Electrohydrodynamic preparation of polymeric drug-carrier particles: mapping of the process.

Submicrometre size spheres prepared from biocompatible polymers are becoming increasingly popular in drug and gene delivery. This paper describes the preparation of polymeric spheres with a mean diameter of 0.4 μm with a polydispersivity index of 8%, using coaxial electrohydrodynamic atomization (CEHDA) microbubbling. An 18 wt.% solution of polymethylsilsesquioxane, a hydrophobic biocompatible polymer, was subjected to CEHDA microbubbling by passing air through the inner needle and polymer solution through the outer needle of a twin needle co-axial device, under the influence of an electric field. A parametric plot of the flow rate of air and the flow rate of polymer solution was constructed and used for systematic process control to reduce the diameter of the microspheres from micrometre size to submicrometre size. CEHDA is an excellent method for obtaining polymer microspheres. By studying the process in detail and mapping it, we can now demonstrate it can also be used to prepare submicrometre sized particles with the ability to control size and polydispersivity.