NUCLEIC-ACID IMMOBILIZATION, RECOGNITION AND DETECTION AT CHRONOPOTENTIOMETRIC DNA CHIPS

Wide-scale DNA testing requires the development of fast, small, easy-t o-use biosensing devices. Various synthetic oligonucleotides and DNA h ave thus been immobilized onto microfabricated thick-film carbon trans ducers for performing several new nucleic-acid assay protocols. These include hybridization detection of nucleic acid sequences, determinati on of small molecules (drugs, pollutants) based on their collection in to the dsDNA layer or via monitoring their effect upon the intrinsic D NA oxidation signal, and direct adsorptive stripping measurements of u ltratrace levels of nucleic acids. Transduction of these DNA recogniti on processes is accomplished by a new highly sensitive constant-curren t stripping chronopotentiometric operation. Comparison to traditional electrodes indicates that the biosensing performance is not compromise d by the use of mass-producible disposable transducers. Such thick-fil m DNA biosensors have been coupled to a compact, user-friendly, hand-h eld analyzer. Applicability for the detection of sequences from M. tub erculosis and HIV-1 DNAs is illustrated. Such activity in the author's laboratory, aimed at developing DNA-coated screen-printed electrodes, is reviewed. (C) 1997 Elsevier Science Limited.