| Hemocompatibility is a key property of biomaterials that come in contact with blood, and improvement of hemocompatibility is important to the development and application of biomaterials. It has been previously proved that oxygen deficient titanium oxide films possessed significantly better hemocompatibility than low temperature isotropic pryolytic carbon (LTIC) due to the n-type semiconductor nature of TiO2-x films. Therefore, two methods were performed in this work to improve the hemocompatibility of the Ti-O films based on the previous researches: (1) Ti-O films were fabricated by unbalanced reactive pulsed magnetron sputtering system and subsequently treated by hydrogen plasma, marked as "hydrogen-reduced Ti-O films"; (2) Ti-O films were fabricated in a mixture of Ar+O2+H2 ambience by unbalanced magnetron sputtering system, named as "hydrogen- introduced sputtering Ti-O-H films". For the hydrogen-reduced Ti-O films, the influence of reducing temperatures and time on the structure and properties of the Ti-O films were investigated, while various H2 flow and O2 flow were investigated for the hydrogen-introduced sputtering Ti-O-H films. The prepared films were analyzed and characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrometer (FTIR), four-point probe measurement and contact angle tester, etc. Then in vitro blood experiments were performed to evaluate the hemocompatibility of the films.In the study of hydrogen-reduced Ti-O films, the results of XRD indicated that all the hydrogen-reduced Ti-O samples had almost the same spectrum of single crystalline Rutile structure. FTIR results showed that no obvious -OH groups existed in the films. XPS spectrum displayed that oxygen deficiencies existed in the film after hydrogen plasma reduction, and the concentration of oxygen deficiencies increased while increasing the reducing time and temperature. Moreover, the hydrophilicity of the hydrogen-reduced Ti-O films decreased slightly, and the sheet resistance of the samples decreased sharply to approximately 3KΩ. In vitro platelets adhesion showed that titanium oxide films after hydrogen plasma reduction at 110℃for 15min represented the most excellent hemocompatibility. However, the hemocompatibility became worse while increasing the reducing time or temperature.In the study of hydrogen-introduced sputtering Ti-O-H films, the results showed that the H2-flow significantly influenced the composition and properties of Ti-O-H films. The thickness and stress of the films were increased as increasing H2-flow, and the crystal size was decreased slightly after introduction of H2. XPS spectra displayed that oxygen deficiencies existed in the Ti-O-H films, and the concentration of oxygen deficiencies increased while increasing H2-flow. Similar to the hydrogen-reduced Ti-O films, sheet resistance of the Ti-O-H films decreased after introduction of H2. In vitro blood evaluations displayed that the Ti-O-H films fabricated at ratio of H2 /O2 flow ranging from 0.2 to 0.3 could inhibit the denaturation of blood fibrinogen, so as to decrease the platelet adhesion and activation on the surface of films, thus improved their hemocompatibility.Based on the above researches, we come to the following conclusions: the oxygen deficiencies were created by both hydrogen plasma reduction and hydrogen- introduced sputtering. The hemocompatibility of the Ti-O film could be improved by both methods of hydrogen plasma modification. However, for the complexity of hydrogen reaction it is necessary to further investigate on the effect of hydrogen plasma modification on the hemocompatibility of the Ti-O film.
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