Studies Of Electrochemical DNA Biosensor Based On Stearic Acid And Octadecylalcohol Modified Carbon Paste Electrode

The central content of this paper was the studies of electrochemical DNA biosensors based on stearic acid or octadecylalcohol modified carbon paste electrodes.The carbon powder and the stearic acid or octadecylalcohol, which functioned as binder and chemical modification reagents as well, were mixed at suitable temperature and pressure to fabricate the basal stearic acid modified electrode (SA/CPE) or octadecylalcohol modified electrode (OA/CPE). Single-stranded DNA (ssDNA) could be immobilized covalently on the surface of SA/CPE to fabricate ssDNA modified electrode (ssDNA/SA/CPE) in the presence of 1-Ethyl-3-(3-dimethyl-aminopropyl)ca-rbodiimide(EDC) and N-Hydroxyosuccinimide(NHS). ssDNA or dsDNA could be immobilized covalently on the surface of OA/CPE to fabricate ssDNA/OA/CPE or dsDNA/OA/CPE in the presence of EDC. After being immersed into the phosphate buffer solutions containing complementary ssDNA (cDNA), ssDNA/SA/CPE and ssDNA/OA/CPE would become dsDNA/SA/CPE and dsDNA/OA/CPE respectively through recognition and hybridization. The properties of SA/CPE, ssDNA/SA/CPE, dsDNA/SA/CPE, OA/CPE, ssDNA/OA/CPE and dsDNA/OA/CPE were characterized with voltammetry by using toluidine blue or methylene blue as electro-active indicators, respectively. The results showed that: firstly, in the presence of active agent, the probes were immobilized efficiently and steadily on both of the two kinds of basal electrodes; secondly, the probes on the electrode could recognize the target DNA (cDNA) effectively; thirdly, dsDNA/SA/CPE and dsDNA/OA/CPE, which were prepared by hybridizing, would become into ssDNA/SA/CPE and ssDNA/OA/CPE after being washed with 0.5 mol/L NaOH, respectively; fourthly, the electrochemical properties of the two kinds of dsDNA/OA/CPE, which were prepared respectively by hybridizing of ssDNA immobilized on OA/CPE and immobilizing dsDNA onto...