A complex of oxidised chitosan and silver ions grafted to cotton fibres with bacteriostatic properties.

The laccase/TEMPO system was employed to oxidise the C6 primary hydroxyl group on the chitosan (CS) to form a carboxyl group to obtain oxidised chitosan (C-COS). The silver-oxidised chitosan complex(C-COS-Ag) was prepared by reacting C-COS with silver nitrate, then C-COS-Ag and cotton fibres were subjected to a reaction to prepare bacteriostatic fibres. FT-IR and XPS analysis showed that: Ag and C-COS were combined in these forms: Ag, [Ag(NH)] OH, -COOAg, and AgO.

The study of inhibitory effects and mechanism of carboxylate chitooligomer on melanin, prepared by laccase/TEMPO system.

A carboxylate chitooligomer (C-COS) containing carboxyl groups attached to chitooligomer (COS) molecules has been prepared by laccase/2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) system, which is a green-chemistry method. Several experiments were designed to evaluate inhibition effects on melanin and mechanisms of C-COS. The results indicated that C-COS exhibited more distinct anti-melanogenic effects compared to COS.

The hydration mechanism and hydrogen bonding structure of 6-carboxylate chitooligosaccharides superabsorbent material prepared by laccase/TEMPO oxidation system.

6-carboxylate chitooligosaccharides (6-CCOS), as a superabsorbent material, were prepared by way of the laccase/TEMPO oxidation system. It exhibited a higher moisture-absorption ability and stronger affinity for water. To understand the real reasons for this, the hydrogen bonding structure of 6-CCOS and the hydration mechanism of the molecule were investigated using infrared (IR), differential scanning calorimetry (DSC), and nuclear magnetic resonance (NMR).

Oxidation of primary hydroxyl groups in chitooligomer by a laccase-TEMPO system and physico-chemical characterisation of oxidation products.

The aim of this study was to investigate the oxidation of chitooligomer by a laccase-TEMPO system which had not previously been examined. Chitooligomer was treated with laccase and TEMPO in order to evaluate the potential of a laccase-TEMPO system to improve the moisture absorption, moisture retention, and antioxidant abilities of chitooligomer. Chitooligomer was prepared by degradation of high molecular weight chitosan with hydrogen peroxide followed by oxidation using a laccase-TEMPO system.

[Spectra analysis of lignin small molecular guaiacyl coniferyl alcohol biological modification treated by laccase].

The enzymatic modification mechanism of lignin small molecular lignin guaiacyl coniferyl alcohol existing in softwood and hardwood treated by laccase was studied. Gas chromatography-mass spectrometry (GC-MS), gel permeation chromatography (GPC), FTIR spectrum and PCD(particle charge detector) etc were used for the measurement. GC-MS could not detect the coniferyl alcohol monomer after treated by laccase, so it was speculated that coniferyl alcohol participated in the reaction totally, and the structure of coniferyl alcohol was changed.