Interactions between gelatin and sodium alginate: UV and FTIR studies

The interaction between macromolecular chains of gelatin and anionic polysaccharide sodium alginate during the formation of polyelectrolyte complexes was examined using UV and FTIR spectroscopy. It has been shown that in an aqueous phase, where the pH is slightly higher than the pI of gelatin, complexes are formed through hydrogen bonds as well as electrostatic interactions between two biopolymers. The complex formation is accompanied by a change in the secondary structure of gelatin. At a low weight (w/w) ratio of polysaccharide to gelatin (up to 0.2) a decrease in the share of collagen-like helices and an increase in the share of the random coil conformation of gelatin chains were reported. SEM was used to identify a fundamental distinction between the morphologies of the gelatin hydrogel and the mixed alginate–gelatin hydrogel with a low mass ratio of biopolymers. Spherical formations were found in the structure of the latter that were interpreted as aggregations of complexes.