HEMOGLOBIN ENCAPSULATION IN CHITOSAN CALCIUM ALGINATE BEADS/

A mild chitosan/calcium alginate encapsulation process, as applied to encapsulation of hemoglobin, was investigated. The first procedure con sisted of adding dropwise a hemoglobin-containing sodium alginate mixt ure in a chitosan solution, then hardening the interior of capsules th us formed, in the presence of CaCl2. In the second method, the droplet s were directly pulled off in a chitosan-CaCl2 mixture. Both procedure s led to beads containing a high concentration in entrapped hemoglobin as more than 90% of the initial concentration (150 g/L) were retained inside the beads provided that the chitosan concentration was great e nough. The molecular weight of chitosan ((M) over bar(nu) 245,000 or 3 90,000) and the pH of its solution (2, 4, or 5.4) had only a slight ef fect, the best retention being obtained with beads prepared at pH 5.4. The hemoglobin release during the bead storage in water was found to depend on the conditions of their formation and especially on the chit osan molecular weight. The best retention during storage in water was obtained with beads prepared with the high M(nu) chitosan solution at pH 2. Considering the total loss in hemoglobin during the bead formati on and after 1 month of storage in water, the best results were obtain ed by preparing the beads in an 8 g/L solution of a 390,000 chitosan a t pH 4 (less than 7% of loss with regard to the 150 mg/L initial conce ntration). (C) 1994 John Wiley & Sons, Inc.