In vitro study of surface functionalization of titanium substrates for potential enhancement of osseointegration and reduction of bacterial infection

Abstract

Different surface modification methods were investigated with the objective of reducing titanium orthopedic implant failure by enhancing osseointegration and reducing bacterial infections. Firstly, the surface of titanium was converted to anatase to reduce bacterial adhesion. However, the surface anatase was cytotoxic to osteoblasts, making it unsuitable for orthopedic applications. A second strategy was then developed, which involved the covalent immobilization of antibacterial polysaccharides and vascular endothelial growth factor (VEGF) on titanium. Such functionalized surfaces simultaneously reduced bacterial adhesion and enhanced osteoblast functions. To retain the bioactivity of VEGF, heparin-VEGF interaction was used for the VEGF immobilization. This technique resulted in higher VEGF bioactivity on both vascular and osseous functions, and the immobilized heparin also reduced bacterial adhesion. Lastly to address the issue of fibrous encapsulation which may impede osseointegration, alendronate was loaded on titanium. This alendronate-modified surface was shown to suppress fibroblast growth in a coculture of fibroblasts and osteoblasts.