The Fabrication Of Micro/Nano-Textured Surface On Titanium And The Study Of Its Biocompatibility

It has been demonstrated that the TiO₂ nanotube arrays（TNTAs） fabricated on Ti implants surface by electrochemical anodization are beneficial to osteogenesis. However, it is dangerous for the clinical application that the TNTAs are prone to peeling off from the underlying Ti substrate due to the weak adhesion between them. It has been generally accepted that the accumulation of fluoride species results in a fluoride-rich TiO₂ layer（FRL）, which is water-soluble and believed to the main reason for the poor interfacial adhesion. Aimed at this problem, a new method is proposed in this paper that use the electrolyte mediation of Cu（NO₃）₂ by micro-arc oxidation constant current method to fabricate a micro/nano-textured surface on the Ti-based surface to replace the TiO₂ mesoporous arrays（MNT-TMAs）. The main findings from the present study are as follows:（1） The micro / nano-composite is constituted by a dense oxide layer of micron-sized and nano-aperture array, which has a thickness of about 10 μm. The structure of nano-aperture array is different from the nanotube array, whose hole wall connected to each other to form the honeycomb structure. MNT-TMAs are composed of crystal line and amorphous, the crystalline is anatase. In addition, compared with TiO₂ nanotube arrays, the coating has good film bonding strength of the substrate.（2） In this study,we use the NO₃^-alternative to the F-, which highlight the key role of NO₃^- in generating the unique structure. In the process of reaction, we can controll the aperture size of nano mesoporous by changing the concentration of NO₃^- in the electrolyte. The pore diameter are mainly distributed in between 20 to 40 nm. Cu₂₊ is not incorporated into the surface oxide layers because it cannot be further oxidized.（3） Cell toxicity experiment show that the composite coating not only has good mechanical stability but also has good biocompatibility. By adding Na₃PO₄ into the electrolyte can realize the doping of P element, thus further increase the biocompatibility of the coating. Nanopores array in the electrochemical process mediating Ti base surface is further explored by comparing the effect of SO₄²⁺, Cl- and NO₃^- ions in the electrolyte.