Resonant Soft X-Ray Scattering of Cellulose Microstructure in Plant Cell Walls

Lignocellulose is the most abundant raw material for biofuels and the most important bio-renewable resource for building materials, paper, and textiles. A detailed understanding of the structure at the nano- and meso-scale could accelerate the development of an efficient biofuel conversion method. The plant cell wall is a heterogeneous mixture of various complex biopolymers including cellulose, hemicellulose, and pectin. The structure and assembly of these constituents in the plant cell wall is still not well understood. It is difficult to resolve the different elements through conventional hard X-ray scattering as they have similar electron density and hence, do not generate sufficient scattering contrast. The chemical specificity of resonant soft X-ray scattering (RSOXS) allows contrast to be generated based on differences in the chemistry of the different polysaccharides. By varying incident X-ray energies, we have achieved increased scattering contrast between cellulose and other polysaccharides from onions, such that features of the network structure of the cell wall are resolved. Thus, RSOXS reveals the packing distance of cellulose microfibrils embedded in the polysaccharide network.