Structure-regulated mitochondrial-targeted fluorescent probe for sensing and imaging SO2in vivo

SO2 and its derivatives play an important role in the antioxidation and anticorrosion of food and medicine. In biological systems, abnormal levels of SO2 lead to the occurrence of many biological diseases. Hence, the development of suitable tools for monitoring SO2 in mitochondria is beneficial for studying the biological effect of SO2 in subcellular organelles. In this research, DHX-1 and DHX-2 are fluorescent probes designed on the basis of dihydroxanthene skeletons. Importantly, DHX-1 (650 nm) and DHX-2 (748 nm) show near-infrared fluorescence response toward endogenous and exogenous SO2, which showed advantages of great selectivity, good sensitivity and low cytotoxicity, and the detection limit is 5.6 μM and 4.08 μM of SO2, respectively. Moreover, DHX-1 and DHX-2 realized SO2 sensing in HeLa cells and zebrafish. Moreover, cell imaging demonstrated that DHX-2 with a thiazole salt structure possesses good mitochondria-targeting ability. Additionally, DHX-2 was perfectly achieved by in situ imaging of SO2 in mice.

Dual-Responsive Benzo-Hemicyanine-Based Fluorescent Probe for Detection of Cyanide and Hydrogen Sulfide: Real-Time Application in Identification of Food Spoilage

Colorimetric and fluorescent probes have received a lot of attention for detecting lethal analytes in realistic systems and in living things. Herein, a dual-approachable Benzo-hemicyaninebased red-emitting fluorescent probe PBiSMe, for distinct and instantaneous detection of CN^- and HS^- was synthesized. The PBiSMe emitted red fluorescence (570 nm) can switch to turn-off (570 nm) and blue fluorescence (465 nm) in response to CN^- and HS^-, respectively. Other nucleophilic reagents, such as reactive sulfur species (RSS) and anions, have no contact or interference with the probe; instead, a unique approach is undertaken to exclusively interact with CN^- and HS^- over a wide pH range. The measured detection limits for CN^- (0.43 μM) and HS^- (0.22 μM) ions are lower than the World Health Organization's (WHO) recommended levels in drinking water. We confirmed 1:1 stoichiometry ratio using Job's plot and observed good quantum yield for both analytes. The probe-coated paper strips were used to detect the H₂S gas produced by food spoilage (such as eggs, raw meat, and fish) via an eye-catching visual response. Moreover, fluorescence bioimaging studies of living cells was done to confirm the probe's potential by monitoring the presence of CN^- and HS^- in a living system.

A near-infrared emitted fluorescence probe for the detection of biosulfite in live zebrafish, mouse and real food samples

Bisulfite (HSO₃^-) has been widely used as an important food additive in daily life. Furthermore, a normal amount of HSO₃^- plays a significant role in biological systems. However, excessive intake of HSO₃^- will lead to a variety of diseases. Therefore, it is of great significance to develop an efficient fluorescent probe that can be used for detection of HSO₃^- in biological systems and food samples. In this work, a near-infrared (NIR) emitted fluorescent probe (SZY) based on hemicyanine dye was successfully synthesized and applied to detect HSO₃^- in several food samples and live animals. The proposed nucleophilic addition sensing mechanism of SZY towards HSO₃^- has been confirmed by ¹H NMR titration, high resolution mass spectrometry (HR-MS) and density functional theory (DFT) theoretical computation. The HSO₃^--induced nucleophilic reaction with α,β-unsaturated C=C binding of SZY results in the dramatic decline of the UV-vis absorption and remarkable quenching of the fluorescence emission. SZY features the advantages of near infrared emission (centered at 720 nm), high water solubility (in 98% aqueous solution), fast response time (50 s), large Stokes shift (244 nm) and low cytotoxicity. The probe SZY was successfully applied to image of HSO₃^- in live nude mouse and adult zebrafish. Semi-quantitatively analyzing the HSO₃^- level by "naked eye" in several food samples including canned fruit, white wine, white sugar and jasmine tea drinks has been realized by the colorimetric method.