Soybean protein isolate/dialdehyde sodium alginate hydrogels based on dynamic imine bond cross-linking: Synthesis and properties

A soybean protein isolate (SPI)-based hydrogel with controllable properties was prepared under mild conditions using a simple mixing method with dialdehyde sodium alginate (DSA) as an eco-friendly macromolecular crosslinker. DSA was successfully synthesized via periodate oxidation. Analysis of the structure of the SPI/DSA hydrogel indicated that a 3D network was formed between SPI and DSA through dynamic imine and hydrogen bonds. The analysis of the physicochemical properties of the hydrogels showed that the micropore size, mechanical properties, and the swelling and release behavior of the hydrogels could be effectively regulated by changing the DSA content. When 3.0 wt% DSA was added, the hydrogel exhibited a dense and homogeneous network structure with optimal gel properties, which enabled the controlled release of curcumin. This effective structure is mainly attributed to the synergistic effect of short- and long-range chemical and physical crosslinking. Overall, the SPI/DSA hydrogels are effective carriers for the controlled release of bioactive compounds.