A dual-mode paper-based chip for real-time detection of histamine in fish meat via Lewis base-induced in situ fluorescence system

Since excess histamine (His) in seafood poses a significant health threat, the development of intelligent, on-site, and visual multimodal methods for detecting fish freshness has attracted widespread attention. In this study, we developed a Lewis base-induced paper-based chip coupled with smartphone RGB (Red Green Blue) recognition for the real-time colorimetric/fluorescent dual-mode detection of His in fish meat. The sensing mechanism was based on the catalytic role of His in rapidly forming a green fluorescent compound (GFC) from dopamine and 3-ethylamino-4-methylphenol. Interestingly, the introduction of 1% Tween (TW) 80 was found to significantly enhance the fluorescence signal and real-time stability of the system, achieving an exceptional detection limit of 16.67 nM for His. By immobilizing the GFC probe on Whatman 1 filter paper, a paper-based test strip for His was further developed. His quantification is achieved through RGB analysis with a smartphone, allowing visual and real-time assessment of fish meat freshness directly in the field. The developed sensor exhibits outstanding selectivity, stability, and sensitivity, and has been successfully applied to monitor His levels in fish meat samples (crucian, saury and golden pomfret) over time, providing a reliable means to prevent His poisoning. Therefore, this work presents a robust, low-cost, and user-friendly point-of-care testing platform that holds significant potential for applications in intelligent food monitoring and environmental sensing.