Electrochemical DNA biosensor for the determination of benzo[a]pyrene-DNA adducts

The metabolites of the environmental pollutant, benzo[a]pyrene (BaP) are ca rcinogenic and mutagenic agents. Thus, the determination of additional prod ucts (adducts) of the interaction between DNA and BaP, attracts great inter est in cancer research. In this study, the determination of interaction between BaP and calf thymus double-stranded DNA (dsDNA) was performed by using differential pulse volt ammetry (DPV) and constant current chronopotentiometric stripping analysis (PSA) in connection with carbon paste electrode (CPE) or glassy carbon elec trode (GCE). As a result of interaction of BaP with dsDNA, the signal obtai ned from the oxidation of guanine decreased and a new adduct signal at a mo re positive potential appeared. This new peak is attributed to the formatio n of an adduct from the interaction of guanine with BaP The chemically prep ared anti-7,8,9,10-tetrahydrobenzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE) ad duct by using iodine oxidation was analyzed and the electrochemical signal of the adduct was observed. When the dsDNA modified GCE was immersed into v arious concentrations of BaP solution, the oxidation peak of guanine decrea sed and the adduct peak increased with the increasing BaP concentration. Th e partition coefficient was also obtained from the peak of BaP with dsDNA. The results revealed that the formation of adducts could be determined by u sing electrochemical DNA biosensors, which are fast, simple and cost-effect ive devices. Furthermore, this study promises that the analysis of other im portant adducts would benefit from the introduction of electrochemical meth ods. (C) 2001 Elsevier Science B.V. All rights reserved.