Exploring the structural,electronic and optical properties of furan-2-carboxaldehyde and 2-acetylthiophene nicotinoylhydrazone

The crystal and molecular structures of nicotinohydrazide-derived hydrazones, N′-(2-furfurylidene)pyridine-3-carbohydrazide and N′-(1-(2-thienyl)ethylidene)pyridine-3-carbohydrazide, have been determined. The compounds have been also characterized by the solid state IR and UV–Vis spectroscopy. The hydrazones exist in the keto-amine form. According to the results of molecules quantum–mechanical calculations, performed for isolated molecules, this tautomeric form is energetically unfavorable but in the solid and solution states the observed intermolecular interactions support the presence of this form. The furan derivative crystallizes in two polymorphic forms with two molecules in an asymmetric unit regardless of the crystallization method.     

QCM study of the adsorption of polyelectrolyte covered mesoporous TiO2 nanocontainers on SAM modified Au surfaces

Mesoporous TiO(2) nanocontainers (NCs) covered with polyelectrolyte multilayers were adsorbed on self-assembled monolayer (SAM) modified gold substrates at different values of pH and ionic strength. The adsorption process was followed in situ by means of a quartz crystal microbalance (QCM) and the morphology of the adsorbate was investigated by means of FE-SEM images taken of the substrates after each adsorption process. Deposition could be achieved if either the particles and the surface had opposite charge, or if the salt concentration was sufficiently high, reducing the repulsion between the spheres and the surface. In the latter case the adsorption kinetics could be explained in the context of the DLVO-theory. Using conditions of like charges, one has a means to control the speed of deposition by means of ionic strength. However, interparticle aggregation and cluster deposition on the surface were observed at high ionic strength. Such conditions have to be avoided to obtain a uniform deposition of separated nanocontainers on the surface.     

Mapping fragmental drug-likeness in the MoStBioDat environment: intramolecular hydrogen bonding motifs in β-ketoenols

A detailed knowledge of hydrogen bond geometry and its directional preferences is vital for in silico investigations of the ligand-receptor short-range non-covalent interactions. The spatial arrangement of the carbonyl and hydroxyl groups seems to determine the capability of β-ketoenol derivatives to recognize the surrounding environment by forming inter- and intra-molecular hydrogen bonds (IHB). In the current study we examined the application of the MoStBioDat platform for a massive database screening of the IHB motifs in β-ketoenol subunits (O=C-C=C-OH). Then, the virtual 3D structural data derived from ZINC and PubChem repository were compared to the experimentally determined CSD data. Differences specific for each database were discovered, which indicated inaccuracies in the simulated data.     

The influence of the carbon surface chemical composition on Dubinin-Astakhov equation parameters calculated from SF6 adsorption data-grand canonical Monte Carlo simulation

Using grand canonical Monte Carlo simulation we show, for the first time, the influence of the carbon porosity and surface oxidation on the parameters of the Dubinin-Astakhov (DA) adsorption isotherm equation. We conclude that upon carbon surface oxidation, the adsorption decreases for all carbons studied. Moreover, the parameters of the DA model depend on the number of surface oxygen groups. That is why in the case of carbons containing surface polar groups, SF(6) adsorption isotherm data cannot be used for characterization of the porosity.     

Collagen immobilization on 316L stainless steel surface with cathodic deposition of calcium phosphate

Collagen fibril/(calcium phosphate and carbonate) composite coatings on 316L stainless steel were developed with a cathodic deposition technique. The response of SaOS-2 osteoblast-like cells to the collagen/calcium salt-coated 316L steel was investigated. The collagen fibrils were self-assembled on the 316L steel surface and immobilized by their partial incorporation into a calcium salt layer electrodeposited cathodically in Hanks’ solution. The amount of calcium salt depended on the applied cathodic potential. The mineralization of collagen fibrils was observed. The collagen coverage localized and the composition of calcium salts varied on the same specimen. Such non-uniform surfaces affected the cell response. The observed outlines of cell bodies and nuclei on the thin collagen coating were clearer than those on the thick collagen coating in most cases. The collagen coating did not significantly influence the mean viability of cells on the whole specimen surface. Interestingly, the alkaline phosphatase activity per cell on the collagen/calcium salt-coated specimens was higher than that on the as-received specimen. It was revealed that cathodic deposition is an effective technique to immobilize collagen fibrils on a 316L steel surface.     

SEC ICP MS and CZE ICP MS investigation of medium and high molecular weight complexes formed by cadmium ions with phytochelatins

Size-exclusion chromatography (SEC) and capillary zone electrophoresis (CZE) coupled with inductively coupled plasma mass spectrometry were applied to characterize low, medium, and high molecular weight cadmium complexes with glutathione and phytochelatins (PCs). The dominant stoichiometry of the complexes formed in vitro was established as 1:1 using electrospray ionization mass spectrometry. Calculated molecular masses of Cd₁L₁ complexes were used for calibration of the SEC and CZE methods. The results showed a lower (2 kDa) SEC column exclusion limit for cadmium complexes compared with free peptides (10 kDa), and most of the high molecular weight cadmium species were eluted in the void volume of the column. Moreover, the CZE method based on the semiempirical model of Offord to elucidate peptide migration allowed us to show a high propensity of Cd–PC complexes for polymorphism on complexation, which was also observed for extracts of Arabidopsis thaliana treated with cadmium. All the information presented is vital for understanding the mechanism of metal deactivation in plants.

Development and validation method for the determination of selected tetracyclines in animal medicated feedingstuffs with the use of micellar liquid chromatography

A chromatographic procedure for the determination of oxytetracycline (OTC), tetracycline (TC), chlorotetracycline (CTC), and doxycycline (DC) in medicated feedingstuffs was developed. Samples were extracted with 0.01 M citric buffer/acetonitrile (pH 3.0) and further purified with 0.45 μm syringe filters. The purified extract was separated on Thermo column C₁₈, 150?×?4 mm, 5 μm and detection was carried out at 360 nm for OTC, and TC, 370 nm for CTC, and 350 nm for DC. TCs were eluted with a mobile phase of 0.03 M SDS/7 % 1-butanol/0.02 M oxalic acid/NaOH at pH 2.5. This method provided average recoveries of 80.4 % to 100.2 %, with CVs of 0.5 % to 6.6 % in the range of 50 to 1500 mg/kg OTC, TC, CTC, and DC in feeds. The linearity for the four TCs was determined by high-performance liquid chromatography-diode array detector (HPLC-DAD) in the range 10–300 μg/mL (50–1500 mg/kg), with a linear correlation coefficient (R)?>?0.99. The LOD and LOQ for TCs in pig and poultry feeds ranged from 4.0 to 10.7 and 4.7 to 12.6 mg/kg, respectively. The methodology was applied to the analysis of animal feedingstuffs collected from poultry and pig farms.

Redox Active Dipyrromethene?Cu(II) Monolayer for Oriented Immobilization of His‐Tagged RAGE Domains – the Base of Electrochemical Biosensor for Determination of Aβ16–23′

The new system which consists of the thiol derivative of dipyrromethene–Cu(II) complex created on the surface of a gold electrode was applied for the first time for oriented immobilization of selected His‐tagged domains of a receptor for advanced glycation endproducts (RAGE). Cyclic voltammetry (CV), Osteryoung square‐wave voltammetry (OSWV), electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM) were used for characterization of the redox active sensing layer. The biosensor proposed was applied for determination of Aβ_16–23′ peptide. In its presence, a decrease of the maximum Cu(II) redox current was observed. These values correlated linearly with the Aβ_16–23′ concentration in the range 0.001–1.000 µM. The presence of diluted human plasma has no influence on the sensor responses.     

Synthesis and Antibacterial Activity of Some New Derivatives of Thiosemicarbazide and 1,2,4-Triazole

Abstract

In a reaction of hydrazides of cyclohexylacetic acid 1 and phenylacetic acid 2 with isothiocyanates, respective thiosemicarbazide derivatives 3–18 were obtained. Further cyclization with 2% NaOH led to the formation of 5-(cyclohexylmethyl/benzyl)-4-substituted-2,4-dihydro-3H-1,2,4-triazole-3-thiones 19–34. Structures of all new products were confirmed by analytical and spectroscopic methods. All compounds were screened for their in vitro activity against some species of bacteria and fungi.

[Supplementary materials are available for this article. Go to the publisher's online edition ofPhosphorus, Sulfer, and Silicon and the Related Elements for the following free supplemental files: Additional figures and tables.]