A novel l-lactate-selective biosensor based on flavocytochrome b2 from methylotrophic yeast Hansenula polymorpha

Abstract

A novel amperometric biosensor highly selective to l-lactate has been developed using l-lactate-cytochrome c oxidoreductase (flavocytochrome b 2) isolated for the first time from thermotolerant methylotrophic yeast Hansenula polymorpha as biorecognition element. Different immobilization methods and low-molecular free-diffusing redox mediators have been tested for optimising the electrochemical communication between the immobilized enzyme and the electrode surface. Moreover, the possibility of direct electron transfer from the reduced form of FC b 2 to carbon electrodes has been evaluated. The bioanalytical properties of FC b 2-based biosensors, such as signal rise time, dynamic range, dependence of the sensor output on the pH value, the temperature and the storage stability were investigated, and the proposed biosensor demonstrated a very fast response and a high sensitivity and selectivity for l-lactate determination.