Release studies of essential oil of Thymus vulgaris L. from PLA microcapsules

The incorporation of essential oils, perfumes, deodorants and other active agents in microcapsules with the purpose of controlled release over a certain period of time is being a topic of considerable research in recent years. The controlled release systems are used to deliver compounds such us drugs, pesticides, fragrances or flavors at prescribed rates, together with improved efficacy, safety and convenience. Nowadays, core-shell microcapsules have been investigated extensively for utilization in controlled release systems, especially in drug delivery, where the polymeric wall is a permeable element with porosity that can determine the release behavior of core materials. The aim of this work is to study the release of essential oil of Thymus vulgaris L. (thyme oil) during the first days of release and develop a general diffusion model for predicting mass transport phenomena in biodegradable polymer microcapsules prepared by a coacervation technique. The release of this essential oil was investigated for microcapsules in solution by comparing calculated and experimental diffusion profiles of oil across de polymer membrane. Control of size and wall thickness of microcapsules and encapsulation efficiency were also studied.FCT within the PhD grant SFRH/BD/43215/200