摘要
Synergistic Fe 3 O 4 @TCPP-Ru nanozyme with enhanced peroxidase and oxidase-like activity. • Dual-enzyme cascade for sensitive hypoxanthine detection. • Accurate shrimp freshness monitoring versus HPLC. • Portable hydrogel-smartphone platform for hypoxanthine on-site detection. The quality and safety of aquatic products are intrinsically linked to their freshness. Hypoxanthine (HX), a primary biochemical metabolite of adenosine triphosphate, serves as a crucial biomarker for early spoilage and an indicator of aquatic food freshness. In this study, a reliable, sensitive, and convenient colorimetric sensing platform was developed for HX detection based on a dual-enzyme cascade system involving xanthine oxidase and a novel peroxidase-mimicking nanozyme, Fe 3 O 4 @TCPP-Ru, which was synthesized by modifying Fe 3 O 4 nanoparticles with tetra(4-carboxyphenyl)porphyrin (TCPP) and in situ anchoring Ru nanoclusters, resulting enhanced adsorption capacity and superior peroxidase-like activity. During detection process, HX is oxidized by XOD to produce H 2 O 2 , which triggers the Fe 3 O 4 @TCPP-Ru catalyzed oxidation of 3,3′,5,5′-tetramethylbenzidine substrate into a blue-colored product, enabling the colorimetric detection of HX. Under optimal conditions, HX can be detected in a linear range of 2.5–150 μM with a limit of detection of 1.72 μM. This method was also applied to monitor shrimp freshness, showing satisfactory recoveries (92.95%–110.69%) and good agreement with HPLC analysis. Furthermore, an integrated hydrogel-assisted colorimetric sensor was developed for smartphone-based point-of-care testing, allowing for rapid, visual, and instrument-free quantification of HX in shrimp samples stored in different temperatures and time. Our proposed Fe 3 O 4 @TCPP-Ru platform offers a promising strategy for on-site food safety monitoring. Download: Download high-res image (194KB) Download: Download full-size image
危险品化学品经营许可证（带存储）