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Lipid-coated condensed-phase microparticle composition

  • US 5,753,261 A
  • Filed: 05/17/1995
  • Issued: 05/19/1998
  • Est. Priority Date: 02/12/1993
  • Status: Expired due to Fees
First Claim
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1. A composition for release of a compound upon exposure to a target stimulus selected from the group consisting of pH, temperature, radiation, a ligand and an ion-channel activator, comprisingencapsulated microparticles having an average size between 0.05 and 5 microns, each encapsulated microparticle being composed of(i) an external lipid bilayer membrane effective to allow influx of external ions into the particle interior when exposed to said target stimulus,(ii) encapsulated within the lipid membrane, a condensed-phase microparticle which is composed of a matrix of crosslinked polyionic polymer filaments, and which is capable of decondensing to an expanded state when multivalent counterions also present within the matrix are replaced by monovalent counterions, and(iii) the compound to be released entrapped in the microparticle matrix, with said matrix in its condensed phase,whereby localized perturbation of the lipid membrane, and influx of monovalent counterions into the microparticle matrix, in response to said target stimulus, causes swelling and compound release from said microparticles.

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