Synthesis of N‐(aminoalkyl) chitosan for microcapsules

Abstract

Chitosan was chemically modified by alkylation with N‐(2‐bromoethyl) phthalimide, N‐(3‐bromopropyl) phthalimide, and N‐(4‐bromobutyl) phthalimide. The resulting N‐(phthalidimidoalkyl) chitosans were treated with hydrazine to remove the phthalidimido group resulting in the final N‐(aminoalkyl) chitosan products. For comparison purposes, poly(vinyl alcohol) (PVA) was alkylated with N‐(3‐bromopropyl) phthalimide, then treated with hydrazine to give the N‐(3‐aminopropyl) PVA product. All alkylation products were characterized by solution 1H‐ and 13C‐NMR and by solid‐state CP‐MAS 13C‐NMR. The above synthetic polymer derivatives, as well as chitosan, polyallyl amine, and polyethylen‐imine, were used to form membrane coatings around calcium alginate beads in which blue dextran of molecular weight 7.08×104 or 26.6×104 was entrapped. These microcapsules were prepared by extrusion of a solution of blue dextran in sodium alginate into a solution containing calcium chloride and the membrane polymer. Membrane integrity and permeability were assessed by measuring the elution of the blue dextran from the capsules, spectrophotometrically. © 1993 John Wiley & Sons, Inc. Copyright © 1993 John Wiley & Sons, Inc.