Fabrication And Characterization Of Multistage Micro And Nano-structure And Calcium Phosphate Coating On Titanium Surface

Titanium and alloys are widely used in artificial bone, artificial joints, vascular stent and other Biological implant metal materials for its high strength, corrosion resistance, close to the bone elastic modulus in numerous medical metal materials, biocompatibility and other advantages.However, titanium and alloys are generally bioinert and not conducive to direct bonding after implanting in vivo. The low bonding strength between them leads to immune response and titanium implants loose or even failure. Studies have shown that titanium surface morphology, especially micro and nanostructures can effectively simulate the micro and nano environment in vivo, and promote protein adsorption, cell adhesion, proliferation and differentiation. Therefore, titanium surface modification, fabrication of micro and nanostructures can effectively improve the speed of bone tissue healing, improve osseointegration and promote new bone formation. As a biological ceramic material, apatite is the main inorganic component of the bone, promote bone tissue repair. But it have poor mechanical properties. To combine with the advantages of both, titanium surface deposite calcium phosphate coatings, fabricate micro and nanostructures, not only can improve the biocompatibility of the implant and enhance the bonding between the implant and bone, but also can make up biological ceramics’defects in mechanics.Firstly, Using different concentrations of phytic acid under hydrothermal treatment to fabricating multi-level micro and nano structures,and then deposited calcium phosphate on it with biomineralization method.the samples were characterization by scanning electron microscope (SEM), x-ray diffraction (XRD), energy dispersive x-ray analysis (EDX). The results showed that:(1) different concentrations of phytic acid under hydrothermal treament obtained different titanium surface morphology and composition, when the phytic acid concentration was 5 v/v%, the surface generated the TiO2 about 1-3μm, and when the concentration of phytic acid was 7.5 v/v%, the surface formed Micro-Nano combination groove-shaped structure, when the phytic acid concentration of 10 v/v%, the surface formed the petaloid structure by the lamellar structure self-assemble, the composition of that is Ti (HPO4)2 and Ti (HPO4) 2·H2O. (2) the three different micro and nanostructure under hydrothermal treatment are given pre-calcified with pulling dipping method, then soaked into oversaturated calcium phosphate solution to deposite calcium phosphate coating.Secondly, with the method of hydrothermal alkali treatment, fabricating titanium nanowire on titanium surface, then in-situ deposited calcium phosphate on it through the second hydrothermal treatment, and it did not cover the original titanium nanowire.The results showed that:(1) hydrothermal alkali treatment obtained uniform crack-free titanium nanowire at the length of 4-8μm, the width of about 50-200 nm;(2) through the second hydrothermal treatment, the small molecule template H6L regulating calcium phosphate crystal growth, in-situ deposition of calcium phosphate on titanium nanowire, constructed multi-level micro and nanostructures on titanium surfaces.Finally, protein adsorption and osteoblast cultures experiments proved that titanium surface with micro and nano structuresare conducive to bovine serum albumin adsorption;Titanium surface with in-situ deposition of calcium phosphate to build multi-level micro and nanostructure is more conducive to osteoblast proliferation.