Unravelling a Direct Role for Polysaccharide β-Strands in the Higher Order Structure of Physical Hydrogels.
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 toward carbohydrates-on native agarose and chemically modified agarose in the gel phase for the first time. By spectral global fitting, we isolated features that change as a function of backbone carboxylation (28, 40, 50, 60, 80, and 93 %) from other features that remain unchanged. We assigned these spectral features by comparison to ROA spectra calculated for different oligomer models. We found a 60:40 ratio of double- and single-stranded α-helix in the highly rigid hydrogel of native agarose, while the considerably softer hydrogels made from carboxylated agarose use a scaffold of unpaired β-strands.
Institute of Pharmaceutical Sciences, University of Freiburg, Albertstrasse 25, 79104, Freiburg, Germany.
Anja
A
Rüther
Science and Engineering Faculty, Queensland University of Technology, Brisbane, Australia.|Institute for Macromolecular Chemistry, University of Freiburg, Stefan-Meier-Str. 31, 79104, Freiburg, Germany.|BIOSS-Centre for Biological Signalling Studies, University of Freiburg, Germany.
Aurelien
0000-0002-3305-3980
A
Forget
BioTools, Inc., Jupiter, USA.
Anjan
A
Roy
BioTools, Inc., Jupiter, USA.
Carolina
C
Carballo
Institute for Macromolecular Chemistry, University of Freiburg, Stefan-Meier-Str. 31, 79104, Freiburg, Germany.
Florian
F
Mießmer
BioTools, Inc., Jupiter, USA.
Rina K
0000-0002-1981-3381
RK
Dukor
BioTools, Inc., Jupiter, USA.|Department of Chemistry, Syracuse University, Syracuse, USA.
Laurence A
0000-0002-3221-4332
LA
Nafie
Department of Chemistry, University of Antwerp, Belgium.
Christian
0000-0003-2613-9476
C
Johannessen
Institute for Macromolecular Chemistry, University of Freiburg, Stefan-Meier-Str. 31, 79104, Freiburg, Germany.|BIOSS-Centre for Biological Signalling Studies, University of Freiburg, Germany.
V Prasad
0000-0001-5125-9678
VP
Shastri
Institute of Pharmaceutical Sciences, University of Freiburg, Albertstrasse 25, 79104, Freiburg, Germany.
Steffen
0000-0003-1498-5552
S
Lüdeke
Raman optical activity; density functional calculations; hydrogels; polysaccharides; spectral fitting