A novel antibody–antigen based impedimetric immunosensor for low level detection of HER2 in serum samples of breast cancer patients via modification of a gold nanoparticles decorated multiwall carbon nanotube-ionic liquid electrode

A highly sensitive impedimetric immunosensor based on a gold nanoparticles/multiwall carbon nanotube-ionic liquid electrode (AuNPs/MW-CILE) was developed for the determination of human epidermal growth factor receptor 2 (HER2). Gold nanoparticles were used to enhance the extent of immobilization and to retain the immunoactivity of the antibody Herceptin on the electrode. Cyclic voltammetry and electrochemical impedance spectroscopy were employed for characterization of various layers coated onto the AuNPs/MW-CILE. The impedance measurements at different steps were based on the charge transfer kinetics of the [Fe(CN)₆]^3−/4− redox pair. The immobilization of antibody and the corresponding antigen–antibody interaction at the electrode surface altered the interfacial electron transfer. The interactions of antibody with various concentrations of antigen were also monitored via the change of impedance response. The results showed that the charge transfer resistance increases linearly with increasing concentrations of HER2 antigen. The linear range and limit of detection were found as 10–110 ng mL⁻¹ and 7.4 ng mL⁻¹, respectively. The sensitivity and specificity of the immunosensor were validated. The results showed that the prepared immunosensor is a useful tool for screening of trace amounts of HER2 in serum samples of breast cancer patients.     

Sulfonated magnetic sugarcane bagasse as an efficient natural polymer-based catalyst for the synthesis of nitrogen-containing heterocyclic rings in water

Molecular Diversity - A new species of catalysts that are prepared from biocompatible materials is demonstrated. Sulfonated magnetic sugarcane bagasse has been synthesized as a novel biodegradable...     

Synthesis of 1,2,4,5‐Tetrasubstituted Imidazoles Using Sulfuric Acid ([3‐(3‐Silicapropyl)sulfanyl]propyl]ester as a Recyclable Solid Acid

Sulfuric acid ([3‐(3‐silicapropyl)sulfanyl]propyl]ester (SASPSPE) is used as a recyclable catalyst for the synthesis of 1,2,4,5‐tetrasubstituted imidazoles. A range of various polysubstituted imidazoles was synthesized via four‐component condensation of benzil, aldehydes, amines, and ammonium acetate in the presence of SASPSPE under solvent‐free conditions at 140°C. The heterogeneous catalyst was recycled for five runs on the reaction of benzil, 4‐methylbenzaldehyde, benzyl amine, and ammonium acetate without losing its catalytic activity.     

Synthesis of novel 5-substituted isophthalates from vinamidinium salts

Novel 5-substituted isophthalates were synthesized from the reaction of 2-substituted 1,3-bis(dimethylamino)-trimethinium salts with 1,3-bis(alkoxycarbonyl)acetone derivatives in the presence of sodium methoxide in ethanol at reflux.     

Nuclear Quadrupole Resonance and Stereochemistry I. α – Chloro ethers

³⁵Cl nuclear quadrupole resonance spectra of cyclic α-chloro ethers of known configuration are presented. The resonance frequencies of chlorine atoms in equatorial positions are in every case some 2.5 MHz higher than those of corresponding chlorine atoms in axial positions. Similar results are obtained for open-chain trichloromethyl ethers and the effect is sufficiently well-defined to distinguish between configurational isomers and establish their conformation. These results may be rationalised in terms of a model in which the lone-pair electrons on the oxygen atom hyperconjugate with the electrons of the C? Cl bond.     

2-(Sulfooxy)propane-1,2,3-tricarboxylic acid as novel and versatile catalyst for the formylation of alcohols and amines using ethyl formate under neat conditions

2-(Sulfooxy)propane-1,2,3-tricarboxylic acid(supported on silica gel) has been introduced as novel and green catalyst for the formylation of alcohols and amines with ethyl formate,as mild formylation agent,under neat conditions at room temperature.     

Electrocatalytic Determination of Traces of Hydrazine by a Glassy Carbon Electrode Modified with Palladium‐Gold Nanoparticles

A glassy carbon electrode modified with palladium/gold nanoparticles was successfully prepared by an electrodeposition process. It efficiently oxidizes hydrazine at a low overpotential of ?0.26 V versus SCE. The Pd‐AuNPs with an average size of 50–80 nm are uniformly dispersed at the GCE. The Pd‐AuNPs/GCE was used for determination of hydrazine in phosphate buffer solution of pH 7.0. The amperometric current response of the electrode was increased linearly over a hydrazine concentration of 0.1–500 µM with a limit of detection of 0.07 µM .The prepared hydrazine sensor exhibited high sensitivity, good selectivity reproducibility and long term stability.     

Synthesis and Characterization of a Novel Phosph(V)azane-Tin(IV) Complex

Abstract

The reaction of bis(anilino)phosphine oxide (C₆H₅NH)₂P(O)H, 1 with Bu₂ ⁿSnCl₂ in the presence of an excess of triethylamine (TEA) in dry tetrahydrofurane (THF) yields the novel N,O-bonded tin complex Bu₂ ⁿSn[NPh(O)P(H)NPh(HNEt₃)]₂, 2. TEA is used as a base to deprotonate the phosphazane ligand and is separated as Et₃NH⁺Cl^?, whereas HTEA⁺ exists in the final product 2 and act as a charge balancing and H-bond structure–directing agent. This new compound has been fully characterized by means of IR, MS, and multinuclear (¹H, ³¹P, and ¹¹⁹Sn NMR) spectroscopy.