Pectins: structure, biosynthesis, and oligogalacturonide-related signaling.

This review concerns the applications of some polysaccharides in the domain of biomaterials and bioactive polymers. Natural polysaccharides from different sources have been studied for a long time, and their main properties are summarized in this paper; some of their derivatives obtained by chemical modification are also described. The main polysaccharides currently used in the biomedical and pharmaceutical domains are chitin and its derivative chitosan, hyaluronan and alginates. Alginates are well known for their property of forming a physical gel in the presence of divalent counterions (Ca, Ba, Sr) whereas carrageenans form a thermoreversible gel; these seaweed polysaccharides are mainly used to encapsulate different materials (cells, bacteria, fungi). Other promising systems are the electrostatic complexes formed when an anionic polysaccharide is mixed with a cationic polysaccharide (e.g. alginate/chitosan or hyaluronan/chitosan). An important development of the applications of polysaccharides can be predicted for the next few years in relation to their intrinsic properties such as biocompatibility and biodegradability in the human body for some of them; they are also renewable and have interesting physical properties (film-forming, gelling and thickening properties). In addition, they are easily processed in different forms such as beads, films, capsules and fibres. Copyright © 2007 Society of Chemical Industry

Main properties and current applications of some polysaccharides as biomaterials

Hyaluronan : preparation, structure, properties, and applications

Determination of pectin degree of esterification by diffuse reflectance Fourier transform infrared spectroscopy

Composition, structure and thermal degradation of hemp cellulose after chemical treatments

Identification et caractérisation des précurseurs biologiques des carraghénanes par spectroscopie de r.m.n.-13C

The quantitative analysis of uronic acid polymers by infrared spectroscopy.

Complete assignments are given for the 13C NMR spectra of hyaluronate and chondroitin in deuterium oxide solution at 50.32 MHz. The assignments published earlier for chondroitin 6-sulphate and chondroitin 4-sulphate were largely confirmed but were found to need some revision in detail. Our conclusions for hyaluronate and the chondroitin sulphates were confirmed by off-resonance experiments based on the proton NMR assignments.



The spectra for hyaluronate show line narrowing and chemical shift changes from neutral to alkaline solution which are consistent with, and clearer than, the effects reported earlier for the proton spectra. As before no such changes occur for the chondroitin sulphates. The suggested interpretation is in terms of a conformation change for hyaluronate which originates mainly in altered interaction energies across the 1 3 linkage with the results that motional freedom is enhanced above that of the parent hyaluronate and even above the chondroitin sulphates. This, and the evidence from a temperature effect, suggests that an additional potential energy minimum is made favourable in alkali so that the overall amplitudes of the bond oscillations are increased.

David Welti

Papers

Identification et caractérisation des précurseurs biologiques des carraghénanes par spectroscopie de r.m.n.-13C

The quantitative analysis of uronic acid polymers by infrared spectroscopy.

The 13C‐NMR Spectra of Hyaluronate and Chondroitin Sulphates

The 13C-n.m.r. spectra of (1→6)-α-d-galactosyl-(1→4)-β-d-mannans