Hollow polylactic acid microcapsules fabricated by gas/oil/water and bubble template methods

Abstract

Hollow capsules are gas-filled spherical particles. Hollow biodegradable capsules with a diameter of a few microns are expected to be used as diagnostic ultrasound contrast agents and carriers of drug-delivery systems, while those with a diameter of a few tens of microns have been widely used in various engineering applications and medical and pharmaceutical applications, providing weight reduction of the material and improved thermal and acoustical insulation. In this study, uniformly sized hollow polylactic acid (PLA) microcapsules with diameters of 10–20 μm and 1–2 μm have been fabricated by two different methods, both based on the nature of microbubbles. One method is based on the growth and/or coalescence of microbubbles inside microdroplets of PLA organic solution dispersed in a continuous aqueous phase, and the other one is based on the spontaneous release of independent microbubbles covered with PLA from millidroplets into the continuous phase. Neither of these methods uses microfluidic devices, and they have thus high potential for mass production without compromising the uniformity.