Electrically induced gas sensitive state of enzyme–metal contact in ADH-dry-layer based planar structure

Abstract

Unique gas sensitive state of the enzyme–metal contact is induced and experimentally investigated in planar thin layer sensors in air. For this, pyrroloquinolinequinone (PQQ)-dependent alcohol dehydrogenase from Gluconobacter sp. 33 (ADH) is deposited on metallic contacts and dried in ambient atmosphere. The ADH-based sensors were sensitised by a d.c. voltage in accordance with an original method. After the sensitisation, repeatable response signal to ethanol in air was detected in the electrical circuit without an external source during a number of cycles including the sensitisation and detection. It is demonstrated that the response signal is proportional to an amount of the ADH molecules at the contact. The response of the ADH layers to ethanol is increased by an increase in relative humidity (RH) of the atmosphere. The response is maximal at temperature about 304K. The gas sensitivity mechanism is related to the electron transfer from the enzyme to the metallic contact.