Retention of insulin in alginate gel beads

Gels prepared from synthetic or natural polymers have been used to entrap cells and proteins.'-7 Diffusion of small molecules both into and out of the gel beads is usually dependent on the pore size of the gel. For example, Tanaka and co-workers3 studied the diffusion of a number of proteins and smaller molecules into and out of beads of calcium alginate gel and showed that for proteins larger than albumin, diffusion was considerably restricted. This gave an indication of the limiting value of size of pores in the particular gel which they used. Some evidence3 was presented that the pore size of the calcium alginate gel was dependent on the concentration of alginate used in its preparation.