Liquid core fluorescent organic nanoprobes: Long-term stability and highly selective lipid droplets bio-imaging

Lipid droplets (LDs) are important subcellular organelles that play a huge role in cell metabolism and growth. In this study, we synthesized two LDs fluorescent probes with benzothiadiazole (BTH) as electron acceptor and triphenylamine (TPA) as electron donor , which named as TPA-BTH1 and TPA-BTH2 , respectively. Meanwhile, we introduced long alkyl chain to the probe as a shielding group and LDs targeting enhancement group. The results showed that the two probes were too sensitive to solvents’ polarity because of the D-A structures possessed twisted intramolecular charge-transfer (TICT) effect. Furthermore, we prepared the two probes into nanoprobes by nanoprecipitation, which named as TPA-BTH1-20 and TPA-BTH2-20 , respectively. The nanoprobes also had excellent fluorescence emission abilities and biocompatibility, as well as high photostability and accurately target LDs ability, which could be successfully applied in cell fluorescence imaging experiments.