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Xyloglucan from tamarind seed has been submitted to an ultrasound treatment that reduces its molecular size to investigate the impact of molar mass on the interaction with cellulose. A low molar mass xyloglucan fraction (XGu, 1.04 × 10 5 g mol −1 ) was purified and its adsorption on the cellulose nanocrystal (CNC) surface has been investigated comparatively to the native fraction that presents high molar mass (XGn, 10.28 × 10 5 g mol −1 ). XGn arranged as loops and tails on CNCs whereas XGu formed trains onto the cellulose surface. Despite the extended conformation, XGu is able to cross-link cellulose nanocrystals in the layer-by-layer CNC-XG-CNC assemblies. Hydrolysis of model films by a xyloglucan-specific endoglucanase confirmed the greater accessibility of XGn loops and tails compared to the XGu trains. More importantly, in situ ellipsometry revealed that the presence of loops and tails facilitated swelling of CNC layers linked by XGn whereas the CNC-XGu-CNC structure did not experience swelling. [ABSTRACT FROM AUTHOR]

Chitinis a natural polymer of glucosamine bearing N-acetyl groups.Chitin nanocrystals (ChiNCs), resulting from the acid hydrolysis ofamorphous regions of chitin, are crystalline positively charged rod-likeparticles. ChiNCs show some interfacial properties and very efficientlystabilize oil/water interfaces, leading to the so-called Pickeringemulsions. In accordance with the irreversible adsorption of particles,these Pickering emulsions proved stable over time, with constant emulsionvolume for several months, even though natural creaming may occur.The emulsions produced are not clearly susceptible to ionic strengthor pH in terms of average droplet diameter. However, when mixed witha large amount of oil, high internal phase emulsions (HIPE) containingup to 96% of internal phase are formed as a gel with a texture thatcan be modulated from soft to solid gel by adjusting concentration,pH, and ionic strength. [ABSTRACT FROM AUTHOR]

Abstract: A novel class of complex oligosaccharides with a backbone made of twelve β-(1→4)-d-glucosyl units that may be regularly substituted on their primary position with α-d-xylosyl or β-d-(1→2)-galactosyl-α-d-xylosyl residues were readily synthesized using enzymatic hydrolysis of the plant polysaccharide xyloglucan (XG), followed by chemical modifications of the well-defined oligosaccharides and their enzymatic coupling catalyzed by the Cel7B E197A glycosynthase from Humicola insolens. These complex oligosaccharides proved useful for a better understanding of the effects of structural variation of xyloglucan on interactions with bacterial microcrystalline cellulose (BMCC). [Copyright &y& Elsevier]

A postassembly acid-treatment consisting of an immersion in 5 mM HCl solution was applied to carboxylated cellulose nanofibrils (CNF)-poly(allylamine) hydrochloride (PAH) multilayered thin films. Our results show that the treatment did not affect the overall thickness of the films without any loss of the components. However, a modification of the surface morphology was observed, as well as the swelling behavior. The process was perfectly reversible since the original structure was recovered when the thin films were rinsed by ultrapure water. Moreover, a more pronounced antireflective character was detected for the treated films. The origin of these reversible modifications was discussed. Notably, the scattering length density (SLD) profiles of the films before and after treatment support the idea of a structural reorganization of the components within the film driven by the change of their charge densities induced by the acid treatment. [ABSTRACT FROM AUTHOR]