Thiol Derivatives Research Articles

Hierarchy in Au Nanocrystal Ordering in Supracrystals: III. Competition between van der Waals and Dynamic Processes

Au nanocrystals coated with thiol derivatives of varying chain sizes ranging from C12 to C16 were produced; two different size nanocrystals have been synthesized (5 and 7 nm in diameter) for each coating agent. All of those specimens are characterized by a low size distribution (below 7%). Those Au nanocrystals were used as building blocks to grow larger self-assembled crystalline structures or supracrystals. These crystalline growths were carried out by slow and controlled solvent evaporation at different temperatures and under non-null partial solvent vapor pressure (Pt). We show that the order within the supracrystals is temperature-dependent when they are made of hexadecanethiol-coated gold nanocrystals, regardless of the size of the nanocrystals. The interparticle distances within the various supracrystals that were produced were determined by small-angle X-ray diffraction (SAXRD). We demonstrate that the interparticle distance is controlled not only by the presence of physisorbed thiol residues, as previously reported, but also, at higher temperatures, by the dynamics of the organic chains and the van der Waals forces involved between the metallic cores of the nanocrystals forming the structure.

Effect of metal complexation on the conductance of single-molecular wires measured at room temperature.

The present work aims to give insight into the effect that metal coordination has on the room-temperature conductance of molecular wires. For that purpose, we have designed a family of rigid, highly conductive ligands functionalized with different terminations (acetylthiols, pyridines, and ethynyl groups), in which the conformational changes induced by metal coordination are negligible. The single-molecule conductance features of this series of molecular wires and their corresponding Cu(I) complexes have been measured in break-junction setups at room temperature. Experimental and theoretical data show that no matter the anchoring group, in all cases metal coordination leads to a shift toward lower energies of the ligand energy levels and a reduction of the HOMO-LUMO gap. However, electron-transport measurements carried out at room temperature revealed a variable metal coordination effect depending on the anchoring group: upon metal coordination, the molecular conductance of thiol and ethynyl derivatives decreased, whereas that of pyridine derivatives increased. These differences reside on the molecular levels implied in the conduction. According to quantum-mechanical calculations based on density functional theory methods, the ligand frontier orbital lying closer to the Fermi energy of the leads differs depending on the anchoring group. Thereby, the effect of metal coordination on molecular conductance observed for each anchoring could be explained in terms of the different energy alignments of the molecular orbitals within the gold Fermi level.

Profiling thiol metabolites and quantification of cellular glutathione using FT-ICR-MS spectrometry.

We describe preparation and use of the quaternary ammonium-based α-iodoacetamide QDE and its isotopologue *QDE as reagents for chemoselective derivatization of cellular thiols. Direct addition of the reagents to live cells followed by adduct extraction into n-butanol and analysis by FT-ICR-MS provided a registry of matched isotope peaks from which molecular formulae of thiol metabolites were derived. Acidification to pH 4 during cell lysis and adduct formation further improves the chemoselectivity for thiol derivatization. Examination of A549 human lung adenocarcinoma cells using this approach revealed cysteine, cysteinylglycine, glutathione, and homocysteine as principal thiol metabolites as well as the sulfinic acid hypotaurine. The method is also readily applied to quantify the thiol metabolites, as demonstrated here by the quantification of both glutathione and glutathione disulfide in A549 cells at concentrations of 34.4 ± 11.5 and 10.1 ± 4.0 nmol/mg protein, respectively.

Nitrilotriacetic Acid–Copper(II) Monolayer Deposited on a Gold Electrode for the Immobilization of Histidine Tagged V Domain of Receptor for Advanced Glycation End Products–The Basis of Amyloid–Beta Peptide Sensing

The preparation and application of biosensors for the determination of amyloid-beta16–23′ peptide are described. The redox active nitrilotriacetic acidsingle-copper(II)-histidine6-receptor for advanced glycation end products V domain and redox active nitrilotriacetic aciddouble-Cu(II)-histidine6-receptor for advanced glycation end products V domain complexes were employed as an analytically active layer of biosensors. The preparation procedure consists of three steps: creation of a mixed layer composed of N-acetylocysteamine and thiol derivatives of nitrilotriacetic acid, complexation of Cu(II) on the N-acetylocysteamine-nitrilotriacetic acid layer, and immobilization of histidine-tagged V domains, natural or mutant on the surface of a gold electrode modified with a N-acetylocysteamine-nitrilotriacetic acid layer. The biosensors were used for the study of the interactions between the histidine-tagged V domains of receptor for advanced glycation end products and amyloid-beta16–23′ peptide. Each step was controlled by cyclic voltammetry, Osteryoung square-wave voltammetry, and atomic force microscopy. Comparisons of the electrochemical parameters of biosensors, incorporating single as well as double nitrilotriacetic acid molecules, were investigated. Both types of biosensors were used for determination of amyloid-beta16–23′ peptide, and the mechanism of electroanalytical signals generation is reported.

Ruthenium Nanoparticles Stabilized by the Self-Assembly of Acetylene, Carboxylate, and Thiol Derivatives

Ruthenium Nanoparticles Stabilized by the Self-Assembly of Acetylene, Carboxylate, and Thiol Derivatives

P74: The reaction between H2S and 8-nitro-cGMP: Substitution or reduction?

Amongst the molecular reactions of H2S accounting for its role as gaseous transmitter is the reaction between hydrogen sulfide and electrophiles. The reaction between H2S and 8-NO2-guanosine 3 ′ , 5 ′ -cyclic monophosphate (8-NO2-cGMP) leading to the thiol derivative 8-SH-cGMP by “sulfhydration” was proposed to take place in cells, but the chemical reaction is in fact sluggish and requires the catalysts cysteine and transition metals or metalloproteins (Nishida et al., Nat. Chem. Biol. 8 (2012) 714–724). In this work, we show that the direct reaction between H2S and 8-NO2-guanosine (8-NO2-Gua, used as a model of 8-NO2-cGMP) or 8-NO2-cGMP does not lead to the substitution of the nitro group by HS−, but to a redox reaction yielding the radical [8-NO2-Gua]·-. Because of futile redox cycling with dioxygen, the reaction does not proceed further. However, under hypoxic conditions the reaction between H2S and 8-NO2-cGMP goes to completion and yields the amino derivative 8-NH2-cGMP, a reaction which may be relevant to the first step in the cellular recycling of 8-NO2-cGMP into cGMP.

Gold(I) complexes with alkylated PTA (1,3,5-triaza-7-phosphaadamantane) phosphanes as anticancer metallodrugs

New stable thiolate gold(I) derivatives containing the alkylated phosphanes [PTA–CH2Ph]Br and [PTA–CH2COOMe]Br derived from 1,3,5-triaza-7-phosphaadamantane (PTA) have been prepared by different routes of synthesis. By the use of basic media to deprotonate the corresponding thiol in the former and by transmetallation reactions from tin (IV) complexes, in the later, thus avoiding side reactions on the phosphane. Strong antiproliferative effects are observed for most of the compounds, including the chloro- and bromo precursors with the series of phosphanes derived from PTA, in human colon cancer cell lines (Caco-2, PD7 and TC7 clones). Apoptosis-induced cell death is found for all compounds, being the thiolate derivatives with [PTA–CH2Ph]Br the most effective, as shown by an annexin-V/propidium iodide double-staining assay.

Therapy modifies cystine kidney stones at the macroscopic scale. Do such alterations exist at the mesoscopic and nanometre scale?

With an incidence of 1:7000 births, cystinuria, the most frequent cause of stone formation among genetic diseases, represents a major medical problem. Twenty-five cystine stones randomly selected from cystinuric patients were investigated. From a crystallographic point of view, cystine stones are composed of micrometre size crystallites, which are made up of an aggregation of nanocrystals. Through scanning electron microscopy, the morphology and size of the crystallites have been described, while the size of the nanocrystals was investigated by means of powder neutron diffraction. Powder neutron diffraction analysis and/or scanning electron microscopy examination of cystine stones provide evidence that usual alkalinization by sodium bicarbonate associated with high diuresis significantly reduces the size of both nanocrystals and crystallites, while for other treatments, including alkalinizing drugs and thiol derivatives, the data suggest mainly changes in the topology of crystallites. Alkalinization with sodium bicarbonate affects cystine kidney stones at the mesoscopic and nanoscopic scales, while other medical treatments only alter their surface. Such an approach may help to assess the interaction between drugs and cystine stones in cystinuric patients.

Molecular Basis for the Antiparasitic Activity of a Mercaptoacetamide Derivative That Inhibits Histone Deacetylase 8 (HDAC8) from the Human Pathogen Schistosoma mansoni

Schistosomiasis, caused by the parasitic flatworm Schistosoma mansoni and related species, is a tropical disease that affects over 200 million people worldwide. A new approach for targeting eukaryotic parasites is to tackle their dynamic epigenetic machinery that is necessary for the extensive phenotypic changes during the life cycle of the parasite. Recently, we identified S. mansoni histone deacetylase 8 (smHDAC8) as a potential target for antiparasitic therapy. Here, we present results on the investigations of a focused set of HDAC (histone deacetylase) inhibitors on smHDAC8. Besides several active hydroxamates, we identified a thiol-based inhibitor that inhibited smHDAC8 activity in the micromolar range with unexpected selectivity over the human isotype, which has not been observed so far. The crystal structure of smHDAC8 complexed with the thiol derivative revealed that the inhibitor is accommodated in the catalytic pocket, where it interacts with both the catalytic zinc ion and the essential catalytic tyrosine (Y341) residue via its mercaptoacetamide warhead. To our knowledge, this is the first complex crystal structure of any HDAC inhibited by a mercaptoacetamide inhibitor, and therefore, this finding offers a rationale for further improvement. Finally, an ester prodrug of the thiol HDAC inhibitor exhibited antiparasitic activity on cultured schistosomes in a dose-dependent manner.

Surface properties of new catanionic semi-fluorinated hybrid surfactants

In order to study their aggregation behaviour, a rapid synthetic procedure from perfluoroalkylethyl thiol derivatives led to twenty four original catanionic hybrid surfactants of general formula: [RF(CH2)2S(CHQ)2CO2−; HN+(CH3)2RH (Q=H or Cl; RF=C4F9, C6F13, C8F17; RH=C6H13, C8H17, C10H21, C12H25)]. Critical aggregation concentration (CAC), surface tension at the CAC (γS) and free energy of aggregation (ΔGA°) of the title surfactants, in aqueous solution, have been investigated as a function of the number of carbon atoms in both the fluorinated and the hydrocarbon tails. TEM studies were used to estimate the shape and size of the aggregates and confirmed the general tendency of fluorinated surfactants to form aggregates with lesser curvature. These catanionic surfactants exhibited very low surface tension at critical aggregation concentration (CAC) of 15.3–17.4mNm−1 as well as low CAC of 3×10−5–11×10−3 and the substitution of one hydrogen atom by one chlorine atom didn’t affect significantly the aggregation phenomenon.

ChemInform Abstract: Simple Synthesis of Sulfonyl Chlorides from Thiol Precursors and Derivatives by NaClO2‐Mediated Oxidative Chlorosulfonation.

ChemInformVolume 45, Issue 9 Preparative Organic Chemistry ChemInform Abstract: Simple Synthesis of Sulfonyl Chlorides from Thiol Precursors and Derivatives by NaClO2-Mediated Oxidative Chlorosulfonation. Zhanhui Yang, Zhanhui Yang Dep. Org. Chem., Fac. Sci., Beijing Univ. Chem. Technol., Beijing 100029, Peop. Rep. ChinaSearch for more papers by this authorYongpeng Zheng, Yongpeng Zheng Dep. Org. Chem., Fac. Sci., Beijing Univ. Chem. Technol., Beijing 100029, Peop. Rep. ChinaSearch for more papers by this authorJiaxi Xu, Jiaxi Xu Dep. Org. Chem., Fac. Sci., Beijing Univ. Chem. Technol., Beijing 100029, Peop. Rep. ChinaSearch for more papers by this author Zhanhui Yang, Zhanhui Yang Dep. Org. Chem., Fac. Sci., Beijing Univ. Chem. Technol., Beijing 100029, Peop. Rep. ChinaSearch for more papers by this authorYongpeng Zheng, Yongpeng Zheng Dep. Org. Chem., Fac. Sci., Beijing Univ. Chem. Technol., Beijing 100029, Peop. Rep. ChinaSearch for more papers by this authorJiaxi Xu, Jiaxi Xu Dep. Org. Chem., Fac. Sci., Beijing Univ. Chem. Technol., Beijing 100029, Peop. Rep. ChinaSearch for more papers by this author First published: 14 February 2014 https://doi.org/10.1002/chin.201409053Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume45, Issue9March 4, 2014 RelatedInformation

Use of graphene as protection film in biological environments

Corrosion of metal in biomedical devices could cause serious health problems to patients. Currently ceramics coating materials used in metal implants can reduce corrosion to some extent with limitations. Here we proposed graphene as a biocompatible protective film for metal potentially for biomedical application. We confirmed graphene effectively inhibits Cu surface from corrosion in different biological aqueous environments. Results from cell viability tests suggested that graphene greatly eliminates the toxicity of Cu by inhibiting corrosion and reducing the concentration of Cu2+ ions produced. We demonstrated that additional thiol derivatives assembled on graphene coated Cu surface can prominently enhance durability of sole graphene protection limited by the defects in graphene film. We also demonstrated that graphene coating reduced the immune response to metal in a clinical setting for the first time through the lymphocyte transformation test. Finally, an animal experiment showed the effective protection of graphene to Cu under in vivo condition. Our results open up the potential for using graphene coating to protect metal surface in biomedical application.

Preparation of monodispersed carboxylate-functionalized gold nanoparticles using pamoic acid as a reducing and capping reagent

A simple preparation method of gold nanoparticles (AuNPs) using pamoic acid (PA; 4,4′-methylene-bis(3-hydroxy-2-naphthalene carboxylic acid)) with NaOH is described. Although PA is insoluble in water, it can be dissolved in the presence of NaOH and function as a capping and reducing reagent to form the AuNPs. The thus-formed AuNPs have a good monodispersity with diameters of 10.8 ± 1.2 nm and carboxylate functions that come from the PA. Because PA is a methylene-bridged dimer of 3-hydroxy-2-naphthalene carboxylic acid, the formation of the AuNPs was examined also using the analogous monomer molecules, i.e., 3-hydroxy-2-naphthalene carboxylic acid, 2-hydroxy-1-naphtalene carboxylic acid, or 2-naphthol. Consequently, it was found that the case of PA was specific to forming the spherical monodispersed AuNPs while that differently shaped Au nanostructures were formed in the other cases. The present preparation using PA would be an interesting example that stable, monodispersed, carboxylate-functionalized AuNPs could be prepared without using thiols. Also, the present results may provide some insight into molecular designs of capping reagents for preparing functionalized AuNPs without using thiol derivatives.

“One‐pot” synthesis of well‐defined functional copolymer and its application as tumor‐targeting nanocarrier in drug delivery

ABSTRACTA one‐pot synthesis is developed for PEG600‐b‐poly(glycerol monoacrylate) (PEG600‐b‐PGA), by which folate and superparamagnetic iron oxide nanoparticles (SPIONs) are assembled to form folic acid‐conjugated magnetic nanoparticles (FA‐MNPs) as a tumor targeting system. The synthesis consists of a “click” reaction and atom transfer radical polymerization (ATRP) to obtain the well‐defined furan‐protected maleimido‐terminated PEG600‐b‐poly(solketal acrylate) (PEG600‐b‐PSA) copolymer. After deprotection, the key copolymer N‐maleimido‐terminated PEG600‐b‐PGA is successfully conjugated with thiol derivatives of folate and FITC, respectively. FA‐MNPs are developed by assembling of the resulting polymer FA‐PEG600‐b‐PGA with SPIONs, and characterized for their size, surface charge, and superparamagnetic properties. To investigate the cellular uptake of the nanoparticles by Hela cells and φ2 cells using fluoresce technique, FA‐FITC‐MNPs are also obtained by assembling of FA‐PEG600‐b‐PGA, FITC‐PEG600‐b‐PGA with SPIONs. Qualitative and quantitative determinations of FA‐FITC‐MNPs show that the particles specifically internalized to Hela cells. No significant cytotoxicity is observed for these two kinds of cell lines. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40405.

Synthesis of new amphiphilic water‐stable hyperbranched polycarbosilane polymers

AbstractNew amphiphilic hyperbranched polymers possessing hydrophobic skeletons and hydrophilic terminal groups have been prepared and characterized. The synthetic strategy involved the formation of a new stable matrix with aromatic units within a carbosilane backbone, as well as the use of a classical polycarbosilane matrix. Both of them with allyl groups on the surface have narrow polydispersity values. Molecular weight and polydispersity of the hyperbranched polymers were obtained using gel permeation chromatography with multi‐angle light scattering, and determination of the average number of functional groups present on the surface was achieved using 1H NMR spectroscopy. The introduction of ionic groups was carried out via thiol–ene reactions with various thiol derivatives. The thermal properties of the polymers were also analysed using differential scanning calorimetry and zeta potential measurements. © 2013 Society of Chemical Industry

Nucleophilic addition of carborane anion to Ir, Rh-coordinated Cp* ring: C–C bond formation accompanied by reduction of metal center

Reaction of carboranyl anion or its thiolate derivative with a fully-substituted Cp*-based group 9 (Ir, Rh) metal complex affords respectively a C-C bond formation complex and a salt metathesis product. This example represents the first nucleophilic addition attempt in the area of M-Cp* chemistry.

Potential usage for in vivo lectin screening in live animals utilizing cell surface mimetic glyco-nanoparticles, phosphorylcholine-coated quantum dots (PC-QDs).

Utilizing glycosylated derivatives as a tag, we are able to explore novel counter-receptor of endogenous lectins or lectin-like molecules in vivo. We have established the standardized methodology including preparation of glycosylated derivatives and construction of a platform for tracing the molecules in vivo at first. Combined use of an aminooxy-terminated thiol derivative and a phosphorylcholine (PC) derivative provides quantum dots (QDs) with novel functions for the chemical ligation of ketone-functionalized compounds and the prevention of nonspecific protein adsorption concurrently. In order to track the derivatives in vivo, near-infrared (NIR) fluorescence imaging of QDs displaying various simple sugars (glyco-PC-QDs) after administration into the tail vein of the mouse can be performed. It has revealed that distinct long-term delocalization over 2 h can be observed depending on the species of glycans ligated to PC-QDs at least in the liver. Until today we have performed live animal imaging utilizing various kinds of sialyl glyco-PC-QDs. They are still retained stably in whole body after 2 h while they showed significantly different in vivo dynamics in the tissue distribution, suggesting that structure/sequence of the neighboring sugar residues in the individual sialyl oligosaccharides might influence the final organ-specific distribution, which should be equivalent to the distribution of sialic acid-recognizing lectins. Here we describe a standardized protocol using ligand-displayed PC-QDs for live cell/animal imaging by versatile NIR fluorescence photometry without influence of size-dependent accumulation/excretion pathway for nanoparticles (e.g., viruses)>10 nm in hydrodynamic diameter by the liver.

Zone Fluidics Derivatization of Thiols Under Flow Conditions by 2-Chloro-1-methylquinolinium Tetrafluoroborate

The present investigation reports—for the first time—data on the reaction of the derivatization reagent 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT) with thiols under flow conditions. By adopting the concept of zone-fluidics, we examined various chemical parameters of the reaction and applied the stopped-flow technique for kinetic studies. CMQT proved to react rapidly with model thiol compounds under flow conditions and alkaline media, offering promising data for future applications such as liquid chromatography coupled to on-line post-column derivatization. Furthermore, the potential of the reagent was demonstrated by developing an automated flow method for the quality control of methimazole-containing formulations. Following validation experiments, the latter were determined in assay and dosage uniformity quality control tests of commercially available formulations with a limit of detection of 0.24 mg L−1, precision better than 1.5%, and a sampling rate of 30 h−1. [Supplementary materials are available for this article. Go to the publisher's online edition of Analytical Letters for the following free supplemental resource(s): Additional figures.]

Formation of host–guest complexes on gold surface investigated by surface-enhanced IR absorption spectroscopy

We apply surface-enhanced infrared absorption (SEIRA) spectroscopy to host–guest complexes in liquid phase to examine the structural change in the complex formation. Two thiol derivatives of 18-crown-6 (18C6) are chemisorbed on a gold surface, and aqueous solutions of MCl salts (M=Li, Na, K, Rb, and Cs) are put to form M+·18C6 complexes. Infrared spectra of these complexes in the 900–2000cm−1 region are obtained by SEIRA spectroscopy. The observed IR spectra show noticeable peaks due to the complex formation, demonstrating that SEIRA spectroscopy will be a powerful method to investigate the structure of host–guest complexes in supramolecular chemistry.

Hierarchy in Au Nanocrystal Ordering in a Supracrystal: II. Control of Interparticle Distances

Au nanocrystals coated with thiol derivatives differing by the length of their alkyl chains are used to build 3D superlattices called supracrystals. In this study, we used two sets of Au nanocrystals differing by their sizes and size distributions. The average sizes are 5 nm (Au5) and 7 nm (Au7). From one experiment to the other, the size distribution slightly changes. For Au5 nanocrystals, it evolves from 6 to 8%, and for Au7 nanocrystals, it varies from 5 to 6%. The Au nanocrystals (Au5 and Au7) are first dispersed in toluene and produce fcc supracrystals by solvent evaporation. Here, by small-angle grazing X-ray diffraction, we observe a control in the average interparticle distance within the supracrystals. When the supracrystals are grown at zero toluene vapor pressure, the interparticle distances increase linearly with the alkyl chain length of the nanocrystals' coating agent regardless of their diameters. Furthermore, the dry supracrystals can swell and the interparticle distance within the superstructure be increased by subjecting the material to toluene vapor pressure after initial growth. This swelling process is reversible, and retraction occurs when the toluene vapor pressure drops. This indicates a strong ability of the dried supracrystals to trap toluene molecules. On increasing the toluene vapor pressure during the solvent evaporation process, the slope of the linear dependency of the interparticle distances to the alkyl chain length is markedly decreased and the interparticle distance reaches a quasi-plateau. This is explained by the influence of depletion forces created by the presence of thiol-containing molecules physisorbed on the coating molecules on the internal structure of these supracrystals. Recently, we demonstrated that, by using the same nanocrystals (Au5 and Au7), a hierarchy in the supracrystal growth process takes place from heterogeneous nucleation with the formation of a layer-by-layer film to homogeneous nucleation in solution with the formation of shaped supracrystals. Here it is shown that the interparticle distance is independent of the supracrystal growth mechanisms.