Authors
Leonardo Severini, Letizia Tavagnacco, Giovanni De Bellis, Greta Petrella, Giancarlo Masci, Stefano Casciardi, Simone Luciani, Simona Sennato, Ester Chiessi, Emanuela Zaccarelli, Claudia Mazzuca
Published in
Carbohydrate polymers. Volume 389. Pages 125606. Oct 01, 2026. Epub Jun 30, 2026.
Abstract
Gellan gum, a linear anionic exopolysaccharide, is widely employed as a gelling agent owing to its biocompatibility and tunable rheological properties. Its degree of acylation determines high acyl (HA-Gg) and low acyl (LA-Gg) forms, yielding hydrogels with different chemical-physical properties. Rheological measurements show a distinct gelation mechanism: LA-Gg forms rigid, ionically crosslinked networks (G' ∼25 kPa; critical strain ≈2%) exhibiting two-step yielding, whereas HA-Gg produces softer elastic gels lacking hierarchical organization (G' ∼1 kPa; LVR extends up to ∼500% strain). Despite their wide use, the molecular mechanism by which acyl substituents affect Gellan gum gelation is still lacking. Here a comparison between HA-Gg and LA-Gg, combining spectroscopy, rheology, and atomistic molecular dynamics (MD) simulations within a single framework is performed, providing a molecular-level interpretation of these differences. In dilute regime, circular dichroism measurements reveals distinct behavior for LA-Gg and HA-Gg, in coil and double-helix conformations, respectively. MD simulations explain the observed features, showing that acylation enhances intra-helix hydrogen bonding, stabilizing the double-helix structure, while hindering calcium-mediated inter-helix associations. Overall, acylation exerts a dual effect: it strengthens local structural units, but weakening supramolecular connectivity. This interplay governs macroscopic mechanical response, enabling rational design of Gellan gum hydrogels with tailored properties.
PMID:
42586636
Bibliographic data and abstract were imported from PubMed on 13 Aug 2026.
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