Development of potentiometric lactate biosensor based on composite pH sensor

In this study, a micro-sized lactate sensitive biosensor based on polyvinylchloride, quinhydrone and graphite composite pH sensing platform was developed. Lactate oxidase was immobilized on the composite layer as the biorecognition element. Transformation reaction of lactate to pyruvate and hydrogen peroxide was the basis of this biosensor system. In the reaction, hydrogen peroxide undergoes to give hydronium ions into solution, and the pH sensitive membrane detects the adjunct hydronium ions potentiometrically. The surface of lactate biosensor based composite pH sensing matrice was first examined for electrochemical elucidation by using cyclic voltammetry and electrochemical impedance spectroscopy. A linear response in concentration range from 5x10 to 1x10 mol/L was obtained with a detection limit of 2x10 mol/L. The lactate biosensor developed was successfully applied for highly precise and efficient determination of lactate in food preparations. The biosensor exhibited a fast response time (10 s), had good stability, and had an extended lifetime.