Electrochemical DNA Biosensor for Detection of Aqueous Toxicants

Abstract

A simple procedure for the voltammetric detection of toxicants in aqueous samples based on their interaction with DNA at the electrode surface is reported. A disposable electrochemical DNA biosensor fabricated as a graphite-based screen-printed electrode modified by a surface layer of the salmon sperm double stranded (ds) DNA was used as a working electrode in combination with a graphite counter electrode and a silver pseudo–reference electrode. The interaction between DNA and toxicant was monitored by the change in the guanine signal using square wave voltammetric. The changes to the signal of guanine after exposure to the toxicants showed conformational change in DNA molecules. Benzene, naphthalene and antrachene derivatives were used as toxicant model compounds in this study. The effect of these toxicants on the surface-modified DNA was found to be linearly related to their concentration in solution. The comparison of the results with a toxicity assay based on the rate of NAD reduction has confirmed the applicability of the DNA biosensors as screening method for detection of the toxicants in aqueous samples.

Keywords

• electrochemical
• screen-printed electrode
• DNA biosensor
• toxicants
• genotoxic compounds