Zein/luteolin microparticles formation using a supercritical fluids assisted technique

In this work, a supercritical-based process, named Supercritical Assisted Injection in a Liquid Antisolvent (SAILA), has been proposed for the entrapment of an antioxidant, luteolin, in zein microparticles. Zein submicro and micrometric particles, with an average size between 0.26 and 2 μm, were obtained using ethanol-water mixtures as solvent with composition ranging from 70/30 to 90/10 volume ratio. Then, the experiments for the coprecipitation of zein/luteolin were performed. Using SAILA, zein/luteolin microparticles with a mean diameter of 1.20 ± 0.20 ÷ 1.26 ± 0.17 μm and good entrapment efficiencies, up to 82%, were obtained. The coprecipitates were characterized by a homogeneous drug dispersion in the polymer matrix. The antioxidant activity of coprecipitated particles was comparable to the one of luteolin in native state. Coprecipitates showed faster dissolution rate (2 ÷ 3 h) with respect to the physical mixture zein/luteolin (20h), with a consequent increase in luteolin bioavailability.