A Facile Preparation of Reduced Graphene Oxide Capped AuAg Bimetallic Nanoparticles: A Selective Nanozyme for Glutathione Detection

Abstract Over the last decade, artificial enzymes (nanozymes) have undergone substantial development in the field of sensing. In this study, Au−Ag bimetallic nanoparticles (NPs) decorated on reduced graphene oxide sheets (AuAg‐rGO) nanocomposite has been developed as a novel colorimetric probe based on the peroxidase imitating activity of the nanozyme. AuAg‐rGO nanocomposite proved to feature an intrinsic peroxidase mimic activity, facilitating the oxidation of a peroxidase substrate like 3,3’,5,5’‐tetramethylbenzidine (TMB) with high efficiency to oxidised TMB (blue coloured product) with the aid of hydrogen peroxide (H 2 O 2 ). The characteristic Michaelis‐Menten kinetics study allowed the establishment of the catalytic performance of AuAg‐rGO as an artificial enzyme. Glutathione (GSH) displays inhibiting effect on the oxidation of the peroxidase substrate, TMB. Therefore, AuAg‐rGO nanozyme was applied for detection of GSH and exhibited exceptional selectivity and sensitivity with a low limit of detection (LOD) of 38 nM within the 0–200 μM concentration range. The artificial nanozyme system reported here is simple, convenient, and straightforward for colorimetric sensing of GSH.