2.1. Materials Chitosan (with a molecule weight of about 300 kDa and a90% degree of deacetylation) was purchased from Kiotek (Taipei,Taiwan). Pectin (about 9.4% methoxylation) and gum Arabic (fromthe acacia tree) were purchased from Sigma (St. Louis, MO, USA).Materials for the controlled-release experiments including insulinwere also purchased from Sigma.