Research On Design Optimization Of DNA Electrochemical Biosensor

The Internet of Things is a new information processing platform, including the system of item identification,the terminal processing system and the transmition network. The sensor technology of the system of item identification will be the key factor of the Internet of Things.DNA electrochemical biosensors have been developed rapidly in recent years, as a new kind of biosensors, which has superiority in electrode fabrication, durable years, reproduction quality, higher sensitivity, lower production cost and small size, and convenience for integration and microminiaturization. So they are of significant progress in research and application, such as clinical medical analysis, genetic engineering, mechanism of drug action, new drug selection, environmental monitoring and food engineering.This thesis aims to research on design optimization of DNA electrochemical biosensor, including how to immobilizate the probe DNA onto the working electrode, design optimization of an electrochemical DNA biosensor, application of the data fitting method and impedance measurements,nanotechnology application on electrochemical sensor for performance optimization.The electrochemical deposition of zirconia thin film on boron-doped diamond (BDD) electrode is explored, to be used as a linker to bind biomoleculars on BDD surface for biosensor applications. Two electrodeposition methods are compared, either potential cycling or chronoamperometry in ZrO2Cl2The presence of Zirconia was confirmed by XPS and EDX, and uniform and porous Zirconia film was observed by SEM. Both cyclic voltammetry and electrochemical impedance measurement indicate a partially deactivated BDD electrode, resembling a microelectrode array characteristic with small electrochemically active areas separated by inactive zirconia regions. This demonstrates that uniform and porous zirconia can be electrodeposited on BDD in a well controlled method, suitable for use in biosensor application.Developing an electrochemical DNA biosensor, using a boron-doped diamond (BDD) electrode modified with zirconia(ZrO2), the zirconia thin porous film is fabricated by cyclic voltammatic method in an aqueous electrolyte of ZrOCl2and KCL at room temperature, DNA probes are attached onto the ZrO2/BDD electrode due to the strong binding of the phosphate group of the DNA with the Zirconia film and the excellent biocompatibility of the BDD. DNA immobilization and hybridization are characterized by cyclic voltammetry and differential pulse voltammetry, using methylene blue as indicator. After the hybridization of DNA probe with the complementary DNA, the peak current of MB decrease obviously. the response current are linearly related to the concentration of the target oligonucleotide sequence.Designing a label-free detection system for DNA strands based on data fitting and impedance measurements. A single-stranded5'-PO4mer oligonucleotide (ssDNA) is immobilised via a zirconia porous film on BDD electrodes and serve as probe DNA, The sensor surface clearly distinguished between complementary and non-complementary target ssDNA. The electrode is impedimetrically characterised in the presence of the redox system ferri/ferrocyanide before and after DNA hybridisation. Impedance analysis shows that the charge transfer resistance,Ret, is increasing after DNA duplex formation, The relative change of Ret is used as sensor parameter. The sensor is easy to prepared and respond quickly.A DNA/ZrO2/MWCNT/GCE electrochemical sensor is prepared for performance optimization. The zirconia thin porous film is fabricated by cyclic voltammatic method in an aqueous electrolyte of ZrOCl2and KCl at room temperature.DNA probes are attached onto the ZrO2/MWCNT/GCE electrode due to the strong binding of the phosphate group of the DNA with the Zirconia film and the excellent active surface area of MWCNT, DNA immobilization and hybridization are characterized by cyclic voltammetry and differential pulse voltammetry,using methylene blue as indicatorhe sensor show high sensitivity and good linearity, the peak current of MB is linearly related to the concentration of the target oligonucleotide sequence in the range2.15×107to2.15x10-10mol/L with the detection limit of6.58×10-12mol/L...