| As a storage and expression carrier of biological genetic information, DNA is the basis of other compounds such as protein within the cell. Therefore, DNA analysis is of special importance in such areas of genetic inheritance, molecular diagnosis, etiology and pathology, food safety, environmental protection and forensic identification. Based on the simplicity, speediness, high sensitivity and low cost of electrochemical detection method, DNA electrochemical biosensors have been developed and become one of the most intensive and popular DNA research fields. Nowadays, it has also been successfully applied in detection of the actual DNA samples, and has a wide range of application prospect in gene detection and diagnose and other aspects.In recent years, with the development of nanotechnology, a growing number of nanomaterials have been used as the sensing material for good selectivity, high sensitivity and miniaturized DNA electrochemical biosensor with the advantages of large specific surface area, excellent photoelectromagnetism properties and flexible surface chemistry.In this work, a fast, efficient and miniaturized DNA electrochemical biosensor based on a size controllable gold-film microelectrode by the means of region-selective electroless plating method modified with nano-zirconia particles was established with p53 oligonucleoside chain as the actual gene to test its application. Mainly including the following parts:Firstly, introduction. The concept and classification of DNA biosensors are introduced. And various types of DNA biosensors are systematically expatiated. Then, the application of several types of nanomaterials in DNA biosensors is emphatically discussed. Finally, it concludes the design idea of this paper.Secondly, the DNA electrochemical biosensor based on the surface modification of nano-zirconia on the gold-film microelectrode was constructed. The gold-film microelectrodes were prepared on the polystyrene ?PS? substrate according to the photochemical localized reaction of electro less plating method, which was small and easy to carry. Then the sensing area was fixed on the size and can be adjusted by mask. The nano-ZrO2 thin films were modified by electroless plating and electrodeposition on the surface of the gold-film microelectrode, and then the probe ssDNA molecules with phosphate groups were immobilized on the surface of the modified electrode to construct the ssDNA/ZrO2/Au microelectrode of DNA biosensor, by using pairing of complementary bases to identify specific DNA sequences to achieve the target DNA analysis and detection. The surface morphology of the modified electrode was characterized by scanning electron microscopy ?SEM?. The electrochemical performance of the DNA biosensor was evaluated by cyclic voltammetry ?CV? and differential pulse voltammetry ?DPV? with MB as the redox DNA hybridization indicator, and then the standard curve was plotted and the target DNA was quantified. The experimental conditions were optimized, and the selectivity, regeneration conditions and stability of the electrode were investigated. As a result, the linear range of detection of target DNA was 1.0×10-11?-1.0×10-6 mol/L, and the detection limit was 3.83×10-12 mol/L ?S/N= 3? for the constructed ssDNA/ZrO2/Au microelectrode. And the DNA biosensor has good selectivity, repeatability and stability, both for fixed equipment testing, but also as a one-time use of portable sensors. Using the phosphorylated p53 oligonucleotides as the actual gene to verify whether the constructed DNA biosensor was suitable for the actual analysis, the results showed that the DNA electrochemical biosensors based on gold-film microelectrode modified with nano-zirconia by electrodeposition method had good performance for DNA detection and could be used for the detection of p53 oligonucleotide samples, which has potential practical application value.Thirdly, summary and prospect. |
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