Physicochemical Characterization of Surface-Active Ionic Liquid-Based Microemulsions for Enhanced Transdermal Delivery of Rutin

To achieve efficient transdermal delivery of rutin, a microemulsion (ME) system was developed by incorporating deep eutectic solvents (DES) as the inner phase and surface-active ionic liquids (SAILs) as surfactants. The DES used in this study is choline chloride/polyethylene glycol (PEG) 200, while the SAILs used were 1-alkyl-3-methylimidazolium bromides (Cn mimBr) with alkyl chain lengths of 10, 12, and 16 (C10 mimBr, C12 mimBr, C16 mimBr). Structural characterization by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) showed that MEs incorporated with C10 and C12 mimBr formed a cylindrical structure, where C16 mimBr formed spherical structures. MEs containing C10 or C12 mimBr exhibited significantly higher skin permeability of rutin, approximately 6.8 times greater compared with conventional water-in-oil (W/O) MEs. These results suggested that SAIL-based MEs are one of the promising drug carriers in the transdermal delivery of rutin.