Study On New Electrochemical Biosensors

Heavy metals in our environment can hardly be degradated, accumulating in human's body via various approaches, doing harm to human, even endangering when seriously. Additionally, protein and nucleic acid are the most two important macro-biomolecules, mutations of bases result in a lot of inheritant diseases, nevertheless, quantity variations of different protein in bodies image metabolism directly, serving as leading foundation of diseases diagnosis. As a result, it is significant that constructing a kind of simple, sensitive and efficient analytical measurement for protein and nucleic acid to clinical diagnosis and drug filtration. Biosensor is a kind of new detection technique, with high selectivity and sensitivity, perfect stability, low cost and fast detection in complicated system, and so on. Wherein, electrochemical detection-based bioanalysis has a great prospect for its high sensitivity, stability, low cost and apt-to-micromation. In this paper, we present several electrochemical detection techniques as follows:(1) Based on T-Hg-T configuration for detecting mercury(II), a sensitive electrochemical DNA biosensor is developed, realizing the detection of mercury(II). We observed and optimized experimental variables including the temperature of hybridization, concentrations of salt ions (Na+) as well as interference ions, which have a great influence on the sensor capability. The results showed linear dependency on mercury(II) concentration over a range from 1 nM to 5μM with a readily achievable detection limit of 1 nM.(2) We constructed an electrochemical genotyping technique based on gap ligation reaction and surface hybridization detection, actualizing the detection of human globin gene around -28 position, a known biallelic (A-G) SNP highly associated with thalassemia. In this method, after two probe strands complementary to the target probe hybrid to the target DNA, a hybrids with a gap base was formed on the mutation site. When the base complementary to the mutation one exist, two separate probes ligated after gap filling and combining by polymerase and ligase. The ligation generated to a stem-loop hairpin through intermolecular hybridization, which was captured onto the electrode surface by the immobilized probe, contributing to the adsorption of electroactive Fc onto electrode surface utmostly, leading to the redox current, and eventually we obtained highly sensitive and selective genotyping .(3) We founded a highly sensitive electrical immunosensor based on microgapped interdigitated electrode array (MGIDEA) combining enzymatic silver deposition reaction to amplify analysis signal for the detection of prostate specific antigen (PSA). From the linear sweep voltammetry (LSV) curves, the conductivity of MGIDEA could be calculated easily, and this technique was adopted to analyse PSA quantitatively. The results exhibited linearity between conductivity and the concentration of PSA in a range of 1.0 fg/ mL~1.0 ng/ mL.