Property and biocompatibility of alginate-based gel beads and microcapsules

Calcium exists in alginate gel in both free and binding forms. Removal of Ca ion resulted in an irreversible expansion of the gel film. The transfer rate of glucose decreased by the coating of poly-L-lysine onto the alginate bead, but increased significantly after the removal of excessive Ca⁺² and alginate from the poly- L-lysine coated gel bead. ESCA results indicated that the microcapsular membrane consisted of a network structure formed by entangling of alginate and ploy-L-lysine. Alginate had very poor biocompatibility with tissue fibrosis and extensive coverage of dead cells on its surface after implantation. On the other hand, the capsular membrane of alginate/poly-L- lysine had only few cells deposited on the surface, but the capsules were often attached to the mesentery tissue.