Individual and successive detection of H2S and HClO in living cells and zebrafish by a dual-channel fluorescent probe with longer emission wavelength.

Reactive oxygen species (ROS) and reactive sulfur species (RSS) participate in many physiological activities and help maintaining the redox homeostasis in biological system. The complicated intrinsic connection between specific ROS/RSS needs to be further explored. Herein, a novel fluorescent probe (MB-NAP-N3) with longer emission wavelength has been rationally designed and synthesized based on the conjugation of the methylene blue moiety and the naphthalimide moiety for the detection of hypochlorous acid (HClO) and hydrogen sulfide (H2S). The dual-signal probe exhibits rapid turn-on fluorescence responses for individual and successive detection of H2S and HClO in green and red channels, respectively. Owning to its advantages such as fast response, good selectivity and high sensitivity, the probe was successfully applied to detect endogenous and exogenous HClO/H2S in living cells. Furthermore, the outstanding luminescence performance makes it suitable for the visualization of the in vivo interaction between the two analytes in zebrafish.

A novel AIEgen-based probe for detecting cysteine in lipid droplets.

A smart fluorescent probe DPAS-Cys has been rationally designed based on a typical AIEgen DPAS and an acrylate moiety. The probe DPAS-Cys not only can be used for the detection of cysteine (Cys) selectively with large Stokes shift (200 nm) and relatively low detection limit (2.4 µM), but also shows lipid droplets (LDs) targeting property. The response mechanism for Cys was carefully verified. Importantly, due to the aggregation-induced emission characteristic, the introduction of considerable percentage of traditional organic solvent is avoidable, which makes it suitable for bioimaging in physiological systems. In addition, the confocal fluorescence imaging demonstrates that DPAS-Cys is able to detect Cys in LDs of different cell lines with universality. Our study opens a new avenue to understand the importance of LDs in biosystem, for which the gap between the essential biothiol Cys and the energy storage organelle LDs was bridged for the first time.