Control of Transport Characteristic of Membrane by Multi-layering of Polyelectrolyte Complex Toward Microcapsule-shaped Bioartificial Pancreas

In order to develop a microcapsule-shaped bioartificial pancreas, it is important to control the transport characteristics of the semipermeable membrane. We attempt to control the transport characteristics of the membrane by changing the coating layer number of polyelectrolyte complex between glycol chitosan (GC, M. W.>8.2×104) and alginate (Alg) on the microcapsule. From measurement of diffusivities of bovine serum albumin (BSA, M. W.= 6.7×104) and γ-globulin (M. W.=1.6×105), these diffusion rates through the membrane drastically decrease with increasing layer number of GC-Alg. The microcapsule coated with four layers of polyelectrolyte complex successfully rejects γ-globulin with effective permeability of BSA. In addition, the diffusivity of glucose (M. W.=180) indicateds that the multi-layering of polyelectrolyte complex hardly affects the diffusivity of small substances such as nutrients and oxygen. These results indicate that the polyelectrolyte complex prepared by the multi-layering method is useful to control the transport characteristic of membranes and the four-layered GC-Alg polyelectrolyte complex microcapsule is promising for a microcapsule-shaped bioartificial pancreas Key words: polyelectrolyte complex, multilayer coating, immunoisolation, bioartificial pancreas, microcapsule.