Effect of alginate composition and gelling cation on microbead swelling

The purpose of this study was to determine the roles of alginate composition and gelling cations on bead swelling, which affects its durability.Using a 2-channel droplet generator, microspheres were generated with 1.5% solutions of low viscosity high-mannuronic acid (LVM), medium viscosity high-mannuronic acid (MVM), low viscosity high-guluronic acid (LVG) and medium viscosity high-guluronic acid (MVG) alginate. They were gelled by cross-linking with 1.1% solution of either BaCl2 or CaCl2. The diameters of the microbeads were measured and recorded on day 0. The microbeads were subsequently washed and incubated in saline at 37 degrees C for 2 weeks with size assessment every 2 days. The data were normalized by calculation of the percentage change from control (day 0) for all groups of microbeads.Diameters of all beads were between 550-700 microns on day 0. Viscosity had no effect on swelling of Ba++- and Ca++-alginate microbeads. Ca++-alginate microbeads were more prone to swelling than the corresponding Ba++-alginate beads. High G-Ba++ beads had only a modest increase in size over time, in contrast to the high M-Ba++.Alginate composition and the gelling cation have significant effects on bead swelling.