Mechanical properties of alginate hydrogels manufactured using external gelation

Alginate hydrogels are commonly used in biomedical applications such as scaffolds for tissue engineering, drug delivery, and as a medium for cell immobilisation. Multivalent cations are often employed to create physical crosslinks between carboxyl and hydroxyl moieties on neighbouring polysaccharide chains, creating hydrogels with a range of mechanical properties. This work describes the manufacture and characterisation of sodium alginate hydrogels using the divalent cations Mg2+, Ca2+ and Sr2+ to promote gelation via non-covalent crosslinks. Gelation time and Young's modulus are characterised as a function of cation and alginate concentrations. The implications of this work towards the use of environmental elasticity to control stem cell differentiation are discussed. (C) 2014 Elsevier Ltd. All rights reserved.