Trivalent iron induced gelation in Artemisia sphaerocephala Krasch. polysaccharide

Artemisia sphaerocephala Krasch. polysaccharide (ASKP) has attracted growing attention in the field of food and medical engineering due to its biological activity and colloidal property. In this study, the binding between ASKP and ferric ions was found and the binding mechanism was explored. The results showed that ASKP could form a hydrogel with three-dimensional network structure in the presence of ferric ions. Ferric ions could specifically bind with the carboxyl and hydroxyl groups of the high molecular weight fraction of 60P with the binding stoichiometry of [M³⁺]/[repeating unit] = 2.5. The possible mechanism of the formation of ASKP-Fe³⁺ complex was proposed as two binding modes of monodentate and bridging binding. ASKP-Fe³⁺ complex exhibited higher thermal stability than ASKP revealed with DSC thermograms. The study indicated that ASKP would be a novel gelation biopolymer and the ASKP-Fe³⁺ complex hydrogel could be exploited as a new iron fortifier.