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Research Article

pH-dependent release property of alginate beads containing calcium carbonate particles

, , , , , , & show all
Pages 787-796 | Received 22 May 2007, Accepted 31 Aug 2007, Published online: 08 Oct 2008
 

Abstract

Alginate bead containing calcium carbonate particle were prepared by dropping the suspension of alginate/calcium carbonate (4/1, w/w) into aqueous solution of CaCl2 (0.1 M). The pH-dependent release property of the bead was observed for 12 h using blue dextran as a model drug. The release increased up to 4 h in a saturation manner. When no calcium carbonate was contained, the release exhibited no marked variation with pH and the values were 27–39%. On the other hand, in case calcium carbonate was included in the matrix of alginate beads, intensive release(40–50%) was achieved in acidic and neutral conditions and the degrees of release were suppressed in alkali conditions and the values were ∼20%. The pH-sensitive release property is possibly because the particles of calcium carbonate embedded in the matrix of beads were leached out in acidic and neutral conditions, leaving cavities in the matrix. The cavities are likely to be main pathways for the release of blue dextran.

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