Micellar structural transitions and therapeutic properties in tea tree oil solubilized pluronic P123 solution

Abstract

Pluronics are used in industry as solubilizing agents for a variety of lipophilic compounds. The influence of different lipophiles on aggregation characteristics of Pluronics quite expectedly remained a subject of fundamental interest for the last few decades. In this manuscript, we show that solubilization of tea tree essential oil (TTO) brings about spherical-to-worm like micelles-to-vesicular structural transitions in aqueous solutions of Pluronic P123. TTO exhibits broad-spectrum antimicrobial properties and have therapeutic potential for wide range of diseases ranging from common wounds to different forms of cancers. Its solubilization in Pluronic solutions was carried out by subjecting the aqueous TTO-Pluronic systems into heat cycling through their phase separation temperature. We suggest that accelerated dynamics of micellar restructuring process in Pluronic P123 solutions at high temperature is responsible for solubilization of TTO upon heat cycling. Such instances of oil solubilization upon heat treatment and subsequent systematic micellar structural transitions are first of its kind in aqueous systems of nonionic surfactants. TTO solubilized Pluronic solutions exhibit antimicrobial property and cytotoxicity to breast (MCF7) and lung (A549) cancer cells, which suggest that therapeutic activity of TTO is not destroyed upon heating induced micellar solubilization.