Electrochemical DNA biosensor for environmental monitoring

A disposable electrochemical DNA biosensor for the determination of toxic aromatic amines has been developed. The device relies on the intercalative or electrostatic collection of aromatic amines onto an immobilized dsDNA or ssDNA layer (obtained from several sources), followed by a chronopotentiometric analysis. The anodic signal of the guanine bases of DNA coated screen printed electrodes (SPEs) is strongly influenced by structural or conformational modifications of the DNA layer accrued from DNA-analyte association. So the variation in the oxidative signal of guanine is taken as an index of the molecular recognition. When the analyte is electroactive, its oxidation peak gives an additional information; in fact interesting correlation have been found between the amount of analyte trapped on the electrode and the guanine peak variation. Submicromolar detection limits have been obtained for molecules with more than two aromatic rings after a 2min accumulation. The biosensor has also been tested on wastewater real samples; the comparison with results of classical genotoxicity tests has confirmed the applicability of the method for real samples.