Advances in fabricating spherical alginate hydrogels with controlled particle designs by ionotropic gelation as encapsulation systems

Alginate is a biopolymer that has exceptional gelling properties, which allow easy gel formation under safe and mild conditions. Consequently, it is often used to encapsulate a variety of cargos, such as cells, enzymes, and lipids, and is typically employed as a model to study hydrogel-based encapsulation systems. Since the first use of alginate in the encapsulation field in the 1970s, many methods have been developed to produce alginate hydrogel particles of different sizes, structures, and morphologies. This review provides an overview of the current progress in the fabrication of alginate hydrogels with various particle designs, including a discussion of dispersion techniques to pre-template alginate particles, gelation mechanisms, considerations in selecting suitable fabrication methods, and future directions.