Phenol-amine Crosslinking Coating With Chlorhexidine Improved The Antibacterial Properties Of Titanium

Objective Chlorhexidine is widely used because of its strong antibacterial properties,and its long-term antibacterial efficacy is suitable for biological inert medical devices.However,chlorhexidine molecules need a cross-linked membrane to be able to stabilize on the surface of bio-inert metals.Therefore,chlorhexidine was fixed on the titanium alloy after alkaline heat treatment,supplemented by phenol-amine crosslinking coating as the intermediate layer,which retained good cell compatibility and had good antibacterial effect.This study aims to investigate the preparation of phenol-amine crosslinking coating on titanium surface with chlorhexidine,explore the physical and chemical properties of the constructed surface,and evaluate its in vitro antibacterial activity and osteoblast compatibility.Methods After alkaline heat treatment(control group)of pure titanium,EGCG and hexanediamine(HD)were crosslinked on the surface of titanium substrate after alkaline heat treatment by chemical bond crosslinking(coating group).The coating group was immersed in chlorhexidine solution to obtain chlorhexidine grafting surface(grafting group).The surface morphology of the samples was photographed by SEM.XPS instrument was used to measure the composition and content of elements on the sample surface.Surface hydrophilicity was analyzed by WCA.The antibacterial properties were evaluated by live / dead bacterial staining,turbidity method and inhibition zone method.The cytotoxic was evaluated by MTT assay and fluorescence staining.Bacterial-cell co-culture was used to evaluate the cell adhesion ability of the material surface under the coexistence of bacteria and cells.Results SEM showed that deposits of coating group and grafting group increased successively and gradually covered the porous structure.WCA showed that hydrophilicity decreased with modification,and there was significant difference between groups(P<0.05).XPS showed the peaks of Cl and N appeared in grafting group.Live-dead bacteria staining showed that the grafting group had the least amount of bacteria adhered to the surface and the proportion of dead bacteria was high.The grafting group had a transparent inhibition zone around it and the absorbance value did not increase.Cell-culture results showed that the number of adherent cells on the surface of the grafted group was the least,but the adherent cells had good proliferation activity.Bacteria-cell co-culture showed that there was no bacteria on the surface of grafting group and live cells adhered well.Conclusion In this study,the cross-linked coating was successfully constructed on the titanium surface after alkali heat treatment by the reaction of phenolic hydroxyl and amine under alkaline conditions,and chlorhexidine was grafted by soaking chlorhexidine aqueous solution.Finally,the antibacterial surface was constructed on the titanium surface.This surface not only inhibit the adhesion of bacteria on the sample surface,but also inhibit the proliferation of bacteria around the sample,which can avoid the infection caused by the introduction of bacteria into the implant or the migration of bacteria around the implant.It can facilitate the preferential adhesion of osteoblasts in the bacterial environment to promote osteogenic effect of the implant,effectively improve the success rate of bone implants and reduce the risk of infection.