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Poroelastic mechanical effects of hemicelluloses on cellulosic hydrogels under compression.

Lopez-Sanchez P, Cersosimo J, Wang D, Flanagan B, Stokes JR, Gidley MJ - PLoS ONE (2015)

Bottom Line: This behaviour could be explained considering the microstructure and the flow of water through the composites confirming their poroelastic nature.In contrast, small deformation oscillatory rheology showed that only xyloglucan decreased the elastic moduli.These results provide evidence for contrasting roles of different hemicelluloses in plant cell wall mechanics and man-made cellulose-based composite materials.

View Article: PubMed Central - PubMed

Affiliation: Australian Research Centre, Centre of Excellence in Plant Cell Walls, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Australia.

ABSTRACT
Hemicelluloses exhibit a range of interactions with cellulose, the mechanical consequences of which in plant cell walls are incompletely understood. We report the mechanical properties of cell wall analogues based on cellulose hydrogels to elucidate the contribution of xyloglucan or arabinoxylan as examples of two hemicelluloses displaying different interactions with cellulose. We subjected the hydrogels to mechanical pressures to emulate the compressive stresses experienced by cell walls in planta. Our results revealed that the presence of either hemicellulose increased the resistance to compression at fast strain rates. However, at slow strain rates, only xyloglucan increased composite strength. This behaviour could be explained considering the microstructure and the flow of water through the composites confirming their poroelastic nature. In contrast, small deformation oscillatory rheology showed that only xyloglucan decreased the elastic moduli. These results provide evidence for contrasting roles of different hemicelluloses in plant cell wall mechanics and man-made cellulose-based composite materials.

No MeSH data available.


Related in: MedlinePlus

13C CP/MAS spectra of a) C, b) CXG and c) CAX hydrogel composites.Uncompressed and compressed samples at 1μm/s and 100 μm/s. The peak for xylose C-1 in rigid xyloglucan can be seen at 99.5 ppm.
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pone.0122132.g002: 13C CP/MAS spectra of a) C, b) CXG and c) CAX hydrogel composites.Uncompressed and compressed samples at 1μm/s and 100 μm/s. The peak for xylose C-1 in rigid xyloglucan can be seen at 99.5 ppm.

Mentions: The presence of rigid segments of xyloglucan in CXG composites is indicated in Fig. 2 from the 13C CP/MAS NMR spectrum, which shows a peak at 99.5 ppm (Fig. 2B) due to the C-1 of xylose [31]. From integration of the xylose C-1 signal to the signal centred at 105 ppm due to cellulose C-1 and XG glucose and galactose C-1, the fraction of XG detected in the CP/MAS spectrum can be calculated to be 18% of the total composite or 48% of the XG (total XG is 37.5% of the composite). Xyloglucan but not cellulose is also observed in the 13C SP/MAS NMR spectrum that is attributable to mobile segments of xyloglucan. Thus the structure of CXG can be described as containing 18% rigid XG, 19.5% mobile XG and 62.5% (rigid) cellulose. The 13C CP/MAS spectrum of the CAX composite was indistinguishable from that of C (Fig. 2C). However, the 13C SP/MAS spectrum revealed 2 peaks in the C-1 region typical of arabinoxylan: xylose at 102.4 ppm and arabinose at 108.5 ppm. Therefore, although the AX is incorporated irreversibly within the composite, it retains internal mobility despite being associated with the surface of the cellulose scaffold.


Poroelastic mechanical effects of hemicelluloses on cellulosic hydrogels under compression.

Lopez-Sanchez P, Cersosimo J, Wang D, Flanagan B, Stokes JR, Gidley MJ - PLoS ONE (2015)

13C CP/MAS spectra of a) C, b) CXG and c) CAX hydrogel composites.Uncompressed and compressed samples at 1μm/s and 100 μm/s. The peak for xylose C-1 in rigid xyloglucan can be seen at 99.5 ppm.
© Copyright Policy
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4368770&req=5

pone.0122132.g002: 13C CP/MAS spectra of a) C, b) CXG and c) CAX hydrogel composites.Uncompressed and compressed samples at 1μm/s and 100 μm/s. The peak for xylose C-1 in rigid xyloglucan can be seen at 99.5 ppm.
Mentions: The presence of rigid segments of xyloglucan in CXG composites is indicated in Fig. 2 from the 13C CP/MAS NMR spectrum, which shows a peak at 99.5 ppm (Fig. 2B) due to the C-1 of xylose [31]. From integration of the xylose C-1 signal to the signal centred at 105 ppm due to cellulose C-1 and XG glucose and galactose C-1, the fraction of XG detected in the CP/MAS spectrum can be calculated to be 18% of the total composite or 48% of the XG (total XG is 37.5% of the composite). Xyloglucan but not cellulose is also observed in the 13C SP/MAS NMR spectrum that is attributable to mobile segments of xyloglucan. Thus the structure of CXG can be described as containing 18% rigid XG, 19.5% mobile XG and 62.5% (rigid) cellulose. The 13C CP/MAS spectrum of the CAX composite was indistinguishable from that of C (Fig. 2C). However, the 13C SP/MAS spectrum revealed 2 peaks in the C-1 region typical of arabinoxylan: xylose at 102.4 ppm and arabinose at 108.5 ppm. Therefore, although the AX is incorporated irreversibly within the composite, it retains internal mobility despite being associated with the surface of the cellulose scaffold.

Bottom Line: This behaviour could be explained considering the microstructure and the flow of water through the composites confirming their poroelastic nature.In contrast, small deformation oscillatory rheology showed that only xyloglucan decreased the elastic moduli.These results provide evidence for contrasting roles of different hemicelluloses in plant cell wall mechanics and man-made cellulose-based composite materials.

View Article: PubMed Central - PubMed

Affiliation: Australian Research Centre, Centre of Excellence in Plant Cell Walls, Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, Australia.

ABSTRACT
Hemicelluloses exhibit a range of interactions with cellulose, the mechanical consequences of which in plant cell walls are incompletely understood. We report the mechanical properties of cell wall analogues based on cellulose hydrogels to elucidate the contribution of xyloglucan or arabinoxylan as examples of two hemicelluloses displaying different interactions with cellulose. We subjected the hydrogels to mechanical pressures to emulate the compressive stresses experienced by cell walls in planta. Our results revealed that the presence of either hemicellulose increased the resistance to compression at fast strain rates. However, at slow strain rates, only xyloglucan increased composite strength. This behaviour could be explained considering the microstructure and the flow of water through the composites confirming their poroelastic nature. In contrast, small deformation oscillatory rheology showed that only xyloglucan decreased the elastic moduli. These results provide evidence for contrasting roles of different hemicelluloses in plant cell wall mechanics and man-made cellulose-based composite materials.

No MeSH data available.


Related in: MedlinePlus