A COF-Based Turn-On Fluorescent Sensor for Rapid Visual Detection of Histamine in Food Spoilage

Unsafe food poses a significant threat to global public health and the economy, making the early detection of food spoilage an ongoing and critical imperative. Herein, we report the design of a straightforward and highly effective fluorescence sensor for monitoring histamine (HI), a key biomarker of food deterioration, utilizing the direct interaction between the analyte and the sensor. We demonstrate that the inherently weak luminescent covalent organic framework (COF), TpPa-1, functions as a highly responsive “turn-on” luminescent switch in the presence of HI. Upon interaction with HI, the luminescence of TpPa-1 is significantly enhanced; this phenomenon is attributed to the generation of anionic N− species via the deprotonation of the N−H unit, which effectively suppresses the electron transfer pathway from the nitrogen lone pair to the COF backbone. The TpPa-1 sensor exhibits excellent sensitivity and reproducibility for HI detection. Furthermore, we developed a reusable, fluorescent COF-based film that displays a distinct, naked-eye visible color transition from red to yellow-green upon exposure to histamine, establishing a robust platform for rapid, and preliminary food quality assessment. This work presents a novel, COF-based strategy for HI detection, offering substantial significance for public health and food safety monitoring.