A new modifier N-[6-(thien-3-yl)acetoxy]-pyrrolidine- 2,5-dione(TPD) and a sensitive electroactive indicator di[1-(ferrocene- carbamoylporpyl)-tetrahydropyrazine-4- (propyl carbamoyl-pyridine)-] phenazine(FCZ) have been synthesized. TPD is adsorbed on glod surface to immobilize ssDNA as probe. FCZ is intercalated in dsDNA and detected by differential pulse voltammetry. The biosensor is based on a chemically modified electrode, on which TPD-ssDNA is self- assembled. It is sensitive to cDNA with the detection limit being 8× 10^-10mol/L. The current signal of the biosensor is proportional to the concentration of cDNA in the range of 2×10^-8 to 1×10^-7mol/L. This electrochemical biosensor has been used to detect sequence- specific DNAs related to HIV-1 and HBV virus.

Key words: ELECTROCHEMISTRY, AIDS, HEPATITIS VIRUS, THIOPHENOLS, IMIDE, SUCCINAMIDES, BASE SEQUENCE, VOLTAMMETRY, CHEMICAL MODIFIED ELECTRODE, BIOSENSORS