Engineering a "dual-key-and-lock" ratiometric fluorescent nanoprobe for real-time reporting the freshness and quality...

Accurate and real-time reporting the freshness and quality of meat has far-reaching implications for safeguarding food safety and public health. Owing to the significant indicator role of H₂S in meat spoilage, we here designed a ''dual-key-and-lock'' kind of H⁺-powered H₂S-responsive ratiometric fluorescent nanoprobe BODIPY/Cy7Cl@HyNPs for precise and real-time evaluating the meat freshness. After incubation with spoilt meat, BODIPY/Cy7Cl@HyNPs was simultaneously initiated by the abnormal H⁺ and H₂S acted as "dual-keys". As a result, the fluorescence emission of BODIPY/Cy7Cl@HyNPs at ∼ 688 nm was enhanced, and the other emission at ∼ 818 nm was quenched, thereby yielding a typical H⁺-powered ratiometric fluorescence response toward H₂S in meat. In addition, we also successfully exploited BODIPY/Cy7Cl@HyNPs to achieve the real-time monitoring of the meat freshness during storage by measuring the changes of fluorescence signals and solution color.