Detection of bacterial quorum sensing <Emphasis Type="Italic">N</Emphasis>-acyl homoserine lactones in clinical samples

Bacteria communicate among themselves using certain chemical signaling molecules. These signaling molecules generally are N-acyl homoserine lactones (AHLs) in Gram-negative bacteria and oligopeptides in Gram-positive bacteria. In addition, both Gram-positive and Gram-negative bacteria produce a family of signaling molecules known as autoinducer-2 that they employ for their communications. Bacteria coordinate their behavior by releasing and responding to the chemical signaling molecules present in proportion to their population density. This phenomenon is known as quorum sensing. The role of bacteria in the pathogenesis of several diseases, including gastrointestinal (GI) disorders, is well established. Moreover, rather recently bacterial quorum sensing has been implicated in the onset of bacterial pathogenicity. Thus, we hypothesized that the signaling molecules involved in bacterial communication may serve as potential biomarkers for the diagnosis and management of several bacteria-related diseases. For that, we previously developed a method based on genetically engineered whole-cell sensing systems for the rapid, sensitive, cost-effective and quantitative detection of AHLs in biological samples, such as saliva and stool, from both healthy and diseased individuals with GI disorders. Although various analytical methods, based on physical-chemical techniques and bacterial whole-cell biosensors, have been developed for the detection of AHLs in the supernatants of bacterial cultures, only a few of them have been applied to AHL monitoring in real samples. In this paper, we report work performed in our laboratory and review that from others that describes the detection of AHLs in biological, clinical samples, and report some of our recent experimental results.     

Nanocatalosomes as Plasmonic Bilayer Shells with Interlayer Catalytic Nanospaces for Solar‐Light‐Induced Reactions

Interest and challenges remain in designing and synthesizing catalysts with nature‐like complexity at few‐nm scale to harness unprecedented functionalities by using sustainable solar light. We introduce “nanocatalosomes”—a bio‐inspired bilayer‐vesicular design of nanoreactor with metallic bilayer shell‐in‐shell structure, having numerous controllable confined cavities within few‐nm interlayer space, customizable with different noble metals. The intershell‐confined plasmonically coupled hot‐nanospaces within the few‐nm cavities play a pivotal role in harnessing catalytic effects for various organic transformations, as demonstrated by “acceptorless dehydrogenation”, “Suzuki–Miyaura cross‐coupling” and “alkynyl annulation” affording clean conversions and turnover frequencies (TOFs) at least one order of magnitude higher than state‐of‐the‐art Au‐nanorod‐based plasmonic catalysts. This work paves the way towards next‐generation nanoreactors for chemical transformations with solar energy.     

Photochemical C–N bond forming reactions for the synthesis of five-membered fused N-heterocycles

Abstract

Few conversions cannot take place with ground-state reactions even with the help of a catalyst, therefore they are made to occur under photochemical conditions. The transfer of electrons took place even with the photochemical excitement of one molecule where redox reaction cannot occur at the ground state. The ground-state reactions resulted in the formation of side products. The substrates did not require any sort of chemical activation for C–N bond construction in the course of photochemical reactions. The source of energy; light has always been the interest of researchers in order to induce chemical reactions ever since the starting of scientific chemistry. The present review encloses the chemistry of photochemical transformations with a focus on their synthetic uses. The organic photochemical reactions prevent the polluting or harmful reagents thus, provides a possibility for sustainable procedures as well as green chemistry. This review article displays the formation of numerous of five-membered fused nitrogen-heterocyclic compounds.     

Recent Advances in the Applications of Ionic Liquids in Protein Stability and Activity: A Review

Room temperatures ionic liquids are considered as miraculous solvents for biological system. Due to their inimitable properties and large variety of applications, they have been widely used in enzyme catalysis and protein stability and separation. The related information present in the current review is helpful to the researchers working in the field of biotechnology and biochemistry to design or choose an ionic liquid that can serve as a noble and selective solvent for any particular enzymatic reaction, protein preservation and other protein based applications. We have extensively analyzed the methods used for studying the protein–IL interaction which is useful in providing information about structural and conformational dynamics of protein. This can be helpful to develop and understanding about the effect of ionic liquids on stability and activity of proteins. In addition, the affect of physico-chemical properties of ionic liquids, viz. hydrogen bond capacity and hydrophobicity on protein stability are discussed.     

Bismuthiol II as an analytical reagent

Summary Silver can be separated as its Bismuthiol II complex from OsO_{4 4} ^2– , Os⁴⁺, Ir⁴⁺, Ru³⁺, Rh³⁺ with thiosulphate or complexone III as the masking agent at a p_H between 5 and 9. Au³⁺ can be kept in solution only by thiosulphate at a p_H 8–9 and cyanide complexes palladium at a P_H of about 6. Separation from platinum in presence of a mixture of tartaric acid and complexone III is possible only to a limited extent.Part VI see Z. analyt. Chem. 155, 86 (1957)     

Bis-salicylaldehyde-ethylenediamine as an analytical reagent

Summary Copper has been determined gravimetrically as its bis-salicylaldehyde-ethylenediamine complex of the composition C₁₆H₁₄O₂N₂ · Cu, dried at 100–120° C. The complex is completely precipitated in theph range of 10.5–13.5, adjusted with ammonia or caustic alkali. It is stable in presence of excess ammonia, 0.1 N alkali, ammonium salts and complexing agents as tartrate, citrate, sodium-thiosulphate, fluoride, thiourea, triethanolamine and EDTA. In presence of tartrate and ammonia the ions of alkali metals, alkaline earths, Ag⁺, Tl⁺, Tl³⁺, Pb²⁺, Cd²⁺, Co²⁺, Mn²⁺, Pd²⁺, Al³⁺, Cr³⁺, La³⁺, Ce³⁺, Au³⁺, Pt⁴⁺, Ti⁴⁺, Zr⁴⁺, Th⁴⁺, UO₂ ²⁺ and anions as VO₃ ^–, MoO₄ ^2–, WO₄ ^2–, CrO₄ ^2–, PO₄ ^3–, AsO₄ ^3– do not interfere. Ni²⁺ and Hg²⁺ are masked by tartrate, EDTA and ammonia; As³⁺, Sb³⁺ and Sn²⁺ are separated using fluoride as the complexing agent; at an alkalinity of 0.1 N caustic alkali in presence of tartrate As³⁺, Sb³⁺, Sn²⁺, Bi³⁺, Zn²⁺ and Fe³⁺ are separated. Fe³⁺ can also be separated using triethanolamine as the masking agent at aph of about 13.0. Copper can be separated from almost all the ions, thus affording a highly selective method for the determination of copper.

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Zusammenfassung Es wird eine gravimetrische Methode zur Bestimmung von Kupfer beschrieben, die auf der Bildung des Bis-salicylaldehyd-äthylendiaminkomplexes beruht. Dieser hat die Zusammensetzung C₁₆H₁₄O₂N₂ · Cu. Die Fällung wird imph-Bereich 10,5–13,5 (mit Ammoniak oder Alkalilauge eingestellt) vorgenommen und der Niederschlag bei 100°–120° C getrocknet. Der Komplex ist beständig in Gegenwart von überschüssigem Ammoniak, 0,1 n Alkali, Ammoniumsalzen sowie Tartrat, Citrat, Natriumthiosulfat, Fluorid, Thioharnstoff, Triäthanolamin und ÄDTA. In Gegenwart von Tartrat und Ammoniak stören nicht: Alkalien, Erdalkalien, Ag⁺, Tl⁺, Tl³⁺, Pb²⁺, Cd²⁺, Co²⁺, Mn²⁺, Pd²⁺, Al³⁺, Cr³⁺, La³⁺, Ce³⁺, Au³⁺, Pt⁴⁺, Ti⁴⁺, Zr⁴⁺, Th⁴⁺, UO₂ ²⁺ sowie VO₃ ^–, MoO₄ ^2–, WO₄ ^2–, CrO₄ ^2–, PO₄ ^3– und AsO₄ ³⁺. Ni²⁺ und Hg²⁺ können mit Tartrat, ÄDTA und Ammoniak maskiert werden, As³⁺, Sb³⁺ und Sn²⁺ mit Fluorid. In 0,1 n ätzalkalischer Lösung in Gegenwart von Tartrat können As³⁺, Sb³⁺, Sn²⁺, Bi³⁺, Zn²⁺ und Fe³⁺ abgetrennt werden. Fe³⁺ kann ebenfalls mit Triäthanolamin beiph 13,0 maskiert werden. Das beschriebene Verfahren erlaubt somit eine Abtrennung des Kupfers von fast allen anderen Ionen.

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Part I: Singh, B. R., and S. Kumar: Z. analyt. Chem. 185, 211 (1962).     

Solid-state synthesis, structural variants and transformation of three-dimensional sulfides, AGaSnS4 (A=Na, K, Rb, Cs, Tl) and Na1.263Ga1.263Sn0.737S4

New cubic-AGaSnS₄ (A=Na, K, Rb, Cs, Tl) and orthorhombic-NaGaSnS₄ compounds were synthesized by solid-state reactions and characterized by X-ray diffraction and diffuse reflectance spectroscopy. Single crystals of orthorhombic-Na_1.263Ga_1.263Sn_0.737S₄ were obtained in the crystal growth attempts of sodium compound. All six new compounds have orthorhombic AgGaGeS₄ and cubic BaGa₂S₄ structures, as determined from single crystal X-ray structures of Na_1.263Ga_1.263Sn_0.737S₄ and cubic-AGaSnS₄ (A=Na, K, Rb). Orthorhombic-NaGaSnS₄ and known layered-KGaSnS₄ undergo structural transformation to thermodynamically stable cubic form.     

Redox Behavior of Neptunium(V) in Tributyl Phosphate and <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dihexyl Octanamide Extractants Dissolved in <Emphasis Type="Italic">n</Emphasis>-Dodecane

Spectrophotometric investigations have been carried out on the disproportionation of Np(V) to form Np(IV) and Np(VI) in 1.1 mol⋅L⁻¹ solutions of tributyl phosphate (TBP) and in N,N-dihexyl octanamide (DHOA) in n-dodecane medium. The Np(V) was found to coordinate with Np(IV) in 1.1 mol⋅L⁻¹ TBP solution in n-dodecane to form a mixed valence “cation–cation” complex by bonding through an axial oxo group on Np(V). By contrast, this interaction was less prominent in the case of 1.1 mol⋅L⁻¹ DHOA solutions. The effect of 1-octanol, added as phase modifier, on the disproportionation behavior of Np(V) was also investigated. An attempt was made to calculate the disproportionation/reduction rate constants for Np(V) under the conditions of these studies. Absorbance measurements on the Np stripped from organic phases revealed the occurrence of Np(V) in the aqueous phase.     

A Chemodosimetric Probe Based on a Conjugated Oxidized Bis‐Indolyl System for Selective Naked‐Eye Sensing of Cyanide Ions in Water

A new bis‐indolyl‐based colorimetric probe has been synthesized. This allows a Michael‐type adduct formation for the detection of cyanide ions. The probe shows a remarkable color change from red to colorless upon addition of the cyanide ions in pure water. The cyanide ion reacts with the probe and removes the conjugation of the bis‐indolyl moiety of the probe with that of the 4‐substituted aromatic ring. This renders the probe colorless. The mechanism of the reaction of the probe with the cyanide ion was established by using ¹H and ¹³C NMR spectroscopy, mass spectrometry, and kinetic studies.     

Palladium-catalyzed regioselective synthesis of benzosultams from functionalized ynamides and benzotriazoles/tetrazoles

Palladium-catalyzed highly regioselective synthesis of benzotriazole appended benzosultams by the tandem-cyclization of functionalized ynamides with benzotriazoles has been accomplished. This transformation involves the formation of both CN and CC bonds in a single step. Donor solvents appear to enhance the yields of the products. The methodology is also applicable for the generation of triazole/tetrazole appended benzosultams.