Ion-mediated formation of alginate hydrogels incorporating a Vitis vinifera L. phytocomplex obtained from suspension cell cultures: A one-pot route to antioxidant patches

Alginate hydrogels are versatile soft materials for biomedical and industrial applications, yet conventional ionic gelation often yields heterogeneous networks and leads to loss of sensitive bioactives during processing. Here, we report a reproducible one-pot dual syringe mixing method that produces thin, defect-free alginate patches at very low cation concentrations without post-washing steps. By varying the crosslinking ion (Ca²⁺, Zn²⁺, Cu²⁺), we demonstrate systematic modulation of gel architecture and mechanics while maintaining a common carboxylate coordination mode. Multiscale characterization revealed ion-dependent differences in nanostructural organization, ion content, and macroscopic performance, with Cu²⁺ yielding stiff but brittle networks, Zn²⁺ producing highly elastic gels, and Ca²⁺ resulting in intermediate properties. Incorporation of a grape-derived phytocomplex obtained from suspension cell cultures served as a proof-of-concept, showing retention of the active molecules within the gels and sustained antioxidant activity. This approach establishes a generalizable platform for tuning the properties of alginate patches through ion selection, offering a versatile method to adapt them to biomedical, nutraceutical, or cosmetic applications.