This review compiles information regarding the use of alginate, and in particular alginate hydrogels, in culturing cells in 3D. Knowledge of alginate chemical structure and functionality are shown to be important parameters in design of alginate-based matrices for cell culture. Gel elasticity as well as hydrogel stability can be impacted by the type of alginate used, its concentration, the choice of gelation technique (ionic or covalent), and divalent cation chosen as the gel inducing ion. The use of peptide-coupled alginate can control cell–matrix interactions. Gelation of alginate with concomitant immobilization of cells can take various forms. Droplets or beads have been utilized since the 1980s for immobilizing cells. Newer matrices such as macroporous scaffolds are now entering the 3D cell culture product market. Finally, delayed gelling, injectable, alginate systems show utility in the translation of in vitro cell culture to in vivo tissue engineering applications. Alginate has a history and a future in 3D cell culture. Historically, cells were encapsulated in alginate droplets cross-linked with calcium for the development of artificial organs. Now, several commercial products based on alginate are being used as 3D cell culture systems that also demonstrate the possibility of replacing or regenerating tissue.

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Alginates in the format of scaffolds provide important functions as materials for cell encapsulation, drug delivery, tissue engineering and wound healing among others. The method for preparation of alginate-based foams presented here is based on homogeneous, ionotropic gelation of aerated alginate solutions, followed by air drying. The method allows higher flexibility and better control of the pore structure, hydration properties and mechanical integrity compared to foams prepared by other techniques. The main variables for tailoring hydrogel properties include operational parameters such as degree of aeration and mixing times and concentration of alginate, as well as macromolecular properties such as the type of alginate (chemical composition and molecular weight distribution). Exposure of foams to γ-irradiation resulted in a dose-dependent (0-30 kGy) reduction in molecular weight of the alginate and a corresponding reduction in tensile strength of the foams.