Method of preparing gas-filled polymer matrix microparticles useful for echographic imaging

Abstract

A method is provided to prepare gas-filled, porous microparticles having a polymer matrix interior which are useful as ultrasound echogenic contrast agents. An oil-in-water suspension is formed, both phases are frozen, then the aqueous and nonaqueous frozen phases are removed by sublimation. The resulting porous microparticles can receive a gas and be used as an ultrasound contrast agent.

1 . A microparticle comprising an outer shell enclosing an inner polymer matrix, wherein the outer shell comprises a biologically compatible amphiphilic material, the inner polymer matrix is characterized by a network of interstitial void space surrounded by a web-like polymer structure, and the outer shell is not covalently linked to the inner polymer matrix.