Alginate

Alginate can be either extracted from brown algae or biosynthesized by bacteria. Alginate is composed of linear copolymers containing blocks of (1,4)-linked beta- D-mannuronate (M) and alpha-L-guluronate (G) residues. The proportion of of G-block determines the gel's physical strength. The molecular weight of alginate varies from 32,000 to 400,000 g/mol depending on the source.

Figure 1: Structure of alginate.

Alginate is a hydrophilic and negatively charged saccharide that can be used to form hydrogels.

This natural polymer can be synthesized into hydrogels using: physical cross-linking mediated by divalent cations. The mild method of preparation makes it suitable for encapsulation of cells and for control release of proteins and peptides.