Preparation of biodegradable polymer microcarriers by ultrasonic emulsification

The polymer material PCL (polycaprolactone) has good biodegradability and good performance on drug coating. For the long-term delivery drugs, the biodegradable polymers reduced drug side effects and enhanced the drug efficacy. This study combined emulsification and ultrasonic nozzle to prepare biodegradable polymer microspheres. The ultrasonic emulsification compared to other general emulsification methods had advantage of being stable and fast. In the process, the oil phase solution PCL flew through the ultrasonic nozzle at flow rate 0.5-5 ml/min. Through the standing wave energy on the nozzle surface, the PCL solution was sprayed into droplets. Then, the droplets were dripped into the aqueous phase solution PVA (Polyvinyl alcohol) to cure as the PCL microspheres. After the emulsification process was completed, the solution was poured into water to make the solvent of the emulsion solution volatilized. Finally, the solution was rinsed with water and the PCL microspheres were filtered by the filter. As a result, the PCL microspheres were able to be observed through an optical microscopy (OM) and a scanning electron microscopy (SEM). In order to measure the rate of degradation, the PCL microspheres were used for the experiment. The PCL microspheres at 2.8×1.2×1.4 cm
³
volume were poured into an amano Lipase PS solution at a concentration of 0.005 mg/ml. Then, the solution was under a constant temperature (50 °C) and stable shaking situation, and the weight changes of the PCL microspheres were recorded per day. The result shows that the PCL microspheres particle size was 30-75 μm and the PCL microspheres at 2.8×1.2×1.4 cm
³
volume were degraded fully in 7 days.