Benzophenoxazine-based colorimetric and fluorescent probe for highly sensitive detection of amines and food freshness

In this work, we reported a chromogenic and near infrared (NIR) region fluorogenic dual-channel probe NRB, which could visually detect gaseous amines with high sensitivity (eg. 50 and 17 ppt for methylamine (MeNH2) via naked eyes and fluorescence spectrometer respectively). It exhibited a wide fluorescent emission band extending to the NIR region with a peak at 615 nm when stimulated by the MeNH2 solution. The plausible sensing mechanism was proved by mass spectrometry, where the reaction process was based on a nucleophilic substitution between the probe and amines rather than the ester group hydrolysis. Furthermore, NRB was successfully applied to monitor the food freshness (seafood and meat food), because of its low cytotoxicity and excellent photophysical properties. It was worth mentioning that real time monitoring for food quality can be realized visually by using a 365 nm UV lamp. In addition, the probe was stable during the quality guarantee period for perishable packaged food. It was believed that the applied experiments have demonstrated the value of this probe in the practical applications for food safety.

Automated summary

In this study, a chromogenic and near infrared (NIR) region fluorogenic dual-channel probe NRB was developed for visual detection of gaseous amines. The probe exhibited a wide fluorescent emission band in the NIR region with a peak at 615 nm when stimulated by the target compound. The sensing mechanism was confirmed to be a nucleophilic substitution reaction rather than ester hydrolysis. Furthermore, the probe showed potential for real-time monitoring of food freshness and remained stable during the quality guarantee period for perishable packaged food.