In a glass tube (15 mm in diameter and 65 mm long) dissolve 0.3 grams of polymer in 2 ml of methylene chloride.
While gently vortexing the dissolved polymer solution, add 100 µl of the encapsulant solution drop-wise.
Sonicate the solution on ice for 10 seconds.
Place the tube on ice. Add 4 ml of a 1.0% polyvinyl alcohol solution slowly (maintain the phase separation).
Repeat sonication on ice for 10 seconds.
Set up a 400 ml beaker with a stirring rod on a magnetic stir plate. Add 100 ml of 0.3 % polyvinyl alcohol.
Pour the emulsion into the center of the stirred solution. Stir for 3 hours.
Centrifuge the emulsion and wash the microparticles three times (4000 RPM, 10 minutes, 4oC).
After the final rinse re-suspend the microparticles in 5-10 ml of distilled water. Freeze the mixture in liquid nitrogen.
Lyophilize the microparticles until they are dry.