Figure 1.

Schematic representation of alginate gelation. Alginate gelation is mediated by the replacement of sodium ions with divalent calcium ions, allowing three-dimensional cross-linking. Gelation can be obtained through (a) diffusion, where calcium ions diffuse from a solution containing a highly soluble calcium salt (e.g., CaCl₂) to the alginate gels; or (b) internal gelation, where a low soluble source of calcium (e.g., CaCO₃) is mixed with the alginate, along with a slow acidifier (e.g., GDL), with production of a gel that assumes the shape of the container where it forms. Gelation by diffusion is used for cell microbeads production, while internal gelation is proposed here for the production of alginate microdisks. Scale bars: (a) 500 μm; (b) 5 mm.