Light Enhanced Surface Charge Transfer Doping Of Ti-O Film And Hemocompatibility

Although the Ti-O film is the first choice for the coating of cardiovascular stent surface,its blood compatibility cannot achieve the desired effect of clinical application when it was related to clinical application.The key is that the surface of Ti-O film is a semiconductor material;it contains defect states such as surface states,localized states,inevitably.These non-possessory states will receive the transfer charges from fibrinogen in the blood,causing platelets are activated,then leading to clotting ultimately.In this work,the approach which is conducted to modify the energy levels and surface states of Ti-O films to improve the anti-thrombogenicity is named light enhanced surface charge transfer n-type doping.Polydopamine is the electron donor because it has the property of photo-generated charges under UV irradiation.When polydopamine is grafted on the surface of Ti-O film,its charges can transfer from polydopamine to the surface of Ti-O film.So as to achieve the purpose of regulating the surface levels and states,compositing defect states as well.Ti-O Film is deposited on the surface of Ti by unbalanced magnetron sputtering system.The chemistry composition,the structure,and the surface properties were characterized by Fourier transform infrared spectroscopy(FTIR),x-ray photoelectron spectroscopy(XPS),Atomic force microscope(AFM),X-ray diffraction(XRD),photoluminescence spectrum,and contact angle measurement respectively.Electrochemical impedance spectroscopy(EIS)and Mott-Schottky measurements were used to investigate the interfacial electrochemical behaviors.Blood-compatibility evaluations including platelet adhesion,activeated partial thromboplastin time,fibrinogen adsorption,and demolysis ratio were performed.Compared the hemocompatibility between Ti-O film of surface-charge-transfer-doping(SCTD Ti-O)and the Ti-O film of light enhance surface-charge-transfer-doping(LESCTD Ti-O).Finally,the mechanism and rule of light enhanced surface charge transfer were summed up.The main conclusions in this research are as follows:Electrochemical impedance spectroscopy(EIS)results show that LESCTD Ti-O film have greater impedance value,longer charge life,greater electron-transfer resistance.Mott-Schottky results show that the carrier concentration of space charge layer of LESCTD Ti-O increase,flat-band potential shifts negatively,the surface of LESCTD Ti-O film tends to overflow electronics.The results of blood compatibility shows that LESCTD Ti-O make the quantity of platelet adhesion reduce,the degree of activation reduce,hemolysis ratio decrease,the number of fibrinogen adsorption reduce,anticoagulant properties of LESCTD Ti-O film increase.