Article,
Alginate polycation microcapsules .2. Some functional properties
Biomaterials, 17 (11): 1069 -- 1079 (June 1996)
Abstract
The main cause of alginate polycation capsule breakage under physiological
conditions is probably the osmotic swelling of the alginate core
owing to the Donnan equilibrium set up by the negative charges of
the carboxyl groups not involved in cooperative binding of counterions
in the junction zones of the network. In the present paper we show
how capsules can be stabilized extensively by reducing their swelling
capacity in various ways. Alginate polycation capsules with good
chemical and mechanical stability have been made by controlling their
swelling behaviour through selection of capsule material according
to chemical structure and molecular weight, as well as by controlling
the kinetics of the capsule formation. Stable capsules have been
made either by increasing the strength of the polyanion-polycation
membrane, or by keeping a low-swelling gel network in the core. The
latter capsules are made from an alginate rich in guluronic acid
both in the core and in an outer coating, and with anisotropic distribution
of the polymer material in the core where the concentration at the
surface is higher than that in the centre of the capsule. Some functional
properties of these capsules, such as porosity, have also been studied.
(C) 1996 Elsevier Science Limited
Tags
- ;
- ;;
- acid
- alginate;
- beads;
- cytokine
- functional
- gel
- immobilization
- insulin
- insulin;
- islets;
- material;
- microcapsules;
- microencapsulation;
- production;
- properties;
- release;
- swelling;
- transplantation
- [isi:]
