Laccase Polyphenolic Biosensor Supported on MnO2@GNP Decorated SPCE: Preparation, Characterization, and Analytical Application

Abstract

Based on graphene nanoplatelets capability to build block composites, as well as well-known electrochemical characteristic of the manganese oxide materials, in the present research, a nanocomposite, formed from graphene nanoplatelets (GNP) and manganese(IV)-oxide (MnO2) nanoparticles, has been proposed as a novel and convenient support for enzyme immobilization. Performance of screen printed carbon electrodes (SPCEs) was significantly improved after their modification with GNP@MnO2 (SPCE/GNP@MnO2). The polyphenolic index biosensor was prepared by applying the drop coating technique using laccase and Nafion®. Developed biosensor shows a fast and reliable amperometric response toward caffeic acid, as a model compound, at operating potential of +0.40 V (vs Ag/AgCl), with a wide linear range and detection limit of 1.9 μmol l−1. Developed procedure was successfully applied for the determination of polyphenolic indexes in wine samples. Recovery tests indicate excellent accuracy and precision of the method, concluding that the biosensor can offer a fast, accurate, reliable and precise determination of the polyphenolic index. More importantly, our results suggest a great potential for the application in real samples.