Colorimetric determination of glucose in solution and via the use of a paper strip by exploiting the peroxidase and oxidase mimicking activity of bimetallic Cu-Pd nanoparticles deposited on reduced graphene oxide, graphitic carbon nitride, or MoS2 nanosheets.

This work describes the preparation of bimetallic Cu-Pd nanoparticles (NPs) on supports like reduced graphene oxide (rGO), graphitic carbon nitride (g-C3N4) and MoS2 sheets with a size of <10 nm. rGO is found to be the best support for synthesizing Cu-Pd NPs with controlled shape, size and oxidation state. The Cu-Pd/rGO nanocomposite also demonstrated the best peroxidase and oxidase mimicking activity compared to Cu-Pd/g-C3N4 and Cu-Pd/MoS2 nanocomposites. The peroxidase mimicking activity of Cu-Pd/rGO was investigated in more detail, and a glucose oxidase (GOx) based glucose sensor was constructed that is based on the enzymatic formation of H2O2 and the Cu-Pd NPs-assisted oxidation of tetramethylbenzidine by H2O2 to give a blue-green coloration with absorption maxima at 652 nm. The assay has a 0.29 μM detection limit and a detection range that extends from 0.2 to 50 μM. The method was applied to the determination of glucose in diluted serum samples, and results compared well to those acquired with a clinical analyzer. The method also was applied in a colorimetric paper-based test stripe that can detect glucose within 10 min. Graphical abstract Schematic representation of a sensitive colorimetric glucose assay based on bimetallic Cu-Pd nanoparticles supported on 2D nanosheets, and construction of a paper based device for rapid glucose detection.