Gelatin-Based Zinc-Loaded Hydrogels Constructed with the Assistance of Sodium Alginate and Zinc Sulfate Solution Soaking Method

Constructing a zinc delivery system is crucial for scientific zinc supplementation. In this study, gelatin-based zinc-loaded hydrogels were constructed with the assistance of sodium alginate and a ZnSO₄ solution soaking method. The zinc loading capacity, texture properties, rheological properties, microstructure, and pH sensitivity of hydrogels under different ratios of gelatin to sodium alginate were investigated. Results showed that the loading of zinc by hydrogel was successfully achieved through a ZnSO₄ solution soaking method, and increasing the ZnSO₄ concentration was conducive to zinc loading and hydrogel structure strengthening. Adding sodium alginate further enhanced the zinc loading capacity of hydrogel. When the concentration of ZnSO₄ was 25 wt%, the zinc loading of hydrogel containing only gelatin and hydrogel with a 7:3 ratio of gelatin to sodium alginate was 29 mg/g and 52 mg/g, respectively. In addition, sodium alginate also endowed the hydrogel with a certain pH sensitivity. When the ratio of gelatin to sodium alginate was 7:3, the hydrogel showed obvious pH response behavior. Spectroscopy results revealed that zinc sulfate strengthened the hydrogel structure by inducing hydrophobic interactions and the formation of hydrogen bonds, while Zn²⁺ was bound to oxygen atoms through coordination bonds in hydrogel. These results could provide new ideas for the construction of zinc-loaded hydrogels.