Phosphonate-Collagen Layer By Layer Modification On Medical Titanium Surface And Its Biological Properties

Titanium (Ti) and its alloys have been widely applied in orthopedics due to their biocompatibility, mechanical and physical properties. Here we used decyl bis phosphonate (DBP) and collagen I to modify Ti through layer by layer technique in order to improve its bioactivity. The abilities of bovine serum albumin (BSA) adsorption, the biomimetic mineralization and osteoblast behaviour on different sample surfaces were studied.X-ray photoelectron spectroscopy (XPS) and water contact angle data showed that DBP and collagen I were assembled on substrates successfully, and these data provide the evidence that DBP and collagen I were combined together through electrostatic attractions between P-O- and NH3+ rather than physical adsorption.Quartz crystal microbalance dissipation (QCM-D) was used to monitor the self-assemble process of DBP and Collagen I on titanium. The mass and viscoelastic properties of self-assembled layers were obtained using QCM-D. The DBP layer on titanium was stable in ethanol under 37℃. Excellent stability was also detected for Collagen I layer on Ti/DBP surface in PBS (pH 7.4) under 37℃for at least 3 h.Scanning electron microscope (SEM) photos and X-ray diffraction (XRD) data showed that sample of Ti/DBP/Collagen had better bioactivity in inducing HA formation than other samples tested in this investigation. The absorption of BSA solution acquired from ultraviolet spectrophotometer (UV) indicated that the sample of Ti/DBP/Collagen absorbed BSA most, followed by Ti/DBP/Collagen/DBP, Ti/DBP, and Ti.The osteoblast culture test in vitro showed there were more cells with higher activity on collagen terminated surfaces (T/P/C) than on DBP terminated surfaces (T/P,T/P/C/P) and Ti without modification. The samples after biomimetic mineralization and the BSA adsorption also showed better cell compatibility than Ti without modification. After BSA adsorption and biomimetic mineralization, the collagen terminated surfaces showed the best activity than other samples.It could be concluded that layer by layer technique using DBP and collagen I is an effective way to improve the biocompability of titanium, and the collagen terminated surfaces have the best biocompatibility.