Co-immobilization of lactate oxidase and lactate dehydrogenase on conducting polyaniline films

Lactate oxidase (LOD) and lactate dehydrogenase (LDH) have been co-immobilized on electrochemically prepared polyaniline (PANI) films by physical adsorption. Regeneration of L-lactate by substrate recycling is shown to provide an amplification of the sensor response. The LOD/LDH immobilized electrodes show a linearity from 0.1 to 1 mM of lactate and stability of about 3 weeks at 4-10 degrees C. These PANI/LOD-LDH enzyme electrodes have a detection limit of 5 x 10(-5) M implying that these can be used for the estimation of L-lactate in cells and fermentation. A comparison of the results obtained with the PANI electrodes immobilized with either LOD or LDH, indicate that co-immobilization provides the possibility to detect L-lactate at lower concentrations. (C)2000 Elsevier Science B.V. All rights reserved.