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关键词： Transition metal complexes   EPR   Drug resistance   Diabetes   Ligand-protein interaction   Fluorescence spectroscopy  

摘要： Two major health crisis of today's world are antimicrobial drug resistance and type II diabetes. To tackle them, there is an immediate requirement for the development of new and safer drugs and the present work is one such quest for novel and efficient drug candidates. We have developed three trace metal coordination compounds tethered with a reduced salen ligand {H-2(hpdbal)(2)-an} (L), namely, a manganese-salan complex, [Mn-II(H2O)(2){(hpdbal)(2)-an}] (1), a nickel-salan complex, [Ni-II{(hpdbal)(2)-an}] (2) and a copper-salan complex, [Cu-II{(hpdbal)(2)-an}] (3). The compounds were characterized by elemental analysis, vibrational spectroscopy, electronic spectroscopy, thermogravimetric analysis, nuclear magnetic resonance and electron-paramagnetic resonance techniques. The compounds were evaluated for antimicrobial activity against seven pathogens (Escherichia coli, Klebsiella pneumonia, Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Cryptococcus neoformans) and antidiabetic activity by mimicking diabetic environment on the immortal human liver cancer cells, HepG2. Complexes 1 and 2 were additionally tested for their reactivity and stability in biological media mimic conditions. The nickel(II) salan complex (2) exhibited noteworthy anti fungal activity against Candida albicans and the manganese(II) salan complex (1) induced increased glucose uptake by the insulin resistant cells. Both compounds were found to be stable when solution pH conditions were varied from 3 to 9. They exhibited strong affinity of binding towards a carrier protein, bovine serum albumin which was evaluated with the aid of multi-spectroscopic techniques. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Neural networks   Physical chemistry   Peptides and proteins   Molecular modeling   Machine learning  

关键词： Sensitivity   Gas sensor   Nanocomposite   Dielectric permittivity   a.c. conductivity  

摘要： The aim of this article is to investigate the effect of concentration of SiC on structural, optical, dielectric and gas sensing properties of CoFe₂O₄/SiC nanocomposites. For this purpose, CoFe₂O₄/SiC nanocomposites were synthesized using chemical co-precipitation method with different (10, 20 and 30) wt% of SiC. The structural, optical, dielectric and morphological properties were investigated using X-ray diffractometer, UV-Vis spectroscopy, LCR meter and SEM respectively. The average crystallite size of CFO (CoFe₂O₄) and CFO/SiC nanocomposites of 10, 20 and 30 wt% was estimated to be 9.3 ±2nm, 9.3 ±2nm, 9.2 ±2nm and 12.6 ±3nm, respectively using Scherrer’s formula. The energy band gap was found in the range from 4.1eV to 4.5eV for all synthesized samples. The dramatic behavior was observed in dielectric permittivity, dissipation factor and a.c. conductivity with varying frequency and temperature. The dielectric permittivity, dissipation factor, a.c. conductivity and sensitivity (%) towards NH₃ gas for 20 wt% of CFO/SiC nanocomposites were observed greater than other wt%. The compactness and porosity of device were determined by micrographs.

关键词： Cadmium (II) dibromide L- proline monohydrate   Crystal structure   Rietveld refinement   Dubious crystal  

摘要： The authors of the title paper (J. Mol Struc. 1204 (2020) 127,457) claim to have grown a so-called 'Cadmium (II) dibromide LProline monohydrate' (CBLPM) crystal by the slow evaporation method and studied its crystal structure by Rietveld refinement technique. In this comment, many points of criticism, concerning the crystal growth, Rietveld refinement, spectra and theoretical study of the so called CBLPM crystal are highlighted. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Neural networks   Physical chemistry   Peptides and proteins   Molecular modeling   Machine learning  

关键词： Neural networks   Physical chemistry   Peptides and proteins   Molecular modeling   Machine learning  

关键词： SPI   in vitro digestion process   protein oxidation   digestion behavior   microstructure  

摘要： The effects of oxidation on the gastric digestion properties of soybean protein isolates (SPIs) in a model of lipoxygenase (LOX)-catalyzed linoleic acid (LA) oxidation system and the multiscale structural characterization of SPI hydrolysate were investigated. Results indicated that the feature of SPI hydrolysate is dependent upon the degree of oxidation. Pepsin hydrolysis caused a red shift in fluorescence intensity and a reduction in surface hydrophobicity and diminished the particle size of SPI hydrolysate during gastric digestion. Compared with the control, mild oxidation was beneficial to protein unfolding and gastric digestibility, as manifested by minimal molecular weight (MW) distribution >50 kDa (32.34%) and smaller peptide fragments under scanning electron microscopy. However, severe oxidation brought about 39.47% loss of free amino acids. It was interesting to find that glycinin was more vulnerable to pepsin hydrolysis after oxidation as compared to the native SPI. Overall, the moderately oxidized SPI appeared to be digested to a greater extent.

关键词： Gelatin   Graphene oxide   Gelatin-GO aerogels   Microwave-assisted synthesis  

摘要： Gelatin aerogels reinforced with graphene oxide (GO) at different pH values of GO and Gelatin:GO ratios were developed by microwave (MW)-assisted synthesis. The chemical characterization demonstrated noncovalent and covalent interactions under acidic and alkaline conditions, respectively. The elastic modulus increased 6 times and 1.38-fold, and the swelling ratio (SR) increased 1.2-fold and 1.4 times for aerogels at acidic and alkaline pH, respectively, when the gelatin content increased. The surface charge shifted from positive to negative values by increasing the pH. Additionally, a higher SR value was found for the aerogel synthesized in alkaline environment and lowest Gelatin:GO ratio, and its properties were compared to an aerogel synthesized by traditional processes to validate the MW as synthesis method. Similar physicochemical properties were identified in both aemgels, with an increase in the SR value for the MW synthetized aemgel of 1.5 times. This study provides a new synthesis method to develop gelatin-GO aerogels.

关键词： Vesicles   Lipids   Molecules   Membranes   Monolayers  

摘要： We have designed and synthesized new short lipopeptides composed of tetrapeptide conjugated to fatty acids with different chain lengths. The amino acid sequence of the peptide moiety included D-phenylalanine, two residues of L-2,4-diaminobutyric acid and L-leucine. To explore the possible mechanism of lipopeptide action, we have provided a physicochemical characterization of their interactions with artificial lipid membranes. For this purpose, we have used monolayers and bilayers composed of lipids representative of Gram-negative and Gram-positive bacterial membranes. Using surface pressure measurements and atomic force microscopy, we were able to monitor the changes occurring within the films upon exposure to lipopeptides. Our experiments revealed that all lipopeptides can penetrate the lipid membranes and affect their molecular ordering. The latter results in membrane thinning and fluidization. However, the effect is stronger in the lipid films mimicking Gram-positive bacterial membranes. The results of the physicochemical characterization were compared with the biological activity of lipopeptides. The effect of lipopeptides on bacterial growth was tested on several strains of bacteria. It was revealed that lipopeptides show stronger antimicrobial activity against Gram-positive bacteria. At the same time, all tested compounds display relatively low hemolytic activity.

关键词： biodegradable microspheres   controlled-release   peptide delivery   peptide-polymer interactions   PLGA  

摘要： Sandostatin LAR (SLAR) is an injectable long-acting release (LAR) microsphere formulation for octreotide based on a biodegradeable glucose star copolymer of D,L-lactic and glycolic acids (PLGA-glu), which is primarily used for the treatment of patients with acromegaly. There currently is no generic SLAR approved in the United States despite expiration of patent coverage. To understand better this important formulation, SLAR was assessed for its composition and physical-chemical properties. Octreotide release kinetics was monitored under physiological conditions over 56 days together with several bioerosion parameters [mass loss, water uptake, pH of release media, polymer molecular weight (Mw), and confocal microscopy after BODIPY uptake]. A significant increase in the amount of released peptide occurred after day 14. After 1 day of incubation in PBST, octreotide was not extractable completely from SLAR during 2 h of the extraction process, but complete extraction was accomplished after 24 h, which suggested that strong and noncovalent PLGA-octreotide interactions occurred beginning in the initial release phase. Leuprolide is considered as a cationic peptide competitor for octreotide-PLGA interactions and its presence in the release medium resulted in more continuous octreotide release from SLAR, which was linearly correlated with the mass loss from the polymer (i.e., an indication of erosion-controlled release). These data strongly suggest that octreotide forms a salt with acid end groups of linear PLGA chains that are either present as impurities in, and/or produced by the degradation of, the PLGA-Glu. This salt is expected to catalyze octreotide acylation and extend peptide release beyond that driven by erosion control. The characterization studies of physicochemical properties of SLAR described here could be useful for the development and regulatory evaluation of generic octreotide microspheres as well as new polymer formulations, in which the polymer strongly in