Multifunctional pyrazoline based AIEgens: real-time tracking and specific protein "fishing" of lipid droplets

Despite the rapid development of organic fluorescent probes for bioimaging and biosensing applications, construction of advanced probes with multiple biological functions by precisely integrating different functionalized elements into a single molecule has rarely been reported. In this contribution, a series of multifunctional pyrazoline based fluorescent probes (Pyr-n, n = 1-5) were designed and synthesized by introducing different aromatic moieties into the pyrazoline core. All Pyr probes exhibited the aggregation-induced emission effect. Thanks to the excellent biocompatibility and suitable lipophilicity, the Pyr probes can stain the lipid droplets (LDs) in living cells with high specificity as well as track the lipid metabolism in Zebrafish embryos. The protonation-deprotonation capability of the diethylamino group enables Pyr-5 to reversibly migrate between LDs and mitochondria, and real-time monitor the intracellular pH change in dual-color mode. The mild reaction between the pentafluorophenyl unit and thiol group makes Pyr probes the ideal probes to "fish out" the proteins associated with LDs in living cells.