Electrochemical biosensor based on pyruvate oxidase immobilized AuNRs@Cu2O-NDs as electroactive probes loaded poly (diallyldimethylammonium chloride) functionalized graphene for the detection of phosphate

Abstract

A novel and sensitive electrochemical biosensor for the detection of phosphate was constructed using AuNRs@Cu2O-NDs loaded poly (diallyldimethylammonium chloride) functionalized graphene immobilized pyruvate oxidase (PyO). In this study, PDDA-Gr with good conductive ability was firstly used to increase the active site and serve as supporting substrate of biosensor. Subsequently, the AuNRs@Cu2O-NDs composite material was prepared to enhanced capability for PyO immobilization and achieved rapid electron transfer between hydrogen peroxide and Cu2O-NDs to amplify the electrical signal. Additionally, AuNRs@Cu2O-NDs loaded PDDA-Gr had good biocompatibility and yielded superior current response. The surface concentration (ΓT) of electroactive PyO on the surface of AuNRs@Cu2O-NDs/PDDA-Gr/AuE is estimated as 7.65 × 10−10 mol cm-2. Under the optimal conditions, the proposed biosensor showed a wide linearity range from 0.01 to 80 μM and a low detection limit of 0.4 nM by differential pulse voltammetry. Through a series of assessments, the biosensor exhibited satisfactory anti-interference, good stability, excellent reproducibility and successfully applied to the monitoring of phosphate content in food.