Chunrong Liu

Reaction Based Fluorescent Probes for Hydrogen Sulfide

A reaction based fluorescence turn-on strategy for hydrogen sulfide (H(2)S) was developed. This strategy was based on a H(2)S-specific Michael addition-cyclization sequence. Other biological thiols such as cysteine and glutathione did not pursue the reaction and therefore did not turn on the fluorescence/consume the substrates. The probes showed good selectivity and sensitivity for hydrogen sulfide.

Fluorescent Probes Based on Nucleophilic Substitution–Cyclization for Hydrogen Sulfide Detection and Bioimaging

The design, synthesis, properties, and cell imaging applications of a series of 2-pyridyl disulfide based fluorescent probes (WSP1, WSP2, WSP3, WSP4 and WSP5) for hydrogen sulfide detection are reported. The strategy is based on the dual-nucleophilicity of hydrogen sulfide. A hydrogen sulfide mediated tandem nucleophilic substitution-cyclization reaction is used to release the fluorophores and turn on the fluorescence. The probes showed high sensitivity and selectivity for hydrogen sulfide over other reactive sulfur species, including cysteine and glutathione.

Rational Design and Bioimaging Applications of Highly Selective Fluorescence Probes for Hydrogen Polysulfides

Reactive sulfur species have received considerable attention due to their various biological functions. Among these molecules, hydrogen polysulfides (H2Sn, n > 1) are recently suggested to be the actual signaling molecules derived from hydrogen sulfide (H2S). Hydrogen polysulfides may also have their own biosynthetic pathways. The research on H2Sn is rapidly growing. However, the detection of H2Sn is still challenging. In this work we report a H2Sn-mediated benzodithiolone formation under mild conditions. Based on this reaction, specific fluorescent probes for H2Sn are prepared and evaluated. The probe DSP-3 shows good selectivity and sensitivity for H2Sn.

New fluorescent probes for sulfane sulfurs and the application in bioimaging

A sulfane sulfur mediated benzodithiolone formation was developed. Based on this reaction, two fluorescent probes (SSP1 and SSP2) for the detection of sulfane sulfur species (persulfide, polysulfide, and elemental sulfur) were prepared and evaluated. The probes showed high selectivity and sensitivity to sulfane sulfurs. Moreover, SSP2 was successfully applied for bioimaging sulfane sulfurs in living cells.

[O−NSR]TiCl3‐Catalyzed Copolymerization of Ethylene with Functionalized Olefins

Much attention has been paid to the copolymerization of ethylene with polar alkenes catalyzed by transition-metal complexes, because it provides easy and low-cost access to functional polyethylenes (PEs) with unique properties. Since the active species in olefin polymerization are metal cations in most cases, the polar alkene monomer will poison and deactivate the catalytic species under the polymerization conditions (Scheme 1). Two strategies, either the use of late-

Isotope dilution mass spectrometry for the quantification of sulfane sulfurs.

Sulfane sulfurs are one type of important reactive sulfur species. These molecules have unique reactivity that allows them to attach reversibly to other sulfur atoms and exhibit regulatory effects in diverse biological systems. Recent studies have suggested that sulfane sulfurs are involved in signal transduction processes regulated by hydrogen sulfide (H2S). Accurate and reliable measurements of sulfane sulfurs in biological samples are thus needed to reveal their production and mechanisms of actions. Herein we report a convenient and accurate method for the determination of sulfane sulfur concentrations. The method employs a triphenylphosphine derivative (P2) to capture sulfane sulfurs as a stable phosphine sulfide product, PS2. The concentration of PS2 was then determined by isotope dilution mass spectrometry, using a (13)C3-labeled phosphine sulfide, PS1, as the internal standard. The specificity and efficiency of the method were proven by model reactions. It was also applied to the measurement of sulfane sulfurs in mouse tissues including brain, kidney, lung, liver, heart, spleen, and blood.

A proline-based phosphine template for Staudinger ligation.

A proline-based phosphine template enabling a rapid Staudinger ligation of azide-containing substrates under mild conditions is reported. This reaction has a second-order rate constant of 1.12 M(-1) s(-1). It is expected that the proline-based Staudinger ligation strategy will be a useful method for bioconjugation and proline based peptide coupling.

Slow generation of hydrogen sulfide from sulfane sulfurs and NADH models.

Here we report the model studies of the reactions between NADH models (using HEH and BNAH) and sulfane sulfurs (using polysulfides). Such reactions could lead to the oxidation of NADH models and the production of hydrogen sulfide (H2S). Kinetics of the reaction between BNAH and elemental sulfur S8 were determined in ethanol and the second-order rate constant was found to be 0.074M-1min-1 (at 37°C) suggesting this is a slow process.