Formaldehyde-sensitive sensor based on recombinant formaldehyde dehydrogenase using capacitance versus voltage measurements

A new formaldchyde-selective biosensor was constructed using NAD(+)- and glutathione-dependent recombinant formaldehyde dehydrogenase as a bio-recognition element immunobilised on the surface of Si/SiO2/Si3N4 structure. Sensor's response to formaldehyde was evaluated by capacitance measurements. The calibration curves obtained for formaldehyde concentration range from 10 W to 20 mM showed a broad linear response with a sensitivity of 31 mV/decade and a detection limit about 10 mu M. It has been shown that the output signal decreases with the increase of borate buffer concentration and the best sensitivity is observed in 2.5 mM borate buffer, pH 8.40. The response or the created formaldehyde-sensitive bioscnsor has also been examined in 2.5 mM Tris-HCI buffer, and the shift to the positive bias of the C(V) curves along with the potential axis has been observed, but the sensitivity of the biosensor in this buffer is decreased dramatically to the value or 2.4 mV/decade. (c) 2006 Elsevier B.V. All rights reserved.