A novel dsDNA/polydiphenylamine-4-sulfonic acid electrochemical biosensor for selective detection of the toxic catechol and related DNA damage

Abstract

A novel biosensor consisting of a glassy carbon electrode (GCE) modified by a polydiphenylamine-4-sulfonic acid (PDPASA, conjugated polymer) film and double-stranded DNA (dsDNA), i.e. dsDNA/PDPASA/GCE, was researched and developed for the analysis of catechol – a potentially toxic substance for humans and the environment. The surface properties of the PDPASA film, particularly after dsDNA was immobilized on it, were characterized with the use of atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The surfaces of the novel DNA/PDPASA/GCE biosensor changed during the fabrication process and displayed high sensitivity for catechol. The oxidation potential of catechol decreased significantly and the corresponding current increased substantially as compared with the values obtained at the GCE alone and at the dsDNA/GCE. Also, with the addition of hydroquinone, two well discriminated CV peaks were obtained, and it was demonstrated that hydroquinone did not interfere with catechol. DPV analysis produced a linear catechol calibration (range: 0.750 to 8.25 × 10⁻⁶ mol L⁻¹; detection limit: 6.48 × 10⁻⁷ mol L⁻¹), and thus, various water samples were analysed successfully by this novel method. In addition, the DNA/PDPASA/GCE was used to study DNA damage in the presence of catechol with the use of the Co(phen)₃³⁺ electroactive probe. Results indicated that the potentially toxic catechol and its metabolites were all responsible for DNA damage.