Effect of rapid expansion of subcritical solutions processing conditions on loading capacity of tetrahydrocurcumin encapsulated in poly(l-lactide) particles

Abstract

Encapsulation of tetrahydrocurcumin (THC) in poly(l-lactide) (PLLA) was achieved by rapid expansion of subcritical solutions of THC and PLLA into water. A pressurized mixture consisting of ethanol and carbon dioxide (3:2 wt/wt) was used as a solvent for THC and PLLA with concentrations up to 2 wt%. The influences of pre-expansion conditions (temperature and pressure) and THC:PLLA weight ratio on the size and morphology of THC-loaded PLLA particles, as well as the loading capacity of THC, were systematically investigated. All the obtained particles were spherical in shape with average size and THC loading capacity ranges of ∼80-110 nm and ∼13-25%, respectively. The loading capacity increased with (i) increasing pre-expansion temperature and reducing pre-expansion pressure and (ii) increasing THC:PLLA weight ratio at high pre-expansion temperature and low pre-expansion pressure. The antioxidant activity of THC remained unchanged after rapid expansion process, and encapsulation in PLLA prolonged the release of THC.