Application of polyaniline as enzyme based biosensor

The PANI films have been synthesized electrochemically and are used as matrix for immobilization of glucose oxidase (GOD) and lactate dehydrogenase (LDH) enzymes. The temporal aspects of anion self-exchange in PANI films have been investigated. The exchange of bulkier tosylate-ferricyanide ion with Cl- ion has been monitored by photometry and electrochemical techniques. The relative changes in porosity brought about by self-exchange have been experimentally determined to be 323 and 2125/k in tosylate-exchanged and ferricyanide-exchanged polyaniline films, respectively. It is seen that the polyaniline films exhibit enhanced loading of glucose oxidase after a self-ion exchange, and, hence they can be used for the fabrication of a third generation glucose biosensor. Lactate is determined by the photometric detection of NADH formed in the reaction catalysed by LDH. Studies have been carried out with PANI as a matrix for the immobilization of LDH and its feasibility as a biosensor. The results of the photometric and amperometric measurements conducted on such LDH/PANI electrodes show a response to pyruvate concentration upto 0.45 mM, a response time of 90 s and a shelf life of about two weeks. (C) 2004 Published by Elsevier B.V.