The influence of titania/hydroxyapatite composite coatings on in vitro osteoblasts behaviour

The biocompatibility of titania,hydroxyapatite (TiO2/HA) composite coatings , at different ratio obtained by sol-gel process, were investigated studyin g the behaviour of human MG63 osteoblast-like cells. The biocompatibility w as evaluated by means of cytotoxicity and cytocompatibility tests. Cytotoxi city tests, i.e., neutral red (NR), MTT and kenacid blue (KB) assays, were performed to assess the influence of the material extracts on lysosomes, mi tochondria and cell proliferation, respectively. Cell proliferation, some p reliminary indications of cell morphology, alkaline phosphatase activity, c ollagen and osteocalcin production of MG63 cells, cultured directly onto Ti O2/HA substrates, were evaluated. The results showed that these materials h ave no toxic effects. Cell growth acid morphology were similar on all the m aterials tested; on the contrary, alkaline-phosphatase-specific activity an d collagen production of osteoblasts cultured on TiO2/HA coatings were sign ificantly higher than uncoated titanium and polystyrene of culture plate an d were influenced by chemical composition of the coatings. In particular, T iO2/HA coating at 1:1 ratio (w/w) seems to stimulate more than others the e xpression of some differentiation markers of osteoblastic phenotype. TiO2/H A coatings resulted to be bioactive owing to the presence of hydroxyl group s detected on their surface that promote the calcium and phosphate precipit ation and improve the interactions with osteoblastic cells. (C) 2001 Elsevi er Science Ltd. All rights reserved.