The preparation, evaluation and phase behavior of linker-based coix seed oil microemulsion

Abstract

Coix seed oil (CSO) is a kind of fatty oil extracted from coix seed, which has broad anticancer effects. Using CSO as the oil phase in a microemulsion (ME) system can replace the conventional oil phase with a medicinal oil and reduce the use of chemical materials. Medium- and short-chain alcohols are typically used as a cosurfactant in conventional ME, but it may cause adverse reactions. It is necessary to prepare alcohol-free ME. One alternative to alcohol-free preparation is the use of linker molecules. In this study, an emodin-loaded, linker-based CSO ME (Em-L-CSO-ME) was prepared. EL-35 was used as the surfactant, Span-80 was used as the lipophilic linker, acetic acid/sodium acetate was used as the hydrophilic linker, CSO was used as the oil phase and water was used as the aqueous phase. The droplet size of Em-L-CSO-ME was 37.96 ± 0.52 nm, the PDI was 0.13 ± 0.04, the Zeta potential was −0.94 ± 0.20 mV, and the entrapment efficiency was 93.36 ± 0.83%. Analysis of the rate of cancer cell inhibition using A549 cells showed that Em-L-CSO-ME inhibited the proliferation of A549 cells in a dose-dependent manner. Additionally, Em-L-CSO-ME worked just as effectively as ME prepared with conventional cosurfactants. Then, particle dissipation dynamics (DPD) was used to study the phase behavior of the linker-based CSO ME (L-CSO-ME). The results showed that the phase behavior of L-CSO-ME may be related to the interaction between phases, which was enhanced by linker molecules and increased the solubility of the CSO. DPD directly reflected the phase behavior of the linker molecule that promoted the formation of the ME, which is difficult to prove experimentally. The results showed that the linker could provide an alternative preparation strategy for CSO ME.