Bimetallic Fe/Ni metal organic framework-based hypoxanthine biosensor for early monitoring of freshness changes of aquatic products

[Display omitted] •Fe7Ni3MOF was fabricated and served as a novel peroxidase-mimetic nanozyme.•A xanthine oxidase/Fe7Ni3MOF-based hypoxanthine biosensor was developed.•The biosensor produced a linear response of 3 to 70 μM for hypoxanthine detection.•The biosensor was used for early detection of freshness changes in aquatic samples. The timely detection of freshness changes of aquatic products is crucial. In this study, we have developed a reliable, cost-effective, and user-friendly method for rapidly detecting hypoxanthine using a xanthine oxidase (XOD)/nanozyme enzymatic cascade system. The nanozyme, derived from the Fe7/Ni3 metal–organic framework (Fe7Ni3MOF), exhibited good peroxidase-mimetic activity and stability. Our proposed XOD/Fe7Ni3MOF enzymatic cascade system demonstrated a linear response to hypoxanthine in the range of 3–70 μM, with a low detection limit of 1.39 μM. We also analyzed hypoxanthine in actual aquatic products, achieving spiked recoveries ranging from 90.04 % to 107.37 %. The correlation coefficient between our developed colorimetric method and the HPLC method was 0.98. Importantly, our proposed method holds several advantages over alternative techniques, particularly in terms of cost-effectiveness, precision, and speed. Consequently, this methodology shows great promise for the early detection of freshness changes in aquatic samples.