CuCoS nanozyme-based stimulus-responsive hydrogel kit for rapid point-of-care testing of uric acid.

An efficient analysis platform composed of nanozyme-based hydrogel kit and smartphone was constructed for on-site detection of uric acid (UA) in a rapid and realiable manner. CuCoS nanoparticles (CuCoS NPs) as a peroxidase mimic were successfully prepared and the peroxidase-like activity and catalytic mechanism were studied in detail. The hydrogen peroxide (HO) stimulus-responsive nanozyme-based hydrogel kit was manufactured by integrating agarose, CuCoS NPs, and 3,3',5,5'-tetramethylbenzidine (TMB) into the cap of centrifuge tube. HO generated via UA oxidation acts as stimulus signal, which triggers the oxidation of TMB to form blue product (oxTMB) under the catalysis of CuCoS NPs, resulting in the color response of the constructed kit. The color image of the kit was captured by a smartphone built-in camera and converted into color intensity using ImageJ software, thus achieving the quantitative determination of UA. The portable kit possesses high selectivity and was used to monitor UA in human serum with satisfactory results (recovery was in the range 95.8-107.3% and RSD was not greater than 4.6%). The established sensing platform is convenient and reliable, which provides a new strategy for point-of-care testing of UA and has a broad prospect in the fields of chemical sensing and biomedical.