A wash-free AIE fluorescent probe for monitoring lipid droplets and identifying tumors.

The abnormal size and number of lipid droplets (LDs) are closely associated with a variety of diseases, including metabolic syndrome related diseases, liver disease and tumors. Therefore, it is particularly important to develop a fluorescent probe that can monitor the abnormal state of LDs. In this study, we designed and synthesized four compounds (namely TCO1, TCO2, TCN1 and TCN2) using coumarin derivatives as the fundamental building blocks. Notably, the fluorescence spectra of compounds TCO1 and TCO2 revealed distinct AIE properties in systems with different ratios of ethanol/water. Furthermore, cell imaging study of compound TCO1 exhibited negligible background fluorescence, indicating its efficacy as a washing-free fluorescent probe targeting LDs within cells. Moreover, cell imaging results for compound TCO1 showed substantial overlap with those obtained from LD commercial dye, thereby confirming its capability to specifically target LDs. Additionally, compound TCO1 was able to monitor changes in both size and quantity of LDs induced by oleic acid stimulation, as well as to discriminate between normal organs and tumours. Based on these properties, compound TCO1 developed in this study provides an effective method for detecting LD abnormalities, a novel technique for visualizing tumor sites in vitro, and also provides new insights for the detection of other related diseases.