Recent advances on DNA biosensors

DNA biosensors are realised immobilising a DNA structure on a suitable tran sducer to obtain selective information. In this paper we show how the deter mination of low-molecular weight compounds with affinity for DNA was measur ed by their effect on the oxidation signal of the guanine peak of calf thym us DNA immobilised on the electrode sensor and investigated by chronopotent iometric analysis. The DNA biosensor is able to detect known intercalating and groove binding compounds. Applicability to river water samples was demo nstrated. Moreover, a piezoelectric sensor coupled to a short oligonucleotide can be used as detector of the hybridisation reaction. We show as a model the dete ction of a specific mutation in apolipoprotein E (ApoE) gene. Biotinylated 23-mer probes were immobilised on the streptavidin coated gold surface of a quartz crystal; the protein was covalently bound to the thiol /dextran modified gold surface. The device was able to distinguish differen t synthetic oligonucleotides. The hybridisation reaction was also performed using real samples of DNA extracted from human blood and amplified by Poly merase chain reaction PCR, The extension of such procedure to samples of en vironmental interest is discussed.