FACTORS AFFECTING THE PARTICLE SIZE AND IN VITRO RELEASE OF BOVINE SERUM ALBUMIN FROM POLYETHYLENE GLYCOL MICROPARTICLES

摘要

Bovine serum albumin was encapsulated in polyethylene glycol (20,000 MW) microparticles using a modified double emulsion method. Particle size, release rate, and encapsulation efficiency were measured for microparticles when varying multiple process factors such as sonication time, sonication intensity and drug loading. For all procedures, ninety percent of the particles were less than 2 jam in diameter. Particle size was reduced by extending the preparation's exposure to sonication over a range of 30 to 120 s, increasing the sonication intensity from 5 to 20 W or varying the polymer to protein ratios from 10 to 100:1. Perhaps of more interest, the particle size distribution was substantially narrowed at the upper end of each parameter compared to the lower end. Substantial differences were observed at the upper and lower end of each varied process parameter. Upon examination of protein release from microparticles over 120 minutes, the burst effect was minimized at the upper end of each parameter. Encapsulation efficiency and the time to release 50% of the entrapped protein were greatest at the lower end. In conclusion, production process parameters significantly affect protein release rates while their effect on particle size is less significant. These particles could be utilized when delayed, but not necessarily extended, release period is desired.