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Method of containing core material in microcapsules

  • US 5,795,570 A
  • Filed: 04/07/1995
  • Issued: 08/18/1998
  • Est. Priority Date: 04/07/1995
  • Status: Expired due to Fees
First Claim
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1. A method of containing a core material within microcapsules having a semipermeable wall to prevent the core material from incorporation into the wall of the microcapsules which comprises:

  • (a) suspending the core material in a solution containing between about 0.2% and about 0.5% of a polysaccharide gum containing acid groups capable of forming a gel to permit the polysaccharide gum to attach to the core material, wherein the solution of polysaccharide gum is physiologically compatible with the core material;

    (b) removing the core material from the solution of polysaccharide gum in step (a) and washing the core material in a solution not containing the polysaccharide gum to remove from the core material all but a thin layer of polysaccharide gum attached to the core material;

    (c) treating the washed core material having the attached thin layer of polysaccharide gum from step (b) under conditions to cause the polysaccharide gum attached to the core material to gel to form a pretreated core material;

    (d) suspending the pretreated core material from step (c) in a solution containing a polysaccharide gum containing acid groups capable of forming a gel, wherein the solution of polysaccharide gum is physiologically compatible with the core material;

    (e) forming the suspension from step (d) into droplets of a size sufficient to encapsulate the core material;

    (f) treating the droplets from step (e) under conditions to cause the polysaccharide gum to gel to form temporary shape-retaining capsules; and

    (g) treating the temporary shape-retaining capsules from step (f) under conditions with a polymeric material containing groups that react with and crosslink acid groups of the temporary shape-retaining capsules to cause the formation of a permanent semipermeable membrane around the capsules to form said microcapsules.

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