Curcumin-based polarity fluorescent probes: Design strategy and biological applications

Polarity is a crucial characteristic of indispensable organelles, which has been indicated to be closely related to many pathological and biological processes. Hence, a novel design strategy of curcumin-based polarity fluorescent probes was presented. Curcumin attracted much attention due to its environment-sensitivity and optical properties. We reformed the structure of curcumin by attaching a galactose moiety that was used to increase the water solubility and regulate the probe working mode. Furthermore, we also introduced a diethylamino group, which played a substantial role in adjusting the polarity specificity and sensitivity of the probes. We finally screened two polarity-specific fluorescent probes 0301 and 0302. Both probes exhibited remarkable changes in fluorescence from red to green upon increasing polarity of environment. Using 0301 in confocal imaging, we obtained a clear and exact view of lysosomal polarity in different cells, suggesting that the lysosomal polarity in normal cells is higher than that in cancer cells. Also, we use 0301 to monitor variations in lysosomal polarity in live cells induced by dimethylsulfoxide and sucrose, indicating that our probe could specifically monitor the changes of polarity in live cells to elucidate polarity-related biological processes.