Preparation Of Novel DNA Biosensor Based On Molecular Beacons And Strand Displacement Of Molecular Machine

Tumor cell, a cell of abnormal reproduction in the body, which is one of the most threatening diseases of the human being.Therefore, early prevention and diagnosis plays an essential role for the rehabilitation of patients in modern medicine. The accurate and sensitive recognition and detection of trace tumor biomarkers and cancer cells become a focus of attention. This thesis constructs novel biosensors with these characteristics of molecular beacon and molecular machines, including the amplification of magnetic separation, bio-barcode and isothermal circular strand displacement polymerization reaction. It with high sensitivity, good selectivity as well as being easy to miniaturization and automate has been applied in the detection of telomerase activity. The main jobs of this paper can be concluded as follows:1We designed a novle DNA biosensors with high sensitivity, good selectivity for the detection of telomerase activity, which based on signal amplification of molecular beacons and strand displacement reaction. Isothermal circular strand displacement polymerization signal amplification technology combied with stem-loop fluorescent probes composed dual circulation structure of fluorescent signal amplification. Here an Autonomous Bio-barcode DNA molecular Machine for Exponential DNA Amplification is developed, upon recognition and hybridization with the telomerase reaction, Ts primer combined with tolemerase carries out a two-cycle working mode to amplify DNA recognition events. The hairpin fluorescence probe was used as a template of signal DNA and fluorescence signal carrier. Nb.BsmI cleaves only one strand of fluorescence probe on a double stranded DNA substeate. The stems of the hairpin probes opened and restored the fluorescence signal with the separation of fluorescent and quencher, the fluorescence signals increased with the circulatory polymerization of the signal DNA and hairpin probes. Under the optimized conditions of signal amplification step, as low as2.5×10-14g mL-1telomerase activity could be detected. The biosensor has high sensitivity and excellent selectivity, the present fluorescence strategy holds great promise in the biochemical assay for the early diagnosis of cancers.2We demonstrated that the influence of fluorescence quenching of dye moleculars near glod nanoparticles, and constructs a new biosensor based on recognition of ATP and ATP aptamer. Under the optimized conditions as low as6×10-7g mL-1ATP activity could be detected. It with perfect selectivity and sensitivity applied in the detection of ATP concentration.3The study of Luminol-H2O2-Co2+flow injection chemiluminescence (FI-CL) system. The CL intensity of Luminol-H2O2-Co2+FI-CL system is affected by many factors. In this system, the detection conditions of Luminol-H2O2-Co2+FI-CL system are optimized:the concentration of Luminol solution is5.0×10-4M; the concentration of H2O2solution is1.0×10-3M and the pH of Co2+solution is4. Under the optimum conditions, the Luminol-H2O2-Co2+CL mechanism has been preliminary proposed...