Biosensors for the Detection of DNA Damage by Toxicants

Abstract

Novel DNA biosensors have been designed for testing DNA damage by toxicants. In this work, we describe the development of simple accelerated tests for DNA alterations by toxicants. To facilitate rapid testing, higher concentrations of reactants were investigated than those normally found in environmental and field samples. The sensors are based on electrochemical transduction with an intercalation redox probe. The damage and conformation changes of the immobilized DNA affect the penetration of the probe molecules and the redox current profiles. These robust sensors provide single base-pair mismatch sensitivity. In this work, the Methylene Blue and Nile Blue A redox probes were evaluated for testing DNA damage caused by an herbicide atrazine. Higher sensitivity was obtained using the Nile Blue (NB) dye as the active probe. Owing to the high sensitivity of the intercalator-probe uptake to the conformational alterations of DNA double-helix, the effects of DNA incubation in atrazine solutions could be assessed. We have found that the incubation of dsDNA with atrazine results in the increased activity of NB and an increased uptake of NB by the altered dsDNA. On the basis of this and other findings, the mechanism of atrazine interactions with DNA double-helix has been elucidated.