Poly(lactic acid) Microencapsulation Prolongs the Mosquito Repellent Activity of Essential Oils from Thai Herbs

Abstract

In this research, biodegradable polylactic acid (PLA) was used to encapsulate 5 traditional Thai herb essential oils including lemon grass (Cymbopogon winterianus), bergamot (Citrus hystrix), turmeric (Curcuma longa), galangal (Alipinia galangal L.) and basil (Ocimum americanum) by using emulsification-solvent evaporation technique. After size and percent encapsulation of the PLA microcapsules containing essential oils have been analyzed, Aedes aegypti repellency of the PLA microcapsules have been determined using Excito-Repellency test kit compared with commercial mosquito repellent agent, N,N-diethyl-m-toluamide (DEET). It was found that the microcapsules showed less repellency than DEET at the beginning period. However, the repellency increases over time until it reached above DEET repellency after 60 minutes.  In the other hand, the repellency of all 5 non-encapsulated essential oils initially showed equal as DEET repellency but drastically decreased in 20-minute period while the DEET repellency slightly decreased. In conclusion, this PLA microencapsulation of essential oils is applicable to improve stability and control the releasing of essential oils under various usage conditions.