On the use of response surface strategy to elucidate the electrophoretic migration of carbohydrates and optimize their separation

This paper focuses on the optimization with a design of experiments of a new CE method for the simultaneous separation of four carbohydrates of interest (fructose, glucose, lactose, and sucrose) and five potentially interfering carbohydrates (ribose, xylose, maltose, mannose, and galactose) with a highly alkaline separation electrolyte for subsequent applications to food, beverage, forensic, or pharmaceutical samples. First, the factors that potentially affect the carbohydrate migration were identified: NaOH concentration in the separation electrolyte, separation temperature, and separation electrolyte conductivity. A central composite design was then carried out to determine and model the effects of these three factors on normalized migration times and separation efficiency. From the model, an optimization of the separation was carried out using a desirability analysis based on resolutions between adjacent peaks and analysis time. The optimum conditions obtained were a separation electrolyte composed of 98 mM NaOH and 120 mM NaCl to adjust the conductivity at 4.29 S/m and a separation temperature fixed at 26.5°C. Finally, these conditions were experimentally confirmed and the robustness of the obtained separation was checked.     

A simple and efficient method to label l-fucose

This letter reports a new labeling method of fucoidan and more precisely of its monomer, l-fucose. We studied the coupling processes of new aryliodide precursors to l-fucose in order to prepare the next step, that is, the fucoidan radiolabeling. The use of precursors containing hydrazide and hydroxylamines is an alternative procedure avoiding the use of toxic borohydride or organic borane used for reductive amination. These coupling reactions are efficient and stereoselective. They provide stable products.     

A displacement assay for the sensing of protein interactions using sugar-tetraphenylethene conjugates

A displacement sensor array based on sugar-substituted tetraphenylethenes with the aggregation-induced emission feature for proteins to perform screening of protein-protein interactions is demonstrated.     

GC On-Line Profiling of Carbohydrate Esters in trans-Acidolysis reactions

A GC method has been developed for on-line profiling of reactants and products of a trans-acidolysis reaction between carbohydrate acetates and fatty acids. This method does not require the usual pre-column derivatization of the carbohydrates and it also circumvents the limitation of finding appropriate methods of detection in TLC and HPLC.     

A micropatterned carbohydrate display for tissue engineering by self-assembly of heparin

A novel strategy to construct a fibroblast scaffold on substrates has been demonstrated via top-down photolithography and the subsequent bottom-up processes of molecular self-assembly and molecular recognition. 3-Aminopropyltrimethoxysilane (APS) self-assembled monolayer was micropatterned by photolithography. An anionic polysaccharide heparin was adsorbed selectively on the cationic APS region of the micropatterned substrate. Basic fibroblast growth factor (bFGF) was selectively bound to the displayed heparin region and then micropatterned cultivation of fibroblast cells was successful on the bFGF-heparin-APS substrate.     

Glyco-Modification of Protein With O-Cyanate Chain-End Functionalized Glycopolymer via Isourea Bond Formation

Glycoengineering aimed at the addition of carbohydrates to proteins is an attractive approach to alter the pharmacokinetic properties of proteins, such as enhancing stability and prolonging the duration of action. We report a novel protein glyco-modification of BSA and recombinant thrombomodulin with O-cyanate chain-end functionalized glycopolymer via isourea bond formation. The protein glycoconjugates were confirmed by SDS-PAGE, western blot, and MALDI-TOF mass spectrometry. Protein C activation activity of the glyco-modified recombinant thrombomodulin was confirmed, proving no interference with activity from the glycopolymer modification. The isourea bond formation under mild conditions was demonstrated as an alternative method for protein modification with polymers.     

Solution and Solid‐State Polymerization of 2,3‐Dicyano‐5,7‐dimethyl‐6H‐1,4‐diazepine

Abstract

2,3‐Dicyano‐5,7‐dimethyl‐6H‐1,4‐diazepine (1) is polymerized to a conjugated structure in solution by both alkaline sugar reagents and butoxide in n‐butanol and in the solid state by thermal annealing. From both infrared and nuclear magnetic resonance spectra, all polymers have a similar chain repeat structure involving polymerization at one of the two cyano groups in the molecular structure of 1. Electronic spectra, gel permeation chromatography (GPC), and thermal analysis further characterize the polymers. The methyl protons of 1 are acidic, and solution polymerization is likely initiated by a delocalized anion derived from 1. This delocalized anion also provides a rationalization for polymerization at only one of the cyano groups of 1 instead of cyclopolymerization. The solid state polymerization leads to an amorphous product in a heterogeneous process. The crystal structure of 1 does not allow formation of an infinite chain. A tautomeric form of 1 likely initiates the solid state polymerization. The tautomerization creates a defect site in the crystal of 1, and the initial addition reaction is likely topochemical.     

Synthesis of Ganglioside Mimics for Binding Studies with Myelin‐Associated Glycoprotein (MAG)*

Glycosylation of 3‐O‐unprotected 2‐azido‐2‐deoxy‐galactopyranoside (compound 5) with O‐(2,3‐di‐O‐acyl‐4,6‐O‐benzylidene‐D‐galactopyranosyl) trichloroacetimidates (compounds 4A, B) as glycosyl donors afforded β (1–3)‐linked disaccharides (9A, B) in high yield. Removal of the 2,3‐O‐acyl groups and selective 3‐O‐alkylation with α‐benzyloxycarbonyl‐alkyl triflates furnished the protected target molecules, which could be readily transformed into the desired ganglioside mimics.     

H2SO4-SiO2: Highly Efficient and Reusable Catalyst for per-O-Acetylation of Carbohydrates Under Solvent-Free Conditions

Sulfuric acid immobilized on silica gel (H₂SO₄-SiO₂) was used as an efficient promoter for per-O-acetylation of carbohydrates with acetic anhydride under solvent-free conditions. The substrates include not only monosaccharides and disaccharides, but also glycosides. The catalyst is recyclable and stable at room temperature, and the reaction protocol is simple, is cost-effective, and gives good isolated yield with high purity. The large-scale reactions also proceeded conveniently and in high yields.