Fabrication of high strength cold-set sodium alginate/whey protein nanofiber double network hydrogels and their interaction with curcumin

Enhancing the bio-based hydrogels strength is fundamental to extend their engineering applications. In this study, high strength cold-set sodium alginate/whey protein nanofiber (SA/WPN) double network hydrogels were prepared and their interaction with curcumin (Cur) was studied. Our results indicated that the rheological and textural properties of SA/WPN double network hydrogels were enhanced with increasing WPN by forming SA-COO--Ca2+--OOC-WPN bridge through electrostatic interactions. The storage modulus (768.2 Pa), hardness (273.3 g), adhesiveness (318.7 g·sec) and cohesiveness (0.464) of SA/WPN50 (WPN concentration of 50 mg/mL) double network hydrogels were 3.75, 2.26, 3.76 and 2.19 times higher than those of SA hydrogels, respectively. Cur was combined with SA/WPN hydrogels through hydrogen bonding, van der Waals forces and hydrophobic interactions with an encapsulation efficiency of 91.6 ± 0.8 %, and the crystalline state was changed after binding. In conclusion, SA/WPN double network hydrogels can be enhanced by the addition of WPN and have potential as carriers for hydrophobic bioactive substances.