Disruption of Polymer and Composite Microcapsule Shells under High-Intensity Focused Ultrasound

Abstract

A process has been described for obtaining polymer (polyelectrolyte) microcapsules and polyelectrolyte/magnetite composite microcapsules, as well as silica-based hybrid capsules via silane-type precursor hydrolysis, which gives rise to the formation of silica nanoparticles in the structures of shells containing different numbers of polymer layers. The polymer and nanocomposite microcapsules have been formed by successive adsorption of oppositely charged polyelectrolytes and/or nanoparticles on the surface of microparticles of vaterite, which is a polymorphous modification of calcium carbonate. The obtained shells of microcapsules of all types have been studied by atomic force microscopy, confocal fluorescence microscopy, and scanning electron microscopy before and after sonication. The effect of high-intensity focused ultrasound on the obtained samples of microcapsules has been investigated and the sonication parameters that ensure efficient disruption of their shells in an aqueous medium have been determined. It has been found that composite microcapsules containing magnetite nanoparticles in their shells are most sensitive to sonication. The obtained composite microcapsules are promising for developing new systems for delivery of biologically active substances and multifunctional coatings.