IN VITRO STUDY OF SURFACE FUNCTIONALIZATION OF TITANIUM FOR ENHANCEMENT OF OSTEOBLAST AND STEM CELL FUNCTIONS

Abstract

Titanium (Ti) and its alloys are currently the most widely used orthopedic implantable materials. In this study, different surface modification approaches were carried out to enhance the osteogenesis of osteoblasts and stem cells cultured on Ti. Firstly, surface anchors (silane, dopamine and polydopamine) and surface coatings (carboxymethyl chitosan (CMCS) and bone morphogenetic protein 2 (BMP-2)) were immobilized on Ti. The stability of the surface anchors and coatings after being subjected to 70% ethanol, autoclaving and prolonged immersion in phosphate buffered saline was studied. Next, alendronate was immobilized on Ti via two conjugation strategies, and the effect of immobilized alendronate on osteoblast functions was compared. Thirdly, alkaline phosphatase was covalently bonded on CMCS-modified Ti to achieve a bifunctional substrate that enhances osteoblast and stem cell functions and reduces the adhesion of Staphylococcus epidermidis. Lastly, nanotubular Ti with surface-immobilized BMP-2 was used in conjunction with electrical stimulation to further enhance osteoblast functions.