Biodegradable polymers are a group of promising materials for various applications such as packaging, cosmetics, food, pharmaceutical and biomedical engineering. Due to their good biocompatibility and biodegradability, biodegradable polymers are often used to fabricate micro-/nano-particles as vehicles of drugs, growth factor, cosmetics ingredients, antimicrobials and so on. Among these, poly(lactic acid) (PLA) is one of the most commonly used biodegradable polymer and thus is used here to study the fabrication of various kinds of PLA composite micro-/nano-particles. In this study, various types PLA composite micro-/nano-particles were prepared based on the one-step double (W/O/W) emulsion method developed in our group. Firstly, biodegradable magnetic particles with different sizes were prepared via the adaptable emulsion setup for the potential applications in magnetic resonance imaging (MRI) and magnetic drug delivery. Via the simple adjustment of emulsification temperature to high temperature or room temperature, a transformation of PLA-iron oxide nanoparticles (IONPs) composite particles from hollow microparticles to solid nanospheres can be achieved. This study presents a fast and easily adaptable process to encapsulate either hydrophobic or hydrophilic IONPs into the hydrophobic polymeric particles, with different shapes and sizes, by simply adjusting the emulsification temperature at the specific mixing condition in the one-step W/O/W emulsion process. Secondly, a new system of heterogeneous PLA-polystyrene (PS) bioblend thin hollow microparticles with uniform hemispherical multicompartments and the subsequently formed PLA porous (Cagelike) microparticles were firstly developed via the one-step W/O/W emulsion combined with solvent-induced phase separation (SIPS) method. The driven forces for this unique multicompartmental structure are the dramatic change of the solubility of PS in ethyl acetate and the rapid solvent removal rate from the diffusion process. The overall microparticle size decreased with increasing amount of PS while the relative size of PS protrusion particle increased along with increasing PS. By replacing the solvent with a different solvent (toluene) or the PS with a different polymer (polycaprolactone, PCL), different anisotropic particles were obtained. Lastly, PLA/nanoclay (various types) composite microparticles were developed and the key factors of controlling particle morphology were studied by both experiments and design of experiment (DOE) factorial analysis. Surfactant concentration was identified as the most effective parameter, compared to other factors including nanoclay/PLA ratio, pH of the water phase, viscosity and emulsion duration. The TGA analysis showed a relatively high content (~43%) of hydrophilic nanoclay (MMT) in the final PLA/nanoclay composite particles. A model drug (diclofenac) was encapsulated to study the nanoclay-drug interaction because of the high cation exchange capacity of nanoclay. The result showed that negatively charged natural nanoclay is not ideal for anionic or non-ionic drugs.
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