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 labeled with aminoferrocene (AFC) is reported. Sample ssDNA was immobilized on a chitosan modified glassy carbon electrode. A sequence-known DNA with 256 bp [obtained by polymerase chain reaction (PCR)] was successfully labeled with the electro-active reagent AFC by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide for the first time. This DNA probe labeled with AFC was applied to hybridize with a sequence-unknown DNA sample. Only the complementary sequence (cDNA) could form a double-stranded DNA (dsDNA) with the DNA probe labeled with AFC. The anodic peak currents (ipa) of the AFC bound to the dsDNA by differential pulse voltammetry were used for the determination of cDNA. The ipa of AFC was linearly related to the concentration of cDNA sequence between 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 blank solution, n = 11). The probe showed high sensitivity and selectivity.