Direct detection of formaldehyde in air by a novel NAD super(+)- and glutathione-independent formaldehyde dehydrogenase-based biosensor

• Published in: Talanta (Oxford) Vol. 75; no. 3; pp. 786 - 791
• Main Authors: Achmann, S, Hermann, M, Hilbrig, F, Jerome, V, Haemmerle, M, Freitag, R, Moos, R
• Format: Journal Article
• Language: English
• Published: 01.05.2008
• Subjects: Hyphomicrobium
• ISSN: 0039-9140
• DOI: 10.1016/j.talanta.2007.12.015

An amperometric enzyme-based sensor-system for the direct detection of formaldehyde in air is under investigation. The biosensor is based on a native bacterial NAD super(+)- and glutathione-independent formaldehyde dehydrogenase as biorecognition element. The enzyme was isolated from Hyphomicrobium zavarzinii strain ZV 580, grown on methylamine hydrochloride in a fed-batch process. The sensor depends on the enzymatic conversion of the analyte to formic acid. Released electrons are detected in an amperometric measurement at 0.2 V vs. Ag/AgCl reference electrode by means of a redox-mediator. To optimize the sensing device, Ca super(2+) and pyrroloquinoline quinone (PQQ) were added to the buffer solution as reconstitutional substances. At this stage, the sensor shows linear response in the tested ppm-range with a sensitivity of 0.39 kA/ppm. The signal is highly reproducible with respect to sensitivity and base line signal. Reproducibility of sensitivity is more than 90% within the same bacterial batch and even when enzyme of different bacterial batches is used.