Use of carbonic anhydrase in electrochemical biosensors for dissolved CO2

Carbon dioxide is one of the most important gases in the environment. The methods for the detection of dissolved CO2, presently in use are not satisfactory. In order to make the measurement of CO2 easier and more reliable, new electrochemical biosensors based on the enzyme carbonic anhydrase (CA) are being developed. Potentiometric and amperometric transducers were tested. The immobilization of CA on a commercially available CO2 potentiometric electrode substantially improved its response time. In the amperometric biosensor, the use of CA as the biological component, coupled to p-benzoquinone (PBQ) as a redox mediator, allowed to obtain response times 10-fold faster than in absence of the enzyme. The performance of the amperometric biosensor was optimized for mediator amount, enzyme loading, applied potential and temperature. The possibility of using highly stable and easily extractable algal CA was investigated. The stability, high activity and low cost extraction of Dunaliella salina CAs make these algal enzymes very promising for use in biosensors. (C) 1998 Elsevier Science S.A. All rights reserved.