Abstract: It is essential to investigate the diffusion characteristics of alginate-polylysine-alginate(APA) microcapsule system for its broad applications. An advanced mathematical model for protein diffusion in APAmicrocapsules is established, which presents the resistance coefficient of microcapsule membrane and distribution coefficient in microcapsule matrix. These two parameters as the important basis of optimizing preparation and directing application of microcapsule are determined by the measurement of the protein concentration in the extracapsular solution. With assistance of mathmatical model, membrane diffusion characteristics affected by reaction time in membrane forming are analyzed: (1) microcapsule shows greater resistance constant and distribution constant to the diffusion of protein with greater molecular weight, (2) prologation reaction time results in increase in resistance constant and distribut constant of microcapsule.

Key words: APA microcapsule, Mathematical model, Resistance coefficient, Distribution coefficient