The Preparation Of TiO₂ Nanocrystalline Film And Its In Vitro Cytotoxicity Test

TiO2 nanocrystalline thin film material has the ability of excellent anticoagulant capability and guiding the growth of endothelial cells. Thus it becomes important candidate material for the surface modification of cardiovascular medical apparatus and instrμments(e.g. artificial vascular stents or artificial heart valves). Besides the test of anticoagulation property, biological materials should also make a series of testing and rating regarding the systemic toxicity and in vitro cytotoxicity before entering the clinical application.TiO2 nano-particles, with the same chemical composition and crystal structure as TiO2 nanocrystalline thin film materials, have been approved by their toxicity. Besides, the toxicity of TiO2 nano-particles is related to particle size, crystal structure, UV irradiation and other factors. However, few reports were done concerning testing and rating of systemic toxicity and in vitro cytotoxicity of TiO2 nanocrystalline thin film. Therefore, cell toxicity testing and rating of TiO2 nanocrystalline thin film could not only provide experimental and theoretical basis for the surface modification of cardiovascular implantable devices through using TiO2 nanocrystalline thin film, but also can enrich the research content involving in biological safety of nano materials, thus having important theoretical and practical application significance.For above problems, the method of high power pulsed magnetron sputtering (HPPMS), dc magnetron sputtering (DCMS) and heat treatment, vacuum annealing were applied comprehensively in the paper to explore the prepare parameters on TiO2 nanocrystalline thin film materials with different grain sizes and different crystal structures. Next, the leaching solution method in ISO 10993-5:1999 was adopted to test and rate the in vitro cytotoxicity, which mainly focused on the impact of grain size, crystal structure and leaching time on the in vitro cytotoxicity and rating of TiO2 nanocrystalline thin film material. The direct contact method of ISO 10993-5:1999 was transmitted to study the influence of ultraviolet irradiation on the in vitro cytotoxicity and rating of TiO2 nanocrystalline thin film material. Through the research, the following conclusions can be mainly obtained:1. The surface of TiO2 nanocrystalline thin film material prepared by HPPMS and DCMS is smooth, which had significant difference concerning grain sizes; after heat treatment with furnace, the grain size of the thin film was increased slightly, but numerous bubbles and cracks were produced on the thin film surface; and when annealed by vacuum annealing furnace, the oxygen overflowed and unsaturated Ti-O film structure were occurred in TiO2 nanocrystalline film;2.Grain size and crystal structure had no effect on the in vitro cytotoxicity of TiO2 nanocrystalline film. The grain size was in the scope of 10～120nm. The in vitro cytotoxicity rating of anatase and rutile TiO2 nanocrystalline film is 1, which meet the requirements of ISO 10993-5:1999 for the cytotoxicity of biomaterials.3. The leaching time, three days and sixty days respectively, had no effect on the in vitro cytotoxicity of TiO2 nano crystalline film, thus indicating that nanocrystalline thin film is a very stable structure material in a physiological environment.4. UV has no influence on the in vitro cytotoxicity of TiO2 nanocrystalline film. But it has improved the biocompatibility of TiO2 nanocrystalline film slightly.