Xyloglucans (XG) are a family of plant polysaccharides based on a highly xylose-substituted β-1,4-linked D-Glucopyranose-based backbone presenting high affinity for cellulosic surfaces. In plant cell walls, XG acts as cementing material that contributes to crosslinking and mechanical properties of the cellulose framework 1. Affinity of XG for cellulose has also been used to functionalize cellulose surface to create new materials 2. Adsorption of XG on many cellulose substrates have been largely documented, however on one hand most of research attempts to study the adsorption of XG at thermodynamic equilibrium neglect kinetic aspects of adsorption and on the other hand, the architecture of the XG-cellulose complexes remains largely unknown. In order to address these concerns, adsorption of xyloglucan onto cellulose nanocrystals (CNC) surfaces has been monitored by quartz crystal microbalance with dissipation (QCM-D) 3. The adsorption of XG did not result in the same final adsorption concentration, which evidenced a kinetically-controlled process. The presence of two adsorption regimes as a function of XG concentration was evidenced by fitting adsorption isotherms to a kinetic model comprising the contribution of adsorption onto uncovered CNC and the contribution of adsorption after XG rearrangement. For low XG concentrations, the kinetic constant for chain rearrangement is comparable to the kinetic constant for adsorption. For higher XG concentrations, the kinetic constant related to the conformational rearrangement decreases, indicating that XG molecules have no time to laterally rearrange before new XG molecules adsorb. This finding indicates that two organization can be reached according to the kinetics of adsorption and was confirmed by enzymatic degradation of the complexes revealing the occurrence of enzymatically accessible and inaccessible XG fractions 4. The proportion of XG loops and trains fraction adsorbed on the CNC surface is discussed in relation with adsorption process and underlying driving forces. 1 Hayashi, T.; Kaida, R. Molecular Plant 2011, 4 (1), 17-24. 2 Zhou, Q.; Rutland, M. W.; Teeri, T. T.; Brumer, H. Cellulose 2007, 14 (6), 625-641. 3 Villares, A.; Moreau, C.; Dammak, A.; Capron, I.; Cathala, B. Soft Matter 2015, 11 (32), 6472-6481. 4 Dammak, A.; Quemener, B.; Bonnin, E.; Alvarado, C.; Bouchet, B.; Villares, A.; Moreau, C.; Cathala, B. Biomacromolecules 2015, 16 (2), 589-596.

Exploration of xyloglucan-cellulose nanocrystal complexes architecture by kinetic adsorption studies and enzymatic susceptibility

251st National Meeting (2016)

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