Potentialities of hybrid materials based on RGO and AuNPs towards electroanalytical applications

A novel “in-situ” synthesis of gold nanoparticles (AuNPs) on modified reduced graphene oxide (RGO) platforms is presented. In particular, RGO functionalized with aminopyrene or pyrene carboxylic acid acts as a growing site for AuNPs with different dimensions (5, 10 and 20 nm, approximatively) and functionalizations (amine or thiol). A deep electrochemical characterization of the as prepared hybrid materials is done, paying attention to the role played by every single component by means of Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) measurements. Synergistic effects, yielding to the enhancement of the system properties, are highlighted. The key point to understand the peculiarities of these innovative materials is the charge transfer from gold nanoparticles to graphene, assisted and stimulated by the pyrene linkers. These materials are applied as electroanalytical sensors in the detection of both organic and inorganic target molecules, such as arsenic, dopamine and H2O2, with promising results. In particular, in the case of dopamine, a LOD of (3.3 ± 0.2) ppb has been reached, comparable with other electroanalytical results in the literature and in accordance with the benchmark for this molecule. For arsenic detection, appropriately adjusting the experimental conditions, the hybrid devices show increased performances, also allowing speciation between As(III) and (V). In the case of H2O2, the hybrids represent an ideal platform for developing oxidoreductase-based electrochemical biosensors displaying high electrocatalytic activity and fast electron-transfer kinetics.