PARTICLES WITH HIGH UNIFORM LOADING OF NANOPARTICLES AND METHODS OF PREPARATION THEREOF
First Claim
1. A method for enhancing uniformity of dispersion and increasing loading of nanoparticles in a polymeric microparticle comprising(a) forming a homogeneous dispersion of nanoparticles in a polymer solution optionally containing surfactant,(b) sonicating or exposing the polymer solution to shear forces effective to crease a stabilized dispersion of the polymer solution wherein the nanoparticles remain suspended for at least thirty minutes, preferably at least two hours, and(c) forming microcapsules by a process selected from the group consisting of spray drying, solvent evaporation, interfacial polymerization, hot melt encapsulation, phase separation encapsulation, spontaneous emulsion, solvent evaporation microencapsulation, solvent removal microencapsulation, coacervation, low temperature microsphere formation, and phase inversion nanoencapsulation.
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Accused Products
Abstract
Methods to produce polymeric microparticles containing nanoparticles such, as pigments, dyes and other chromophores for cosmetic use, plastic surgery therapeutic use, and tattoos have been developed. The microparticles contain within the polymer a very uniform dispersion of dye particles. The methods by which the particles are made ensure a homogeneous mixture and high loading. The microparticles are made using air, one of a number of known methods such as phase inversion, solvent evaporation, and melt processing. The improvement is in the use of a method that makes, a stable dispersion of the nanoparticles in the liquid polymer before formation of the microparticles. This is achieved through selection of appropriate solvent, optionally including surfactant, and then subjecting the dispersion to mechanical processing that stabilizes the dispersion within the polymer solvent, so that the nanoparticles remain suspended for at least thirty minutes, in some cases two hours to 48 hours, sometimes up to three months. The mechanical processing can be sonication and/or production of shear forces, for examples, resulting from use of an open blade or rotor stator mixer or milling with a concentric shaft, at a speed such as between 5000 and 25,000 RPM.
31 Citations
28 Claims
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1. A method for enhancing uniformity of dispersion and increasing loading of nanoparticles in a polymeric microparticle comprising
(a) forming a homogeneous dispersion of nanoparticles in a polymer solution optionally containing surfactant, (b) sonicating or exposing the polymer solution to shear forces effective to crease a stabilized dispersion of the polymer solution wherein the nanoparticles remain suspended for at least thirty minutes, preferably at least two hours, and (c) forming microcapsules by a process selected from the group consisting of spray drying, solvent evaporation, interfacial polymerization, hot melt encapsulation, phase separation encapsulation, spontaneous emulsion, solvent evaporation microencapsulation, solvent removal microencapsulation, coacervation, low temperature microsphere formation, and phase inversion nanoencapsulation.
Specification