In vivo and in vitro investigation of titanium oxide layers coated on LTI-carbon by IBED

Abstract

A layer of titanium oxide layer was coated on low temperature isotropic pyrolytic carbon (LTI-carbon), a prevailing material used for artificial heart valves' fabrication, by ion beam enhanced deposition (IBED). Glancing angle x-ray diffraction (GAXRD), X-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectroscopy (RBS), atomic force microscopy (AFM) and transmission electronic microscopy (TEM) were used to characterize the deposited titanium oxide layer. The results show that the layer is polycrystalline with TiO, Ti2O3 and TiO2 coexisting and the root-mean-square (RMS) roughness of the surface is measured to be 8.7 nm. Platelet adhesion experiments show that the adherent platelet on titanium oxide layer is about four times less than that on LTI-carbon. In vivo investigation was performed by implanting LTI-carbon and a titanium oxide layer coated LTI-carbon into the femoral artery of a dog for 4 weeks. By means of scan electron microscopy, coagulation, fibrin, deformed blood red cells and aggregation of adherent platelet were found on the surface of the uncoated LTI-carbon, whereas, nothing but a few normal-shaped blood red cells were found on the titanium oxide coated LTI-carbon. It can be concluded that titanium oxide coated LTI-carbon has a much better blood compatibility than that of the LTI-carbon.