Bioactivity On Titanium Surface With Phosphorus

Titanium and its alloys have been applied in orthopedics more and more owing to its biocompatibility, mechanical and the physical properties.To improve the bioactivity of the materials surface, people have paid attention to the surface modification on the titanium and its alloys nowadays. In this study, the titanium specimens were treated with H₃PO₄ and triethyl phosphate(TEP), respectively. The role of phosphorus on titanium surface in biomineralization was investigated. And another way, one or two protein were adsorbed onto the surface with phosphorus. The surface adsorption kinetics and competitive adsorption mechanism was studied. Behaviors of osteoblast on the titanium surface with phosphorus were evaluated in vitro before and after protein adsorbed..After titanium was phosphated with H₃PO₄ and TEP, the elements of P, C, 0, Ti and the radicles of P-O-C, -PO₃, -PO₄ were detected by X-ray photoelectron spectroscopy (XPS) and the Fourier transformed infrared spectroscopy (FTIR). It presents that the phosphorus had been bonded onto the titanium surface with chemical combination. The biomineralization suggested that the phosphorus was an important promoter to hydroxyapatite (HA) deposition. Meanwhile, the specimens were immersed into the Ringers solution without phosphorus, the HA were also found. So it shows the phosphorus could induce the HA deposition. The scanning electron microscopy(SEM) and X-ray diffraction (XRD) analyses indicated that HA uniformly distributed on the titanium surface, and had good crystallinity.When materials implant into the body, first of all, the reaction will happen between the specimen and proteins. So in this study, different pH values, initial concentrations and times of adsorption were chosed to explore the mechanism of the protein adsorption. The results suggested that the adsorption velocity and quantity were affected by the pH at the initial stage when the only one protein was adsorbed. Because of the hydrophobic surface with phosphorus, the BSA could adsorbed much more easily than collagen I. But when two proteins coexisted, the XPS and FTIR analses indicated that proteins covalently adsorbed onto the surfaces. Then the maximal adsorption quantities were calculated through the Langumir isotherm model.The osteoblast culture test in vitro showed there was higher cell activity on the surface modified by the phosphating treatment. And the activity of cell on the surface containing proteins was higher than that without the BSA or/and Collagen I . It indicated that the BSA or/and Collagen I to promote cell adhesion, spread and colonization. However, the different proteins could present the different effects to the cell, the BSA was helpful to cell proliferation, while the Collagen I promoted to cell differentiation. But when the two coexisted, they would be mutual promotion.