Biomimetic collagen/apatite coating formation on Ti6Al4V substrates

Hydroxyapatite and type I collagen are two major components of natural bone. They have been used extensively to engineer biomaterial surfaces for enhanced implant-bone integrations. In this study, a collagen/apatite composite coating was successfully deposited on treated Ti6Al4V surfaces by coprecipitation of type I collagen and apatite in a collagen-containing modified simulated body fluid (m-SBF). X-ray diffraction and Fourier-transform infrared spectroscopy results indicated that the coating achieved was a composite of bone-like carbonated apatite and collagen type I, which is similar to the composition of natural bone. The coating composition and morphology could be tailored by carefully adjusting the collagen concentration in the m-SBF. In addition, both the coating thickness and bonding strength were down regulated by the collagen concentration in the m-SBF. Collagen inhibited the apatite nucleation on the metallic substrate, and thereby reduced the bonding strength of the composite coating. In addition, an in vitro cell culture study was conducted on both the apatite and the collagen-apatite coating surfaces. Addition of collagen promoted osteoblast activities, which may lead to early bone formation.