Cell wall polysaccharides from Gelidium species: physico-chemical studies using MRI techniques

Magnetic resonance imaging (MRI) has already been successively used to inve stigate polysaccharide matrices. In particular, MRI at microscopic resoluti on (MR microscopy) is now one of the most powerful techniques for studying the physical properties of natural hydrogels. To contribute to a better und erstanding of the correlation between chemical and physical properties of a gar gels,we report here the measurement of the water magnetic parameters fo r agar gels extracted from different species of Gelidium: T-1 and T-2 relax ation times, magnetisation transfer (M-s/M-0) and diffusion (D) were measur ed to evaluate their use for studying the gel characteristics. MR microscop ic images were acquired at 7.05 Tesla using various pulse sequences. The re sults obtained confirmed the possibility to use quantitative MRI for the ch aracterisation of physical parameters correlated with the type of agar chem ical structure. In particular, T-2 data obtained for gels at different conc entrations indicate that this magnetic parameter is very sensitive to the a gar concentration and hence particularly useful for the gel strength determ ination.