Abstract
Fatty acid nanoparticles containing hinokitiol (HKL) were prepared by a melt-emulsification method. Behenic acid (BA) was used as a lipid for the matrix material of the nanoparticle. The size distribution was quite mono-dispersive and the mean diameter was around 200 nm. On a differential scanning calorimeter, no endothermic peak of HKL was observed when it was encapsulated in the nanoparticles. This indicates that HKL in the lipid matrix of the nanoparticles is not in a crystalline state, but rather in a dissolved state. The nanoparticles were stable over the range of pH 2–10 in terms of size. The absolute values of the zeta potentials in the pH range were high enough to prevent a particle-to-particle aggregation. Compared with stearic acid (SA) nanoparticles, which were completely disintegrated in sodium lauryl sulfate (SLS) solution of 4%, the BA nanoparticles were robust and remained intact even in SLS solutions of 14%. Therefore, BA nanoparticles would be applicable to cleansing products containing detergents for personal care. When encapsulated either in SA nanoparticles or in BA nanoparticles, the in vitro flux of HKL through hairless mouse skin was 10–15 times higher than dissolved in propylene glycol. BA nanoparticles, however, enhanced the transdermal delivery of HKL less than SA nanoparticles did.
This work was supported by a grant (KRF-2007-314-C00271) from Korea Research Foundation, Republic of Korea.