Abstract
Bio-based surface-active ionic liquids (SAILs) offer promising advantages for pharmaceutical applications, particularly in enhancing drug solubility and bioavailability. Aspirin, classified under the Biopharmaceutics Classification System (BCS) as poorly soluble in the gastrointestinal tract, require effective solubilization strategies for improved therapeutic efficacy. This study investigates the micellization behavior and thermophysical properties of three natural based SAILs (2-hydroxyethyl)ammonium oleate ([2-HEA][Ole]), bis(2-hydroxyethyl)ammonium oleate ([BHEA][Ole]), and tris(2-hydroxyethyl)ammonium oleate ([THEA][Ole]) in aqueous solutions of aspirin at 298 K. Micellization characteristics, including critical micelle concentration (CMC), were determined using electrical conductivity and surface tension measurements for SAILs in the presence of the aspirin aqueous solutions systems at 298 K. Key interfacial parameters such as interface surface pressure (Π), minimum surface area occupied per molecule ([Formula: see text]), Gibbs maximum excess surface concentration ([Formula: see text]) were also calculated. Additionally, the Conductor-like Screening Model (COSMO) was employed to elucidate molecular interactions between SAILs and the studied drug. The results indicate that CMC values decrease in the presence of aspirin. Among the studied systems, [THEA][Ole] exhibited the lowest CMC, as determined by electrical conductivity and surface tension measurements, particularly in the presence of higher concentrations of aspirin in aqueous media. Furthermore, COSMO analysis revealed that [THEA][Ole], possessing the highest surface cavity volume (V), demonstrated the most favorable interactions with aspirin, highlighting its potential as an effective solubilizing agent. Finally, interactions between SAILs and aspirin were investigated through limiting molar conductivity [Formula: see text] , and association constant [Formula: see text] , determination.