Assembly For DNA Electrochemical Biosensor

Electrochemical DNA biosensor is a novel electronic technique that combining biochemical, electrochemical, medical and electronic techniques with the advantages of being: simple, reliable, cheap, sensitive and selective for gene detection. And it can be compatible with DNA biochip. It has a broad prospect of application in the fields of clinic examination of inherited diseases and screening drug.The DNA electrochemical biosensor was prepared by self-assembling the designed ratbite fever DNA specific probe on the surface of Au electrode together with FCA(Ferrocenecarboxaldehyde) as electro-active indicator.In this paper, the condition of self-assembling, immobility of DNA and hybridization mechanism were studied. The electron-transfer capacity of the DNA modified probe was also observed. The prepared DNA electrochemical sensor was used to determine the struture and quality of complementary DNA. While the hybridization of DNA probe with complementary DNA was detected, many affective factors such as: hybridization time, hybridization temperature, washing time and the synthetic condition of signal DNA were determined, and their affection to the final detection result was discussed. Some fundamental properties such as specificity, life span, detection scale were also tested.This supplied some reference for the pre-diagnose of diseases.A novel electrochemical DNA biosensor based on methylene blue (MB) as redox indicator for DNA hybridization detection was presented. Oligo nucleotide probes with -SH at the 5 ' of DNA end were attached onto the Au surface. Hybridization was induced by exposure of Au electrode to complementary ssDNA in solution. The decreases in the peak currents of MB, an electroactive label, were observed upon hybridization of probe with the target. The cathodic peak current (Δ Ip) of MB after hybridization with the target DNA was linearly related to the value of the target DNA concentration ranging from 2.25×10^-10 to 2.25×10^-9mol/L. A detection limit of this method was 1.0×10^-10 mol/L.Colloidal Au were used to enhance immobilization amount of DNA on a gold electrode. The DNA modified electrode were electrochemically characterirzed with Co(phen)₃²⁺, a electroactive DNA-binding complex, as an indicator.An increased absorb capacity for nucleic acid incurred on the electrode is due to self-assembly ofcolloidal Au onto L-cysteine modified on gold electrode. The stability of the DNA-modified electrode was investigated. The difference between several materials was also discussed.Tomorrow biosensor will have more potential in medicine. With the development of computer technology, microfabrication technology, and biological material, biosensor will be widely used in medicine. The application of biosensor will replace the traditional methods of detection and testing and became widespread device of routine analysis and measuring.