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In this study, cross-linked chitosan microspheres (CCTS) was synthesized from chitosan and epichlorohydrin (ECH), then, 2-(chloromethyl) benzimidazole (CBM) was introduced to modify CCTS as the ligand. The resulting CBM-chitosan was characterized by EA, FTIR and TGA, and tested for metal adsorption. Results showed that CBM-chitosan has a relatively high selectivity toward Hg(2+). Equilibrium data were fitted well with Langmuir isotherms with the maximum adsorption capacity of 257.8 mg/g for Hg(2+). Both kinetics and thermodynamic parameters of the adsorption process were obtained. The data indicated that adsorption process was exothermic spontaneous reaction and kinetically proceeded according to Second-order kinetics model. CBM-chitosan can be eluted effectively using 1.0 mol/L HCl solution and it has a potential use for separation and preconcentration of Hg(2+) ions from contaminated natural waters., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The MCTS‐g‐AT was developed as a novel magnetic adsorbent with core‐shell structure. Its unique synthesis route endows MCTS‐g‐AT with green, convenient, economical and safe characteristics, and also good selective adsorption of Hg(II). The material was characterized using an appropriate set of spectroscopic and analytical techniques (SEM, EDS, XRD, VSM, FTIR, and TGA). Its adsorption kinetics fits the pseudo‐secondary model well and adsorption isotherm fits the Langmuir equation well, suggesting the mechanism of chemisorption with monolayer adsorption. The results of the thermodynamic parameters indicate spontaneous and endothermic process. Column adsorption experiments showed that the maximum adsorption capacity of Hg(II) was 207.6 mg/g (298 K). Moreover, the Hg(II) adsorbed on composite microspheres was completely eluted by 3 mol/L HNO3 or 4 mol/L HCl. Furthermore, MCTS‐g‐AT adsorption column combined with spectrophotometer can achieve more accurate detection of Hg(II) in aquatic products. [ABSTRACT FROM AUTHOR]

Objectives The goal of this study was to evaluate the modulatory effect of chitosan oligosaccharide-nisin conjugate (CON-C) on intestinal microbiota of human flora-associated (HFA) mice and also reveal its effect towards the high-fat diet (HFD)-induced obesity. Both Chitosan oligosaccharides and nisin showed great potential in modulating the intestinal microbiota, so it is worth to explore whether the modulation effect of chitosan oligosaccharide could be improved by covalently binding with nisin. Materials and Methods CON-C was prepared by heating the mixed solution of chitosan oligosaccharide and nisin at 80°C and pH 2.0 for 24h. The structure of CON-C were analyzed by Fourier transform-infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The CON-C's anti-obesity effect and modulatory effect toward intestinal microbiota were analyzed using human flora-associated (HFA) mice model. Results CON-C could alleviated HFD-induced gut dysbiosis, by significantly decreasing the numbers of Bifidobacterium and Lactobacillus/Enterococcus spp. and increasing the numbers of Bacteroides–Prevotella and Clostridium groups. CON-C could also enriched the most differentially expressed genes through KEGG pathways of biosynthesis of amino acids, two-component system, and ATP binding cassette (ABC) transporters. Conclusions The improved therapeutic effect of CON-C against HFD-induced obesity has been approved, and hence, CON-C has a great potential to be utilized as a functional food ingredient in reducing body weight. [ABSTRACT FROM AUTHOR]

In this study, a unique carrier magnetic chitosan microspheres (MCTS) was simply synthesized by anchoring Fe3O4onto chitosan for direct immobilization of cellulases cross-linked by gluteraldehye. The structure and morphology were characterized using FT-IR, TGA, VSM and SEM. The optimum immobilization conditions were investigated: immobilized pH 7.0, amount of enzyme 15 mL (0.1 mg/mL), immobilization temperature 30 °C, immobilization time 5 h. At optimum conditions, MCTS achieved maximum enzyme solid loading rate of 73.5 mg/g, while recovery of enzyme activity approached to 71.6%. In the recycle test, immobilized cellulases operated without significant loss in its initial performances after 3 cycles, which indicated that immobilized cellulases can be regenerated and reused. The immobilized enzyme has better values of thermal and storage stability than that of free enzyme. Therefore, MCTS may be considered as a candidate with potential value of application in large-scale operations for cellulases immobilization. [ABSTRACT FROM PUBLISHER]

Highlights: [•] The chelating cross-linked chitosan (CBM-chitosan) is a novel adsorption material. [•] 2-(Chloromethyl) benzimidazole was first connected to cross-linked chitosan. [•] CBM-chitosan shows high selectivity and good adsorption capacity toward Hg2+. [•] CBM-chitosan can be eluted effectively and has satisfactory reusability. [•] CBM-chitosan is a potential biosorbent for Hg2+ analysis, removal and recovery. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of chitosan oligosaccharides (COS)–nisin conjugates (COS‐N CON) on the quality changes of Collichthys niveatus during storage at 4°C. COS–N CON were prepared by heating the aqueous solution of COS and nisin together at 80°C for 24 hr. In order to control the degree of conjugation, the total concentration and pH of mixed solution were adjusted to 2% and 2.00, respectively. COS–N CON were identified by Fourier transform infrared (FT–IR) and X–ray diffraction analysis (XRD). During storage, COS–N CON treated samples showed retarded sensory and texture deterioration, with significantly slower increase rate of pH, total viable counts (TVC), and total volatile basic nitrogen (TVB–N). At the day 6, the TVC, TVB–N, and hardness of C. niveatus treated with distilled water reached 6 log10(CFU/g), 28 mg/100 g, and 15 g, respectively; while that in COS–N CON treated samples was 5.1 log10(CFU/g), 21 mg/100 g, and 18 g, respectively. Based on indicating parameters tested, it was revealed that the COS–N CON treatment could prolong the shelf life of C. niveatus by 2 days during chilled storage, compared to the chitosan oligosaccharides (COS)–nisin mixture (COS–N MIX). Practical applications: The novel preservation agent we created in this study could be considered as safe and renewable, which could be a great advantage in practical application. It was formed by conjugating chitosan oligosaccharides (COS) with nisin via Maillard reaction. Both COS and nisin were considered as green and renewable antimicrobial agents. Maillard reaction is one of the main reactions taking place in food that does not need catalyst and organic solvent. COS–nisin conjugates had a better effect on preservation of Collichthys niveatus, compared with COS–nisin mixtures, which indicating Maillard reaction could be the effective way in modifying the preservation properties of natural antimicrobial agents. [ABSTRACT FROM AUTHOR]