Electrochemical labeled DNA probe for the detection of sequence-specific DNA

An electrochemical labeled DNA probe for the detection of sequence-specific DNA is discussed. The denatured calf-thymus DNA was successfully labeled w ith the electrochemical active reagent ferrocenecarboxaldehyde (FCA) by 1-e thyl-3-(3-dimethyl-aminopropyl) carbodiimide (EDC). This FCA labeled DNA pr obe is used to hybridize with the sample DNA sequence accumulated on the su rface of a graphite electrode. Only the complementary sequence (cDNA) can f orm a double-stranded DNA (dsDNA) with the FCA labeled DNA probe. The anodi c waves of the FCA bound to the double-stranded DNA (dsDNA) by differential pulse voltammetry (DPV) are used for the detection of cDNA. The anodic pea k currents (i(pa)) Of FCA are related to the concentration of cDNA sequence between 1.0x10(-8) and 5.0x10(-6) mol l(-1). The detection limit is 5x10(- 9) mol l(-1)(S/N=3). The probe showed high sensitivity and selectivity. (C) 2000 Elsevier Science B.V. All rights reserved.