Application of nickel phosphate nanoparticles and VSB-5 in the modification of carbon paste electrode for electrocatalytic oxidation of methanol

Carbon paste electrodes were modified by nickel phosphate nanoparticles and nickel phosphate Versailles Santa Barbara-5 molecular sieves. Then, transition metal ions of Ni(II) were incorporated to the nickel phosphate by immersion of the modified electrode in a 0.1-M nickel chloride solution. The electrochemical behaviors of the modified electrodes were studied using cyclic voltammetry. These modified electrodes were used as anode for the electrocatalytic oxidation of methanol in alkaline medium. The influence of some parameters such as different molecular sieves, scan rate of potential, and methanol concentration was investigated on the anodic peak height of the methanol oxidation. The best result was obtained by nickel phosphate nanoparticles.     

REACTIONS WITH 2-THIOHYDANTOIN DERIVATIVES: SYNTHESIS OF MANNICH BASES AND IMIDAZOTHIAZOLE DERIVATIVES

Abstract

5-Arylidene-2-thiohydantoins (la-c) and 5-arylazo-1-phenyl-2-thiohydantoins (7a, b) were condensed with formaldehyde and primary or secondary aromatic amines to give the corresponding Mannich bases (2a-f) and (8a, b) respectively, which could also be converted into the educts (la-c) and (7a, b) by boiling in ethanolic HCI. On treatment of (2a-f), (5a-c) and (8a, b) with an ethereal diazomethane the colourless cyclopropane products (3a-c) and yellow N-methyl substituted compounds (9, b) were isolated respectively. Alkylation of (2d-f) with methyl iodide and (la-e) with 3-chloropentane-2,4 dione gave the corresponding 2-alkylmercapto derivatives (5a-c) and (2a-c) respectively, the former of which on hydrolysis by boiling ethanolic HCI afforded the hydantoin derivatives (6a-c). Cyclization of (12a-c) using polyphosphoric acid resulted in the formation of imidazothiazole derivatives (13a-c). The structure of the isolated products were established by elemental analyses and spectral data studies.     

Enhanced Maturation of 3D Bioprinted Skeletal Muscle Tissue Constructs Encapsulating Soluble Factor-Releasing Microparticles

Several microfabrication technologies have been used to engineer native-like skeletal muscle tissues. However, the successful development of muscle remains a significant challenge in the tissue engineering field. Muscle tissue engineering aims to combine muscle precursor cells aligned within a highly organized 3D structure and biological factors crucial to support cell differentiation and maturation into functional myotubes and myofibers. In this study, the use of 3D bioprinting is proposed for the fabrication of muscle tissues using gelatin methacryloyl (GelMA) incorporating sustained insulin-like growth factor-1 (IGF-1)-releasing microparticles and myoblast cells. This study hypothesizes that functional and mature myotubes will be obtained more efficiently using a bioink that can release IGF-1 sustainably for in vitro muscle engineering. Synthesized microfluidic-assisted polymeric microparticles demonstrate successful adsorption of IGF-1 and sustained release of IGF-1 at physiological pH for at least 21 days. Incorporating the IGF-1-releasing microparticles in the GelMA bioink assisted in promoting the alignment of myoblasts and differentiation into myotubes. Furthermore, the myotubes show spontaneous contraction in the muscle constructs bioprinted with IGF-1-releasing bioink. The proposed bioprinting strategy aims to improve the development of new therapies applied to the regeneration and maturation of muscle tissues.     

The Effect of Different Ethoxylations for Sorbitan Monolaurate on Enhancing Simultaneous Saccharification and Fermentation (SSF) of Wheat Straw to Ethanol

In this paper, four nonionic surfactants with different hydrophilic–lipophilic balance (HLB) based on sorbitan monolaurate were synthesized by introducing ethylene oxide gas (n = 20, 40, 60, and 80 ethylene oxide units). The chemical structure of the prepared ethoxylated surfactants was confirmed using Fourier transform-infrared and ¹H NMR spectroscopes. The surface tension and thermodynamic properties of the prepared surfactants have been studied. The simultaneous saccharification and fermentation (SSF) process for ethanol production from microwave/alkali pretreated wheat straw has been assayed using nonionic surfactants have different ethylene oxide units. Ethanol yield was 82% and 61% for Kluyveromyces marxianus and Saccharomyces cerevisiae, respectively, with the addition of 2.5 g/l of the prepared nonionic surfactant (HLB = 18.2). Results show that the production of ethanol from microwave/alkali pretreated wheat straw increased with increasing the (HLB) value of the nonionic surfactant.     

The Effect of Chemical Modification with Pyromellitic Anhydride on Structure, Function, and Thermal Stability of Horseradish Peroxidase

The stability of enzymes remains a critical issue in biotechnology. Compared with the strategies for obtaining stable enzymes, chemical modification is a simple and effective technique. In the present study, chemical modification of horseradish peroxidase (HRP) was carried out with pyromellitic anhydride. HRP has achieved a prominent position in the pharmaceutical, chemical, and biotechnological industries. In this study, the effect of chemical modification on thermal stability, structure, and function of the enzyme was studied by fluorescence, circular dichroism, and absorbance measurements. The results indicated a decrease in compactness of the structure and a considerable enhancement in thermal stability of HRP below 60?°C. It seems the charge replacement and introduction of the bulky group bring about the observed structural and the functional changes.     

Spectrofluorimetric determination of drugs containing active methylene group using N1-methyl nicotinamide chloride as a fluorigenic agent

A spectrofluorimetric method was described for the determination of drugs containing active methylene groups adjacent to carbonyl groups. The method was applied successfully to the determination of three life saving cardiovascular drugs, with narrow therapeutic indices: pentoxifylline (I), propafenone hydrochloride (II) and acebutolol hydrochloride (III), in laboratory-prepared mixtures, in commercial tablets and in plasma samples. The method involved the reaction of each of the tested drugs with N1-methyl nicotinamide chloride (NMNCl) in the presence of alkali, followed by addition of formic acid, where highly fluorescent reaction products were produced. The produced fluorescence were measured quantitatively at 472 nm (lambdaex 352 nm), 409 nm (lambdaex 310 nm) and 451 nm (lambdaex 266 nm) for (I), (II), and (III) respectively. The method was linear over concentration ranges of 10-1000 microg/ml , 0.2-12 microg/ml and 0.08-10 microg/ml in standard solutions for (I), (II), and (III) respectively. In spiked human plasma samples, calibration graphs were linear over concentration ranges of 20-1000 microg/ml, 0.2-15 microg/ml and 0.08-10 microg/ml for (I), (II), and (III) respectively. The method showed good accuracy, specificity and precision in both laboratory-prepared mixtures and spiked human plasma samples. The proposed method is simple, with low instrumentation requirements, suitable for quality control application, bioavailability and bioequivalency studies.     

Sodium Phytate-Incorporated Gelatin-Silicate Nanoplatelet Composites for Enhanced Cohesion and Hemostatic Function of Shear-Thinning Biomaterials

Shear-thinning biomaterials (STBs) based on gelatin-silicate nanoplatelets (SNs) are emerging as an alternative to conventional coiling and clipping techniques in the treatment of vascular anomalies. Improvements in the cohesion of STB hydrogels pave the way toward their translational application in minimally invasive therapies such as endovascular embolization repair. In the present study, sodium phytate (Phyt) additives are used to tune the electrostatic network of SNs-gelatin STBs, thereby promoting their mechanical integrity and facilitating injectability through standard catheters. We show that an optimized amount of Phyt enhances storage modulus by approximately one order of magnitude and reduces injection force by ≈58% without compromising biocompatibility and hydrogel wet stability. The Phyt additives are found to decrease the immune responses induced by SNs. In vitro embolization experiments suggest a significantly lower rate of failure in Phyt-incorporated STBs than in control groups. Furthermore, the addition of Phyt leads to accelerated blood coagulation (reduces clotting time by ≈45% compared to controls) due to the contributions of negatively charged phosphate groups, which aid in the prolonged durability of STB in coagulopathic patients. Therefore, the proposed approach is an effective method for the design of robust and injectable STBs for minimally invasive treatment of vascular malformations.