Electrochemical detection of sequence-specific DNA using a DNA probe labeled with aminoferrocene and chitosan modified electrode immobilized with ssDNA

The electrochemical detection of sequence-specific DNA using a DNA probe la beled with aminoferrocene (AFC) is reported. Sample ssDNA was immobilized o n a chitosan modified glassy carbon electrode. A sequence-known DNA with 25 6 bp [obtained by polymerase chain reaction (PCR)] was successfully labeled with the electro-active reagent AFC by 1-ethyl-3-(3-dimethylaminopropyl) c arbodiimide for the first time. This DNA probe labeled with AFC was applied to hybridize with a sequence-unknown DNA sample. Only the complementary se quence (cDNA) could form a double-stranded DNA (dsDNA) with the DNA probe l abeled with AFC. The anodic peak currents of the AFC bound to the dsDNA by differential pulse voltammetry were used for the determination of cDNA. The i(pa) of AFC was linearly related to the concentration of cDNA sequence be tween 1.0 x 10(-8) and 6.0 x 10(-6) mol L-1. The detection limit was 2.0 x 10(-9) mol L-1 using 3 sigma (where sigma is the standard deviation of blan k solution. n = 11). The probe showed high sensitivity and selectivity.