Portable Hydrogel Kits Made with Bimetallic Nanozymes for Point-of-Care Testing of Perfluorooctanesulfonate

Perfluorooctanesulfonate (PFOS), an emerging organic contaminant, necessitates robust on-site detection strategies to safeguard human health and ecological balance. This study introduces a novel point-of-care testing (POCT) platform, combining a hydrogel kit with nanozymes and smartphone technology, for the highly sensitive detection of PFOS. The strategy utilizes copper-substituted cobalt-based Prussian blue analogue nanoboxes (CuCo-PBA NBs), which exhibit intricate hollow structures and remarkable peroxidase-like catalytic activity, efficiently catalyzing the oxidation of chromogenic substrates with hydrogen peroxide (H₂O₂). Density functional theory calculations elucidate the adsorption dynamics of H₂O₂ on CuCo-PBA NBs, identifying the factors that improve the catalytic efficiency. The colorimetric POCT platform, integrating the hydrogel kit with a smartphone interface, demonstrates practical utility and achieves a detection limit of 1.43 × 10^-8 mol L^-1 for PFOS. This research not only presents a new nanozyme design for PFOS detection in diverse matrices, such as lake water, whole blood, urine, and milk, but also paves the way for developing a portable and efficient POCT platform for a variety of emerging contaminants.