Design of polygalacturonate hydrogels using iron(II) as cross-linkers: A promising route to protect bioavailable iron against oxidation.
Carbohydr Polym
; 188: 276-283, 2018 May 15.
Article
em En
| MEDLINE
| ID: mdl-29525167
ABSTRACT
We designed stable and highly reproducible hydrogels by external unidirectional diffusion of Fe2+ ions into aqueous solutions of polygalacturonate (polyGal) chains. The Fe2+ ions act as cross-linkers between the Gal units in such a way that both the molar ratio R ([Fe2+]/[Gal units]â¯=â¯0.25) and the mesh size of the polyGal network at the local scale (ξâ¯=â¯75⯱â¯5â¯Å) have constant values within the whole gel, as respectively determined by titration and Small Angle Neutron Scattering. From macroscopic point of view, there is a progressive decrease of polyGal concentration from the part of the gel formed in the early stages of the gelation process, which is homogeneous, transparent and whose Young modulus has a high value of â¼105â¯Pa, up to the part of the gel formed in the late stages, which is heterogeneous, highly turbid and has a much lower Young modulus of â¼103â¯Pa. Since the local organization of the polyGal chains remains identical all along the hydrogels, this macroscopic concentration gradient originates from the formation of heterogeneities at a mesoscopic length scale during the gelation process. In addition, X-ray Absorption Spectroscopy measurements remarkably reveal that Fe2+ ions keep their +II oxidation state in the whole gels once they have cross-linked the Gal units. These polyGal hydrogels thus protect iron against oxidation and could be used for iron fortification.
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Compostos Ferrosos
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Ferro
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En
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2018
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Article