Rational design of AIE-based carbazole derivatives for lipid droplet-specific imaging in living cells

The visualization of lipid droplets (LDs) plays a significant role in understanding relevant diseases. Herein, a sequence of novel carbazole derivatives (L1–L9) with D-A-π-D structure have been designed and synthesized, of which the photophysical properties were systematically investigated combining with theoretical calculation. It was found that all the compounds exhibited an obvious aggregation-induced (AIE) emission behavior. In particular, compound L7 displayed the most favorable AIE property with a distinct fluorescence enhancement in ethanol/H2O mixtures. Furthermore, the living cell experiments revealed that only compound L7 could target the lipid droplets with high specificity and good biocompatibility. In brief, the lipid droplets targeting ability and the AIE characteristic render compound L7 a promising candidate for the specific visualization of lipid droplets at the cellular level.