Unravelling a Direct Role for Polysaccharide β‐Strands in the Higher Order Structure of Physical Hydrogels

Abstract

The mechanical properties of agarose-derived hydrogels depend on the scaffolding of the polysaccharide network. To identify and quantify such higher order structure, we applied Raman optical activity (ROA)-a spectroscopic technique that is highly sensitive towardc arbohydrates-on native agarose and chemically modified agarose in the gel phase for the first time.B ys pectral global fitting,w ei solated features that change as af unction of backbone carboxylation (28, 40, 50, 60, 80, and 93 %) from other features that remain unchanged. We assigned these spectral features by comparison to ROAs pectra calculated for different oligomer models.W e found a6 0:40 ratio of double-and single-stranded a-helix in the highly rigid hydrogel of native agarose,w hile the considerably softer hydrogels made from carboxylated agarose use ascaffold of unpaired b-strands.Water swollen cross-linked polymer networks, [1] otherwise known as hydrogels,h ave found extensive applications in consumer products, [2] pharmaceuticals, [1,3] regenerative medicine, [2,4] and microfluidics devices. [5] Then etwork formation in hydrogels involves covalent, ionic, or physical crosslinks between polymer chains. [1] Then ature of the crosslinks can impact many important properties of the gel, such as stiffness, porosity,a nd rheology.H ydrogels formed from agarose, Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: http://dx.

Solution Structure of Mannobioses Unravelled by Means of Raman Optical Activity

“…From these results, we show that the vibrational modes of the investigated mannose disaccharides are highly delocalized, much more so than for previously investigated monosaccharides,, and that marker bands could not be identified for the glycosidic linkages within these three disaccharides. This is in contrast with a study performed on agarose polysaccharides, where a similar combined computational and experimental ROA approach revealed a systematic sensitivity towards higher order structure. Previous studies of other disaccharides by ROA spectroscopy also seem to show clear glycosidic signatures as inferred in the discussion and that mannose therefore may be a special case.…”

“…The lack of informative marker bands in the mannobioses is intriguing, as this indicates a lack of spectral sensitivity in ROA towards conformational differences in carbohydrates. This is in contrast to the main body of previous empirical and computational carbohydrate ROA, where many spectral trends have been identified, indicating sensitivity to linkage type and even higher order structure ,,,,,. Thus, the mannobioses appear to be a special case.…”

Helical polysaccharides

“…Raman optical activity (ROA) allows for direct observation of highly hierarchical structures by monitoring the difference in Stokes scattering intensity of right and left circularly polarized light, thus introducing sensitivity for asymmetry and chirality. This technique has been used to determine the secondary structure of native and carboxylated agarose gels . Recently, ROA has been applied to dimannosides with different glycosidic linkages …”

Tracking Conformational Changes in Phosvitin throughout a Crowding‐Agent‐Based Titration

“…In the past, CID has been used as a method to determine the similarity between calculated and experimentally measured ROA spectra . However, in this study it is used as a method to validate the claims about the amounts of structural elements present in the described samples, because deviating CID intensities might indicate the presence, in the spectra, of artifacts originating in the subtraction method used during these experiments.…”