Multicolorimetric detection of histamine via nanozyme-mediated gold nanorod etching for food freshness monitoring

Histamine is usually regarded as an important indicator for monitoring food freshness, and the detection of histamine is crucial for ensuring food safety. Herein, a high-resolution colorimetric assay for histamine determination based on nanozyme-inhibited TMB 2 + -mediated etching of gold nanorods (AuNRs) was proposed. Hydrothermal synthesis yielded CDsEDTA@Fe³ ⁺ nanozymes with Fe³ ⁺ active sites, with Vₘ = 11.17 × 10⁻⁸ M·s⁻¹ for TMB oxidation. The strong chelation between Fe 3+ and the imidazole group on histamine modulates the catalytic activity of the carbon dot nanozymes, thereby regulating the production of the oxidative end product TMB 2+ . Upon the introduction of AuNRs as the final colorimetric substrate, a rainbow-like spectrum of 5--6 distinct color changes was observed, enabling simple and rapid visual monitoring of food freshness. The limits of detection and quantification are 13.16 μM and 18.49 μM, respectively. This strategy has been effectively applied to track the genuine spoilage of shrimp and mackerel under diverse storage situations, with a recovery rate of 94.64 %-110.65 % and an RSD (n = 3) < 6 %, showing significant promise for swift and convenient detection of histamine in food products, thereby enabling the assessment of food freshness onsite.