Alginates are a broad family of linear (unbranched) polysaccharides derived from brown seaweeds and some bacteria. Despite having only two monomers, i.e. β-D-mannuronate (M) and its C5 epimer α-L-guluronate (G), their blockwise arrangement in oligomannuronate (.MMM.), oligoguluronate (.GGG.), and polyalternating (.MGMG.) blocks endows it with a rather complex interaction pattern with specific counterions and salts. Classic polyelectrolyte theories well apply to alginate as polyanion in the interaction with monovalent and non-gelling divalent cations. The use of divalent gelling ions, such as Ca2+, Ba2+ or Sr2+, provides thermostable homogeneous or heterogeneous hydrogels where the block composition affects both macroscopic and microscopic properties. The mechanism of alginate gelation is still explained in terms of the original egg-box model, although over the years some novel insights have been proposed. In this review we summarize several decades of research related to structure-functionships in alginates in the presence of non-gelling and gelling cations and present some novel applications in the field of self-assembling nanoparticles and use of radionuclides.

Alginate-metal cation interactions: Macromolecular approach

Donati I.;
2023-01-01

Abstract

Alginates are a broad family of linear (unbranched) polysaccharides derived from brown seaweeds and some bacteria. Despite having only two monomers, i.e. β-D-mannuronate (M) and its C5 epimer α-L-guluronate (G), their blockwise arrangement in oligomannuronate (.MMM.), oligoguluronate (.GGG.), and polyalternating (.MGMG.) blocks endows it with a rather complex interaction pattern with specific counterions and salts. Classic polyelectrolyte theories well apply to alginate as polyanion in the interaction with monovalent and non-gelling divalent cations. The use of divalent gelling ions, such as Ca2+, Ba2+ or Sr2+, provides thermostable homogeneous or heterogeneous hydrogels where the block composition affects both macroscopic and microscopic properties. The mechanism of alginate gelation is still explained in terms of the original egg-box model, although over the years some novel insights have been proposed. In this review we summarize several decades of research related to structure-functionships in alginates in the presence of non-gelling and gelling cations and present some novel applications in the field of self-assembling nanoparticles and use of radionuclides.
2023
Pubblicato
https://www.sciencedirect.com/science/article/pii/S0144861723007452
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/3056003
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