Key Plasma Protein Behavior At Titanium Oxide Interface And Its Correlation With Coagulation

Oxygen deficient titanium oxide films possessed significantly better hemocompatibility than low temperature isotropic pryolytic carbon (LTIC) due to the n-type semiconductor nature. Based on the former experiments, high temperature annealing would furtherly improve the hemocompatibility of Ti-O flms. The study of in situ interaction between materials and the coagulation system(plasma protein,platelets) is so inadequate,anti-coagulation theory in the molecular level hasn’t been obtained. However the exact anti-coagulation mechanism is no clear.Based on the previous research, unbalanced magnetron sputtering system and high temperature annealing method were used to fabricate Ti-O film with different temperature annealing process, and study its hemocompatibility including the method of Enzyme-Linked Immunosorbnent Assay (ELISA) to measure the amount of adsorption and y chain exposure of fibrinogen. In this research,800℃annealed Ti-O film exhibited outstanding hemocompatibility due to its least amount of y chain exposure of fibrinogen which would be concluded as a result of the least adsorption of fibrinogen.Different tempreture annealed TiO2powder samples were used to study the adsorption behavior of fibrinogen on the surface. The properties of the films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Zeta potential Test, surface area measurement (BET). Flow cytometry was used to carry out the activation degree of platelets contacted with TiO2powder samples. Adsorption and desorption of adsorbed bovine plasma fibrinogen (FBG) were determined by Bradford method, and the change of secondary structure upon FBG adsorption was carried out by Fourier transform infrared spectroscopy (FTIR).According to the result,800℃annealing process enabled the crystal structure to change from anatase to rutile with less total surface area and more acid which would produce more negative charge under a physiological pH condition. The result of flow cytometry convinced800℃annealed TiO2powder would cause less platetets activation. Unannealed and600℃annealed TiO2powder samples both have a larger FBG adsorption than the800℃samples due to their larger total surface area, whereas800℃sample had the largest FBG adsorption on a unit area probably because it has more negative charges to interact with the positive charges of aC terminal of FBG through the electrostatic interaction. It could be speculated that the orientation of FBG partly changed from side-on to end-on, and this end-on orientation would lead to a larger amount of desorption because of it less stability. FTIR showed once FBG adsorbed on the TiO2powder samples, α-helix decreased, β-turn increased with the appearance of side chain which is a strong evidence of aC terminal involved in the electrostatic interaction.Based on the above results, it could be infered the surface charge and area would be important reasons in the asorption behavior of Ti-O film.