Permeability of alginate/sol–gel synthesized aminopropyl-silicate/alginate membrane templated by calcium-alginate gel

An alginate/aminopropyl-silicate/alginate membrane was prepared on calcium-alginate gel beads via electrostatic interaction and sol–gel processes. The effects of the chemical composition and the molecular weight (MW) of the core alginate on the permeability of the alginate/aminopropyl-silicate/alginate membrane were investigated for five different types of alginates. Our data shows that an immunoisolatable MW cut-off point was achieved for the membranes formed on the alginates, MW=7.0×104 with molar ratio of M/G (mannuronic acid to guluronic acid), M/G=1.30, MW=1.1×105 with M/G=1.30, and MW=7.0×104 with M/G=0.65. For these three membranes, the membrane templated by the alginate of MW=1.1×105 had a higher MW cut-off point than that templated by the alginate of MW=7.0×104. In addition, the MW cut-off point increased with an increase in the content of guluronic acid. The membranes formed on the alginates of MW=2.0×104 with M/G=1.30, and MW=7.0×104 with M/G=2.25 did not have an immunoisolatable MW cut-off point.