A dual-emission fluorescent ratiometric probe based on bimetallic lanthanide complex interacted in nanoclay for monitoring of food spoilage

Owing to increasing food-safety issues, food insecurity is an enormous threat to human health and the economy. Therefore, it is necessary to explore efficient and early food spoilage detection. Herein, we develop a ratiometric fluorescent probe based on the embedding of bimetallic Ln3+ (Eu3+ and Tb3+) complex intercalated in nanoclay, which can monitor the real-time visual surveillance freshness of food. The fluorescent probe exhibits a dualemission responsive to biogenic amine along with a significant decrease in Tb3+ emission intensity and an increase in Eu3+ emission intensity, enabling an obviously distinguishable color transition from yellow to orange to rose red clearly discerned by naked eyes. The probe shows an outstanding response and excellent sensitivity which has a low limit of detection (LOD=0.137 mg L-1) for target biogenic amines (histamine) in the range (4-22 mg L-1). Besides, we use the gel to inspect the change in the freshness of raw fish in a hermetic space. It is proved that the nanocomposite can be applied to the on-site inspection of the food freshness. This work provides a novel direction for the evolution of fluorescent nano-clay based lanthanide complexes as a new platform for application in food surveillance.