Microfabricated thick-film electrochemical sensor for nucleic acid determination

Abstract

The utility of microfabricated thick-film sensors for single-use decentralized trace measurements of DNA and RNA was evaluated. Potentiometric stripping analysis (PSA) was employed to follow the oxidation of adsorbed nucleic acid species. The sensor performance is comparable to that of conventional/bulky carbon disc electrodes. Various parameters of the fabrication process and PSA operation were optimized to allow convenient monitoring of submicrograms per litre nucleic acid concentrations. The detection limits are 3, 25 and 30 µg l^–1 for tRNA, ssDNA and dsDNA, respectively. The strong adsorption was also exploited for designing single-stranded nucleic acid-modified strips. The surface-bound probes were found to hybridize selectively with their complementary ssDNA or ssRNA. The hybridization was detected directly by changes in the guanine oxidation peak of the immobilized probe. The operation of the microfabricated nucleic acid sensors was coupled with a hand-held, easy-to-use battery-operated instrument, as desired for on-site DNA diagnostics.