Evaluation Of Polydopamine/Hyaluronic Acid Composite Membrane Modified Vancomycin-Loaded Titania Nanotubes Coating For Prevention Of Orthopedic Implant-Related Infection

Background and objectiveTitanium and its alloys are widely used in the fixation of fracture and prosthesis implantation,but they lack the ability of anti-infection.Orthopedic implant-related infection is difficult to treat and often leads to surgical failure,so it is very important to prevent the infection.Local anti-infection by surface modification of implants is a hot research topic in the prevention of implant-related infection.The preparation process of titania nanotubes is simple,and the tube-like structure can be used to load antimicrobial agents.However,its clinical application is hindered by the limited drug loading capacity and the uncontrollable drug release.The purpose of this study was to construct a polydopamine/hyaluronic acid composite membrane to modify vancomycin-loaded titania nanotubes,which not only gave the coating good biocompatibility,but also increased the drug loading,drug release and antibacterial properties of the coating under infection conditions.The antibacterial properties,biocompatibility and osteogenesis ability of polydopamine/hyaluronic acid composite membrane modified vancomycin-loaded titania nanotubes(Ti-NT-VCM-pDA-Hya)coating were tested in vitro and in vivo.MethodsThe titania nanotubes(Ti-NT)with nano-tubular structure are fabricated by anodization.Vancomycin was loaded into the nanotube cavity through vacuum lyophilization,and the surface of the Ti-NT was modified by the polydopamine/hyaluronic acid composite membrane.The surface structure of the coating was observed and photographed by scanning electron microscope(SEM)and infrared microscope.Drug release experiments were used to study the release properties of Ti-NT-VCM-pDA-Hya coating and the effect of acidic conditions(pH=6)on the drug release.The in vitro antibacterial properties of Ti-NT-VCM-pDA-Hya coating were evaluated by spread-plate method to quantitatively characterize the number of viable bacteria and Live/Dead viability staining.The adhesion and proliferation of rat bone marrow mesenchymal stem cells(RBMSCs)on the surface of Ti-NT-VCM-pDA-Hya coating were investigated by cell counting kit-8(CCK-8)test.The effect of Ti-NT-VCM-pDA-Hya coating on osteogenic differentiation of RBMSCs was evaluated by alkaline phosphatase(ALP)staining,alizarin red staining and rat quantitative analysis of marker genes for osteogenic differentiation by RNA.Finally,the anti-infection ability of Ti-NT-VCM-pDA-Hya coating in vivo was evaluated by means of gross observation,imaging detection,microbiological analysis and micro-CT analysis on the infection model of the rat femoral implant.ResultsSEM and infrared microscopy showed that the surface of titania nanotubes was successfully modified by polydopamine/hyaluronic acid-loaded vancomycin composite membrane.Drug release experiments confirmed that the Ti-NT-VCM-pDA-Hya coating had higher drug release,which could release a large amount of vancomycin rapidly in the early stage,slowly in the later stage,and could be released continuously in vitro for one week;In the simulated infection environment(p H=6),the Ti-NT-VCM-pDA-Hya coating had higher vancomycin release.In vitro antibacterial experiments showed that the Ti-NT-VCM-pDA-Hya coating could inhibit the adhesion and proliferation of Staphylococcus aureus and the formation of bacterial biofilm.Biocompatibility and osteogenic differentiation experiments showed that Ti-NT-VCM-pDA-Hya coating could promote the late proliferation and osteogenic differentiation of RBMSCs.The results of animal experiments showed that the Ti-NT-VCM-pDA-Hya coating could effectively inhibit the infection around the femoral implant and reduce the bone resorption caused by the infection.ConclusionThe Ti-NT-VCM-pDA-Hya coating has higher drug loading and better drug release performance,and the acidic condition can increase the drug release of the coating,indicating that the coating design is reasonable and the preparation scheme is feasible.Ti-NT-VCM-pDA-Hya coating can exert good antibacterial effect in vivo and in vitro,has good biocompatibility and can promote osteogenic differentiation,so it has good clinical application value.