Functionalized bimetallic IrPt alloy nanoparticles: Multi-enzyme mimics for colorimetric and fluorometric detection of hydrogen peroxide and glucose

Nanomaterials that demonstrate multi-enzyme activities have increasingly gained interest due to their potential applications in point-of-care diagnostics. In the present work, polyvinylpyrrolidone-functionalized bimetallic IrPt alloy nanostructures (PVP/IrPt ANs) exhibited excellent peroxidase-, oxidase-, and catalase-like activities were synthesized with a reflux-assisted one-pot wet chemical process. The use of PVP as stabilizer and surfactant during the synthesis produced monodisperse nanoparticles (NPs) with average diameter of 4.1 nm. The PVP/IrPt ANs catalyze the oxidation of H2O2, TMB, and amplex red through the peroxidase and oxidase biomimetic activities. The kinetic parameters of PVP/IrPt ANs were measured to demonstrate their enhanced enzyme-like behavior relative to previously reported bimetallic nanozymes. The oxidase- and peroxidase-like activities of PVP/IrPt ANs were employed for efficient colorimetric and fluorescent detection of H2O2 concentrations. Moreover, the multi-enzyme activity of PVP/IrPt ANs was coupled with the glucose oxidase activity to fabricate colorimetric and fluorometric glucose sensors. The colorimetric glucose sensor revealed a broad detection range of 2.5 µM – 1.5 mM, while the fluorometric sensor showed excellent limit of detection (LOD) of 177.5 nM. In comparison, colorimetric detection can be easily visualized by the naked eye, demonstrate good selectivity, and recovery of glucose from spiked biological and food samples.