An imidazole-derived polarity sensitive probe for lipid droplet target and in vivo tumor imaging.

Accurate differentiation of tumor cells from normal cells is a fundamental and critical challenge for the early diagnosis of cancer. The intrinsic low-polarity and increased numbers of lipid droplets can be utilized as potential biomarkers for tumor cells. Therefore, we synthesized and screened the polar fluorescent probe (PI-CHO), which exhibiting notable fluorescence color change and spectral shift in solvents of different polarities. PI-CHO has a high sensitivity to polarity changes in the linear range of E(30) = 37.4-63.1, with a fluorescence enhancement of more than 474-folds. Intracellular imaging experiments showed that PI-CHO has low cytotoxicity, excellent lipid droplet-targeted performance and discernibility between tumor and normal cells. Ex vivo imaging of the tumors and major organs demonstrated the great reliability and sensitive responsiveness of PI-CHO towards tumors. Moreover, the proposed probe was successfully applied to detect tumors in living mice, exhibiting the potential to become a powerful tool in early cancer diagnosis.