc.as these incidents could easily introduce new microbial pathogens in/onto the implants.In the first part,we load effective iodine on the surface of titanium alloy through micro-arc oxidation,electrophoresis and redox reaction,and then build a coating that can control iodine release through PCL.Besides,we explore the biocompatibility of the coating system,controlled release performance of iodine and long-term antibacterial properties.The PCL coating has good biocompatibility and gradually degrades after being implanted in the body.At the same time,it is accompanied by the slow release of iodine,which effectively kills the possible residual bacteria around the implant and reduce the risk of potential infection.Due to the controlled release effect of the PCL coating,the coating system still has an effective iodine release concentration on one month after implantation,thus effectively exerting a long-term antibacterial effect.In the second part,we demonstrate that an antimicrobial trilogy strategy incorporating a sophisticated multilayered coating system leveraging multiple ion exchange mechanisms and fine nanotopography tuning,could effectively eradicate bacterial infection at various stages of implantation.Early stage bacteriostatic effect was realized via nano-topological structure of top mineral coating.Antibacterial effect at intermediate stage was mediated by sustained release of zinc ions from doped Ca P coating.Strong antibacterial potency was validated at 4 weeks post implantation via an implanted model in vivo.Finally,the underlying zinc titanate fiber network enabled a long-term contact and release effect of residual zinc,which maintained a strong antibacterial ability against both Staphylococcus aureus and Escherichia coli even after the removal of top layer coating.Moreover,sustained release of Sr2+and Zn2+during Ca P coating degradation substantially promoted implant osseointegration even under an infectious environment by showing more peri-implant new bone formation and substantially improved bone-implant bonding strength.In summary,the research of this thesis mainly studies the antibacterial multifunctional coating on the surface of orthopedic implants to achieve long-term antibacterial properties and high-efficient osseointegration. |
