Studies Of DNA Biosensors For The Detection Of Tumor Cells And Gene Mutations

Diseases including tumors and genetic diseases endanger the life quality and the lives of human beings. Achieving accurate, rapid and simple identification of these disceaces is of particular importance for the diagnosis and researches of these diseases. Up to now, some techniques have been developed for the detection of these diseases.However, these method are generally time-consuming and complicated. Several new biosensor 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 method for mutation detection is developed.The gold electrode is first modified with 1,6-Hexanedithiol. After the assembly of gold nanoparticles on the 1,6-Hexanedithiol monolayer.MutS protein was immobilized on the film of gold nanoparticles.Then, the heteroduplex DNA formed between the target DNA and the probe could interact with the immobilized protein,which enables the duplex indicator to adsorbed on the electrode surface and furnishs a measurable redox signal.This technique is successfully applied to the detection of single-base mutation in ?28 site of theβ-thalassemia gene with a detection limit of 5.66×10-13M.(3)A new biosensor based on electrochemical impedance spectroscopy(EIS) are developed for detection of glioblastoma cell through the surface immobilization of the aptamer probe onto Au electrode.The biosensor can be used to detect the target tumor cell with a detection limit of 50/mL and the linear range is of 100～50000/mL.