A Versatile Method for Preparing Polysaccharide Conjugates via Thiol-Michael Addition

Polysaccharide conjugates are important renewable materials. If properly designed, they may for example be able to carry drugs, be proactive (e.g., with amino acid substituents) and can carry a charge. These aspects can be particularly useful for biomedical applications. Herein, we report a simple approach to preparing polysaccharide conjugates. Thiol-Michael additions can be mild, modular, and efficient, making them useful tools for post-modification and the tailoring of polysaccharide architecture. In this study, hydroxypropyl cellulose (HPC) and dextran (Dex) were modified by methacrylation. The resulting polysaccharide, bearing α,β-unsaturated esters with tunable DS (methacrylate), was reacted with various thiols, including 2-thioethylamine, cysteine, and thiol functional quaternary ammonium salt through thiol-Michael addition, affording functionalized conjugates. This click-like synthetic approach provided several advantages including a fast reaction rate, high conversion, and the use of water as a solvent. Among these polysaccharide conjugates, the ones bearing quaternary ammonium salts exhibited competitive antimicrobial performance, as supported by a minimum inhibitory concentration (MIC) study and tracked by SEM characterization. Overall, this methodology provides a versatile route to polysaccharide conjugates with diverse functionalities, enabling applications such as antimicrobial activity, gene or drug delivery, and biomimicry.

Synthesis of a MnO2/Fe3O4/diatomite nanocomposite as an efficient heterogeneous Fenton-like catalyst for methylene blue degradation

Heterogeneous Fenton-like catalysts with the activation of peroxymonosulfate (PMS), which offer the advantages of fast reaction rate, wide functional pH range and cost efficiency, have attracted great interest in wastewater treatment. In this study, a novel magnetic MnO2/Fe3O4/diatomite nanocomposite is synthesized and then used as heterogeneous Fenton-like catalyst to degrade the organic pollutant methylene blue (MB) with the activation of PMS. The characterization results show that the Fe3O4 nanoparticles and nanoflower-like MnO2 are evenly distributed layer-by-layer on the surface of diatomite, which can be readily magnetically separated from the solution. The as-prepared catalyst, compared with other Fenton-like catalysts, shows a superb MB degradation rate of nearly 100% in 45 min in the pH range of 4 to 8 and temperature range of 25 to 55 °C. Moreover, the nanocomposite shows a good mineralization rate of about 60% in 60 min and great recyclability with a recycle efficiency of 86.78% after five runs for MB. The probable mechanism of this catalytic system is also proposed as a synergistic effect between MnO2 and Fe3O4.

Non-classical hydrogen bond triggered strand displacement for analytical applications and DNA nanostructure assembly

A novel strand displacement triggered by the non-classical hydrogen bond between cyanuric acid and adenine exhibits a fast reaction rate.

Synthesis and in vitro anti breast cancer activity of some novel 1,5-benzothiazepine derivatives

The title compounds 3a-j, substituted 1,5-benzothiazepines were synthesized by the condensation of variously substituted chalcones 1 and 2- aminothiophenol 2 via conventional as well as non-conventional inorganic solid support microwave irradiation methods. The non-conventional protocol offers several advantages such as simple procedure, fast reaction rate, mild reaction conditions and improved yields compared to conventional methods. The structures of the products 3a-j were established by elemental analysis, FTIR, 1H-NMR, 13C-NMR and mass spectroscopic studies. The synthesized compounds have also been evaluated for the cytotoxicity against human breast cancer cell line MDA-MB-435 with some exhibiting in vitro anti-breast cancer activities.

A Study Numerical Simulation of Post Combustion CO2 Capture Process

Amine absorption technology, in particular that based on the Monoethanolamine (MEA) process, is considered to be viable for low pressure flue gas CO2 capture because of the MEA-CO2 fast reaction rate. MEA absorption processes are associated with high capital and operating cost because a significant amount of energy is required for solvent regeneration and severe operating problems are present such as corrosion and solvent loss and degradation. The overall objective of this study is to evaluate the feasibility of obtaining the heat required for amine absorption for a particular recovery of carbon dioxide. Comparisons among cases were performed to determine the best operating conditions for CO2 capture. An analysis of the lean loading and recovery percent were carried out as well as the different absorber and stripper combinations by using the chemical processes simulator.

Measurement of Hexoses and Pentoses, Singly or in Combination, with o-Anisidine

Hexoses and pentoses can be measured either singly or in combination, with an o-anisidine reagent. It has the advantages of a fast reaction rate and relatively little interference from hexoses (Amax = 660 nm) in the measurement of pentoses. A simple subtraction of absorbance attributable to glucose at the maximum for pentoses (465 nm) is sufficient for satisfactory pentose estimation in urine. The method has been automated, and results compare favorably with those from an automated procedure for the measurement of serum glucose in which hexokinase is used, and also with those from a colorimetric aniline method for measurement of pentoses in urine. Interferences and procedural variables are discussed. Urinary pentose and hexose values for normal infants are reported.