A novel fluorescent probe with ACQ-AIE conversion by alkyl chain engineering for simultaneous visualization of lipid droplets and lysosomes

The AIE bio-probes have attracted extensive attention because of their good brightness, long-term in situ retention ability, photostability and low cytotoxicity. Recently, the transformation of ACQ to AIE has become very popular, which is very important for the further development of AIE probes. Herein, a series of novel dyes (NR-Lyso-Ⅰ, NR-Lyso-Ⅱ, NR-Lyso-III, NR-Lyso-IV) were designed and synthesized. It was found that alkylation of 4-aminonaphthalimide could achieve the transformation of the dye from ACQ to AIE effect due to the growth of carbon chain. Moreover, the AIE probe NR-Lyso-IV exhibited dual-state emission (DSE) and large Stokes shift (＞100 nm), excellent selectivity, photostability, and low cytotoxicity, which was able to simultaneous visualize the lipid droplets (LDs) and lysosomes of HeLa cells and zebrafish.