Construction of a robust polarity sensitive platform and its application for tracking of lipid droplets decrease under oxidative stress in live cells

[Display omitted] •A novel fluorescent platform DN-NR was constructed for polarity detection in cells.•The fluorescence was tuned by aggregation-caused quenching (ACQ) and solvatochromism.•DN-NR exhibited highly polarity-sensitive fluorescence in both green and red channels.•DN-NR had shown lipid droplets (LDs) selectivity and the LDs evolution was tracked.•A sharp LDs numbers decrease was observed in cells under oxidative stress by DN-NR. There are many hydrophilic and hydrophobic organelles and regions in cells, which play important roles in the physiological activities of cells. In this work, we have developed a new polarity sensitive fluorescent platform (DN-NR) to detect cell polarity and lipid droplets (LDs) evolution. DN-NR is composed of the fluorophores dansyl chloride (DN) and a nile red (NR) derivative. DN-NR can detect polarity changes in both green and red detection channels. Moreover, by taking advantage of solvatochromism and the aggregation-caused fluorescence quenching (ACQ) effect of chromophores, DN-NR responds to polarity changes via emission changes in both hydrophobic and hydrophilic environments. DN-NR possesses a strong positive solvatochromism with solvent polarity change, and the response mechanism was further investigated by lifetime measurement and DFT calculation. As proved by co-staining experiments, DN-NR can effectively detect LDs in living HeLa cells, and the LDs evolution was dynamically visualized. Experimental results indicated that oxidative stress induced by H2O2 treatment leads to a sharp decrease of LDs. Therefore, DN-NR has broad prospective applications for biomedical research and diagnosis in LDs tracking and analysis.