title: Effect of Ca2+, Ba2+, and Sr2+ on alginate microbeads.
abstract: Microcapsules of alginate cross-linked with divalent ions are the most common system for cell immobilization. In this study, we wanted to characterize the effect of different alginates and cross-linking ions on important microcapsule properties. The dimensional stability and gel strength increased for high-G alginate gels when exchanging the traditional Ca2+ ions with Ba2+. The use of Ba2+ decreased the size of alginate beads and reduced the permeability to immunoglobulin G. Strontium gave gels with characteristics lying between calcium and barium. Interestingly, high-M alginate showed an opposite behavior in combination with barium and strontium as these beads were larger than beads of calcium-alginate and tended to swell more, also resulting in increased permeability. Binding studies revealed that different block structures in the alginate bind the ions to a different extent. More specifically, Ca2+ was found to bind to G- and MG-blocks, Ba2+ to G- and M-blocks, and Sr2+ to G-blocks solely.
authors: Department of Biotechnology, Norwegian University of Science and Technology, Sem Saelands vei 6/8, 7491 Trondheim, Norway. yrrm@ntnu.no
authors: Yrr A
authors: YA
authors: Mørch
authors: Ivan
authors: I
authors: Donati
authors: Berit L
authors: BL
authors: Strand
authors: Gudmund
authors: G
authors: Skjåk-Braek