Development of benzothiazole-derived rhodamine fluorescent probes for sensitive, rapid, and reversible detection and imaging of salicylic acid in food samples and plants

Salicylic acid (SA) is a crucial molecule that is not only involved in plant immunity but also of wide interest in the ecological environment and human health. However, developing rapid, sensitive, and convenient tools for the selective detection of SA remains a significant challenge. In this study, we aimed to engineer a series of six- and five-membered benzothiazole-containing rhodamine fluorescent probes used a new synthesis method and compare probes’ fluorescence performance. Probe 1 demonstrated an excellent sensing performance for SA, including fast response (< 1 min), high selectivity, sensitivity, photostability, low detection limit (1 nM), and reversibility. As a representative fluorescence pattern, probe 1 can visualize SA in plant tissues for possible plant biology study and detected excess SA in food including grapes, bananas, and cucumbers to warn of SA-sensitized individuals. This proof-of-concept study highlights the potential application of probe 1 as a molecular tool for monitoring SA in plants and food, and it will potentially be used to detect SA in other areas of sewage detection, food industry, and cosmetics residue detection with economical, reusable, and fast response performance.