High-performance colorimetric sensor based on PtRu bimetallic nanozyme for xanthine analysis

The identification and quantification of xanthine are crucial for assessing the freshness and quality of food products, particularly in the seafood industry. Herein, a new approach was developed, involving the in-situ controllable growth of Pt₉₁Ru₉ nanoparticles on graphitic carbon nitride to yield Pt₉₁Ru₉@C₃N₄ catalytic materials. By integrating Pt₉₁Ru₉@C₃N₄ with the xanthine/xanthine oxidase (XOD) enzyme catalytic system, a nanozyme-enzyme tandem platform was obtained for the quantification analysis of xanthine. Under the catalytic oxidation of xanthine by XOD in the presence O₂, H₂O₂ was generated. Upon the addition of peroxidase-like activity of Pt₉₁Ru₉@C₃N₄, H₂O₂ can be decomposed into •OH and ¹O₂, which can further catalyze the oxidation of TMB to its oxidation product oxTMB with an absorption peak at 652 nm. This smartphone-assisted portable colorimetric sensor for visual monitoring xanthine with a low detection limit of 8.92 nmol L^-1, and successfully applied to detect xanthine in grass carp and serum samples.