Electrochemical DNA biosensor as a screening tool for the detection of toxicants in water and wastewater samples.

Applications of a disposable electrochemical DNA biosensor to standard solutions and to real samples are reported. The DNA biosensor is assembled by immobilising the double stranded calf thymus DNA on the surface of a disposable carbon screen-printed electrode. The immobilised ds-DNA interacts with the sample for 2 min; then is washed and immersed in a clean buffer where the analytical signal (the oxidation peak area of the guanine base) is obtained by a square-wave voltammetric scan. The results were compared with some currently used toxicity tests and in particular with a commercial luminescent bacteria test, Toxalert(R)100.