Study Of Functionalization Membrane Modified On Titanium Surface And Interation With Calcium Phosphate Nucleation By Electrochemical Deposition

Titanium-based materials have excellent mechanical strength, chemical stability and elastic modulus which were similar to bone for tissue engineering, but it was unable to provide an inert surface properties of cells and not have good biocompatibility. Calcium phosphate (CaP) are a class of materials which clearly show osteoconductive ability for improving and accelerating their integration with bone tissue, and CaP coating has been extensively utilized to improve bioactivity and biocompatibility of implants surface. Surface properties of biological materials, such as surface topography, surface free energy, surface hydrophilicity, surface charge and other factors can affect biocompatibility of materials. So it is necessary to modify the surface of titanium-based materials by chemical surface treatment technology or coating technology.In this paper, titanium plates were grafted with octadecyl-trichlorosilane (OTS) after activated by piranha solution (H2SO4:H2O2=7:3 by volume ratio) and then the Ti-OTS was irradiated by UV light. The calcium phosphate coatings was tunablely prepared by electrochemical deposition on functionalized titanium surface with different experiment conditions. The correlative structure and morphology of CaP coatings on titanium were characterized by X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) under the preparation parameters. Its grain size under different conditions was calculated by Scherrer formula. The results indicated that the morphology of CaP coatings under different conditions were significant difference, and the grain sizes were ranged from 12.46 nm to 190.1 nm. The study demonstrated that OTS functionalized titanium surface could be a controllable preparation of uniform and orderly nano CaP coatings, which is expected to improve the biocompatibility of implant materials. And then, the influence of UV irradiation on the calcium phosphate coating on different titanium samples obtained by electrochemical deposition was also discussed. The OTS self-assembled monolayer and calcium phosphate coatings on titanium were characterized by fourier transform infrared spectroscopy (FTIR), contact angle tester, XRD and FE-SEM. The results showed that the water contact angle of Ti-OTS decreased from 109.8±2.1° to 63.4±1.8° after UV irradiation. A highly homogeneous and ordered flower-like hydroxyappatite crystals was distributed on Ti-OTS-UV, which could be expected to improve the stability of the implant material.Lastly, our objective was to determine the role of functional groups on bioactive titanium (Ti) surface by electrochemical calcium phosphate (CaP) nucleation and growth as well as bone cell adhesion and proliferation on the resulting CaP surface. Methyl group (-CH3), amino group (-NH2), epoxy group (-C(O)C) were introduced onto the bioactive Ti surface using self-assembled monolayers (SAMs) with three different silane coupling agent. The effect of the surface functional groups on the growth features of the CaP crystals were analyzed (including chemical compositions, element content, minerals morphology and crystal structure etc.). The results indicated that only CH3-terminated SAMs showed a hydrophobic surface and NH2-terminated SAMs showed a positive charge compared to others using contact angle and zeta-potential measurements. Different flower-like structures consisted of various pinpoint-like crystals were confirmed by the effect of surface functional groups, and all the CaP coatings were multicrystalline consisted of hydroxyapatite (HA) and precursors. CaP coating of CH3-terminated exhibited more excellent crystallization property as compared to coatings with -NH2 and -C(O)C groups. In vitro MC3T3-E1 cells adhesion and proliferation performed that all the CaP coatings on functionalized surfaces displayed good cell viability and have no negative effects on them. Thus, these functionalized surfaces can form homogeneous and oriented nano CaP coatings and provide a more biocompatible surface for bone regeneration and biomedical applications.