Near-infrared lipid droplets polarity fluorescent probe for early diagnosis of nonalcoholic fatty liver disease

[Display omitted] •TST has excellent NIR emission properties and a large Stokes shift.•TST can be used to target LDs by a wash-free procedure.•TST enables real-time monitoring of the spatial properties of LDs.•TST can be used to respond to changes in polarity under different cellular conditions.•TST has the potential to diagnose NAFLD. Nowadays, it has been proven that lipid droplets (LDs) not only maintain the fundamental cellular functions, but also play an essential role in the pathogenesis of numerous diseases. Non-alcoholic fatty liver disease (NAFLD) is among these diseases. In this work, we designed two polarity sensitive fluorescent probes TST and TSO with D-π-A-D structure by introducing different electron acceptor groups according to the low polarity of LDs. The experimental discovered that probe TST exhibited the characteristics of near-infrared emission, high selectivity towards polarity, large Stokes shift, rapid targeting ability of LDs, and robust wash-free biological imaging capability. Confocal images illustrated that probe TST has been successfully applied in monitoring LDs polarity during ferroptosis, as well as visualizing changes in LDs polarity at both tissue and organ levels in fatty liver conditions. With these exceptional properties, probe TST was anticipated to make further contributions to the field of LDs research.