Magnetic Fe NPs as a peroxidase nanozyme for sensitive and rapid colorimetric monitoring of H2O2 and xanthine

Abstract

Given the metabolization of xanthine into uric acid, and its relevance to diseases and food safety, it is significantly desirable to propose a rapid, sensitive, and reliable strategy to monitor the expression levels of xanthine in biological liquids. Herein, a H₂O₂-responsive colorimetric sensing system was triumphantly developed for xanthine assay by combining peroxidase-mimetic magnetic Fe nanoparticles (Fe NPs) and xanthine oxidase (XOD). XOD catalyzed xanthine oxidation to H₂O₂, which combined with Fe NPs to catalyze the oxidation of the chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) to the oxidized form (oxTMB) along with the absorbance at 652 nm appearing and increasing. Therefore, a sensitive, rapid, and convenient colorimetric platform for H₂O₂ and xanthine sensing was successfully developed with a limit of detection (LOD) of 0.029 μM for H₂O₂ and 0.034 μM for xanthine. In general, the Fe NP nanozyme with high peroxidase-like activity features low-cost, high-performance, and ease of preparation, thus providing an efficient and sensitive sensing platform for blood xanthine monitoring as an alternative to traditional strategies.