| The main approach for the treatment of heart valve disease is valve replacement. Up to present, low temperature isotropic pyrolytic carbon (LTIC) is usually used for fabrication of mechanical heart valve due to its excellent blood-compatibility. However, its surface still causes thrombogenisity. It has been previously proved that Ti-O film possessed better blood-compatibility than LTIC. Therefore, the aim of this paper is to produce a hydrophilic Ti-O film with oxygen deficient based on the previous theory researches. Unbalanced magnetron sputtering system was adopted to deposit titanium oxide film. Lastly, high temperature annealing method was used to fabricate oxygen deficient Ti-O films. The structure, the chemical composition, the electrical property, the hydrophilicity, and the adhesion between Ti-O films and substrate were characterized by X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), four-point probe test, electrochemical testing and contact angle measurement, respectively. A series of blood-compatibility evaluations, including morphological rating, quantification assay of platelet adhesion and activation, fibrinogen activation, and clotting time measurement, were performed. Afterwards, in vivo experiment was carried out to validate the hemocompatibility of the annealed Ti-O film. Lastly, we deposited this kind film onto the valve of mechanical heart mechanical valve, and canonical in vivo experiment was performed.The results show the properties of Ti-O film fabricated by unbalanced magnetron sputtering equipment were improved by high temperature annealing treatment. XRD results proved that Ti-O was deposited on LTIC successfully. The grain size became larger and crystallization of Ti-O films was more complete after high temperature annealing in vacuum. The XPS results indicated that the concentration of "low valence" titanium Ti3+ and oxygen vacancies increased after annealing. The roughness of 900℃annealed Ti-O film increased. After annealing, the sheet resistance signigicantly reduced, and the concentration of carrier electron obviously increased.900℃annealed film presented more hydrophilic, and increased polar surface tension. The results of nano-scratch test showed the film-substrate adhesion was increased after high temperature annealing. The results of in vitro experiments showed that the 900℃annealed Ti-O films had excellent blood compatibility compared with the as-deposited Ti-O film and LTIC substrate. This was associated with a decreased number and improved morphology of adherent blood platelets after plasma contact, less fibrinogen denaturation and prolonged clotting times, all demonstrating a significant improvement of blood-compatibility. The result of in vivo experiments indicated that annealing at 900℃for Ti-O films deposited LTIC material improved its hemocompatibiliy, with the lowest thrombus.The leflets of mechanical heart valve were deposited with TiO2-x film prepared through above approach. In vivo experiment was performed. The results showed that modificated valve presented good blood-compatibility, with no thrombus. which indicated that the anticoagulation property of the valve is successfully improved. |
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