Cholesterol biosensor based on cholesterol esterase, cholesterol oxidase and peroxidase immobilized onto conducting polyaniline films

Cholesterol oxidase, cholesterol esterase and peroxidase have been co-immobilized onto electrochemically prepared polyaniline films. These polyaniline-enzyme films characterized using spectroscopic techniques, have been used to fabricate a cholesterol biosensor. This polyaniline-based cholesterol biosensor has a response time of about 240 s, an apparent K-m value as 75 mg dl(-1) and can be used to estimate cholesterol concentration up to 500 mg dl(-1). These polyaniline/cholesterol oxidase/cholesterol esterase films have a detection limit of 25 mg dl(-1) with sensitivity of 0.042 mu A mg dl(-1). The enzyme films were found to be thermally stable up to 48 degrees C and have a shelf-life of about 6 weeks when stored at 4 degrees C. The values of the activation energy before and after the critical temperature were found to be 191 and 95.5 kj mol(-1), respectively. (c) 2005 Elsevier B.V. All rights reserved.