Sequence determination of DNA pieces using a TPD modified electrochemical biosensor

A new modifier N - [6 - (thien - 3 - yl)acetoxy] - pyrrolidine - 2,5 - dion e(TPD) and a sensitive electroactive indicator di[1 - (ferrocene - carbamoy lpropyl) - tetrahydropyrazine - 4 - (propyl carbamoyl - pyridine) -] phenaz ine (FCZ) have been synthesized. TPD is adsorbed on gold surface to immobil ize ssDNA as probe. FCZ is intercalated in dsDNA and detected by differenti al pulse voltammetry. The biosensor is based on a chemically modified elect rode, on which TPD - ssDNA is self - assembled. It is sensitive to cDNA wit h the detection limit being 8 x 10(-10) mol/L. The current signal of the bi osensor is proportional to the concentration of cDNA in the range of 2 x 10 (-8) to 1 x 10(-7) mol/L. This electrochemical biosensor has been used to d etect sequence - specific DNAs related to HIV - 1 and HBV virus.