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Study on the Preparation and Performance of Multifunctional Pla Microcapsules

Author: LuRong
Tutor: SunKang
School: Shanghai Jiaotong University
Course: Materials Science
Keywords: Polylactic acid Microcystis Fe3O4 Magnetic nanoparticles Complex Double emulsion Interface coprecipitation Sound attenuation Resonance frequency
CLC: R944
Type: PhD thesis
Year: 2010
Downloads: 278
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Abstract

In recent years, polymer microcapsules attracting much attention because of its broad application prospects in the field of drug delivery, artificial red blood cells, biomedical ultrasound contrast. After embedding inorganic nanoparticles Polymer microcapsules, in addition to having a micro carrier function, but also both the inorganic nano-particles, acoustic, magnetic, optical, thermal and other excellent properties. This article will exceed paramagnetic Fe ₃ O ₄ nanoparticles composite shell and the cavity of polylactic acid microcapsules not only make the microcapsules with magnetic resonance angiography the potential, but also improve the microcapsules ultrasound responsiveness to obtain a multi-purpose carrier for both magnetic resonance imaging and ultrasound imaging. First, by adjusting the process parameters of the double emulsion method to study the microcapsules and the variation of the internal structure. In view of the importance of the hollow structure of the carrier function, we proposed two concepts of \The study shows that, for the first time the emulsion water-oil ratio is the key factors affecting the microcapsules hollowness, too high or too low is not conducive to obtain the hollow microcapsules; addition, a suitable concentration of the external aqueous phase emulsifier altitude heart rate guarantee; micro The size of the capsule diameter and the inner water phase droplets close, lower second emulsification energy can be obtained microcapsules of large particle diameter of the multi-lumen structure. In depth understanding of the characteristics and particle size of the microcapsule structure of the impact mechanism, we have successfully prepared an average particle diameter of 12μm, 10μm, 8μm, 6μm, a single cavity altitude heart rate of 5 μm and 4μm polylactic acid microcapsules. On the basis of the above-mentioned work, the thermal decomposition of the obtained oil-soluble Fe ₃ O ₄ nano-particles and the polylactic acid-macromolecular complexes by the double emulsion - solvent evaporation method. Fe ₃ O ₄ the magnetic shell of the nano-particles in the shell in the polylactic acid microcapsules, magnetic content is 13 wt.% when the corresponding saturation magnetization intensity of 4.6 emu / g. Through the control of the shell structure, the first variation of the shell structure of the composite microcapsules: With the extension of the second emulsion speed increase or time, the microcapsules in order from the cellular structure into a multi-cavity, concentric, eccentric, bowls shape and crater-shaped, and finally into a solid structure, and is accompanied by the gradual decrease of the average particle diameter. This article also invented a novel interface of precipitate joint the breasts method, Fe ₃ O ₄ nanoparticles of the compound in the cavity of the polylactic acid microcapsules. The law will be water in the aqueous ferrous salt solution as the inner phase, the di-n-propylamine was dissolved in the polylactic acid in methylene chloride solution as the oil phase, to generate water-soluble Fe ₃ O ₄ nano The coprecipitation reaction is carried out in the double emulsion oil-water interface in the interface of the particles. Fe ₃ O ₄ nanoparticles in the oil-water interface generation, because of its hydrophilic into inner water phase, within the aqueous phase as Microcystis cavity before body, the aqueous phase within the freeze drying sublimation the of Fe ₃ O ₄ nano-particles remain in the cavity of the microcapsule, thereby succeeded in obtaining the magnetic cavity polylactic acid microcapsules . The method to achieve the synthesis of magnetic nanoparticles and magnetic polymer microcapsules prepared simultaneously, greatly simplifies the process of preparation of composite microcapsules. The study found that ferric salt feeding amount and ultrasonic oscillation time are key factors affect the the composite microcapsules magnetic content and magnetic improve molysite feeding amount and extend the time of ultrasonic vibration to get the magnetic content of 38 wt.%, Corresponding saturation magnetization of 22 emu / g magnetic cavity polylactic acid microcapsules. Synthesis mechanism of that the ultrasonic oscillations promote coprecipitation reactions carried interface, so the resulting Fe ₃ O ₄ nanoparticles saturation magnetization of 78 emu / g, and eventually improve the magnetic properties of the composite microcapsules. Finally, sound attenuation by covering medical ultrasound frequency (0-10 MHz) spectra of different particle sizes, the acoustic behavior of different shell structure, composite structure and its magnetic content polylactic acid microcapsules. Found: With the increase in average particle diameter, the microcapsule resonant frequency was increased, and the entire frequency range of the sound attenuation change significantly; concentric microcapsules resonance frequency and the entire frequency range of the sound attenuation are higher than the crater and chamber microcapsule, the multi-lumen microcapsules porous loose their shell structure, the lowest resonance frequency; With the magnetic content in the shell is increased from 0 wt.% to 13 wt.%, magnetic shell poly lactic acid microcapsules resonance frequency sound attenuation gradually increased, and the resonance frequency when the the cavity magnetic content increased from 12 wt.% to 38 wt.%, the microcapsule was almost unchanged, and the entire frequency range of the acoustic attenuation has declined; magnetic content, and the cavity in the shell different effects brought about by the changes in the magnetic content, reflecting the impact of the composite structure of the the microcapsules acoustic performance. CEUS in vitro showed that the magnetic content 13 wt of the magnetic shell the video strength of polylactic acid microcapsules significantly higher than polylactic acid microcapsules, they sound attenuation measurements anastomosis.

Study on the Preparation and Performance of Multifunctional Pla Microcapsules

Abstract

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