Mimicking peroxidase-like activity of Co3O4-CeO2 nanosheets integrated paper-based analytical devices for detection of glucose with smartphone

Inorganic nanomaterials applied as an efficient alternative to natural enzymes, because of their low cost and high stability. Herein, we report the facile synthesis of Co3O4-CeO2 nanosheets (Co/Ce ratio is 3/1) with synergistic properties as novel biosensing platform. Significantly, this new nanocomposite possessed the properties of both Co3O4 and CeO2 and exhibited intrinsic peroxidase-like activity, which could effectively catalyze oxidation of the substrate 333',5,5'-Tetramethylbenzidine (TMB) by H2O2, which produced during oxidation of glucose by glucose-oxidase enzyme. Based on this finding, a novel paper-based analytical devices (PADs) biosensor is developed for sensitive and visualized detection of glucose. This biosensor platform is easily fabricated through equipment free method by using hydrophobic polystyrene solution. Thus, we utilized the application of Co3O4-CeO2 nanocomposite in the presence of glucose oxidase enzyme for glucose detection using the paper as measuring platform. The color change of the platform is recorded via a mobile camera and analyzed by smartphone application. This biosensor is showed to enable rapid and sensitive quantification of glucose in the concentration range of 0.005-1.5 mM with a limit of detection (LOD) of 0.21 mu M. The application of the proposed assay for colorimetric measuring of glucose in human serum samples was evaluated with satisfactory results. The good catalytic activity and low-cost make of Co3O4-CeO2 nanosheets as an effective biocatalyst developed for a wide range of potential applications in biotechnology, environmental chemistry and clinical diagnostics.