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

Abstract

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 (i_pa) 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 between 1.0 × 10⁻⁸ and 6.0 × 10⁻⁶ mol L⁻¹. The detection limit was 2.0 × 10⁻⁹ mol L⁻¹ using 3σ (where σ is the standard deviation of blank solution, n = 11). The probe showed high sensitivity and selectivity.