| Summary: | 碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 107 === This study aims to develop biodegradable polycaprolactone (PCL) microspheres with uniform particle size by emulsification assisted with ultrasonic atomization (EUA) for mass production with low material loss. Through high frequency (~43 kHz) vibrating surface on an ultrasonic nozzle, a thin liquid film of PCL oil solution was broken and uinform PCL microdroplets (particle size ~ 20-55 μm) were sprayed out softly and directly. The influence on particle size of microdroplets by ultrasonic module parameters was analyzed, including concentration of PCL solution, vibrating amplitude of atomizer, feeding rate of PCL solution, and collection distance. A vertical circulation flow field of poly vinyl alcohol (PVA) solution was settled to collect the PCL microdroplets, and about 8~11 wt% of PVA solution with high stable dispersion property was used to effectively improve the yield rate of PCL microspheres (yield rate of PCL microspheres ~ 89.8-98.2 wt%). The final particle size of PCL microspheres was ~5-18 μm, which meant there were about 60-75% of particle size shrinkage from microdroplets to solid microspheres. Furthermore, EUA further demonstrated drug-loaded PCL microsphere fabrication with Doxorubicin (Dox). The drug-loaded efficiency (DLE) in EUA was ~ 42.2%, and encapsulation efficiency (EE) of Dox-loaded PCL microspheres (DLPM) was ~ 3.21% with particle size ~5-20 μm. The in vitro releasing indicated that DLPM had a well-sustained release efficacy for about two week at 37°C under phosphate buffer saline (PBS, pH=7.4) and PBS containing fetal bovine serum (FBS). The morphology of DLPM before and after releasing experiment wasn’t significantly changed, which was analyzed by scanning electron microscope (SEM). Therefore, the release within two weeks was judged as the continuous diffusion of the drug from the microspheres. In PBS containing Pseudomonas lipase (PS), the morphology of DLPM was loose after releasing experiment. Among these enzyme, PS has the property of degradation of PCL, making DLPM released ~70% of the drug in two weeks.
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