Electrochemical Biosensors For The Detection Of Tumor And Apoptotic Cells

Development of tumors endangers the life quality and the lives of human beings. Achieving accurate, rapid and simple identification of tumor cells and its physiologic activity are of particular importances for the diagnosis and researches of these diseases. Up to now, some techniques have been developed for the detection of these diseases.However, these methods are generally time-consuming and complicated. Several new biosensors are developed in the study for the determination of the biomarker of diseases.The main work is described as follows:(1) The piezoelectric nucleic acid aptamer sensor which is based on the self-assemble membrance of mercaptor was prepared. It was used to detect the glioblastoma cell and study the behaviour of binding reaction in rmodynamics and kinetic.The results indicated that the detecting linear range of the sensor was 1.55×103～3.64×104/mL,the regression equation was△f=-41.6-1.32×10-2c, and the related coefficient was 0.997. The binding behaviour of glioblastoma cell and nucleic acid aptamer on the crystal's surface was fitted for the Langmuir adsorption equation.The association constant from this equation was 6.67×106M-1,and the reaction rate constant was 1.05×105 M-1·s-1.(2) A new biosensor based on electrochemical impedance spectroscopy (EIS) was developed for detection of glioblastoma cell through the surface immobilization of the aptamer probe onto Au electrode. In the experiment,we optimized the conditions(time,temperature,ion intensity)that influenced the capability of biosensor prominence .The biosensor can be used to detect the target tumor cell with a detection limit of 50/mL and the linear range was of 100～50000/mL.(3) A new biosensor based on immobilized receptor protein, Annexin V, to phosphatidylserine (PS) on Au was constructed via electrode self-assembly monolayer (SAM) and gold nanoparticles (AuNPs) assembly techniques. We firstly integrated tumour cells by liposomes containing PS to construct a model of early apoptotic cells.The interaction of apoptotic cells with surface immobilized Annexin V hindered the electron transfer between electrode and ferricyanide. The biosensor was applied to detect the apoptotic cells induced by 5-Fu, and the results were in good agreement with those obtained by flow cytometry.