Detailed physicochemical and computational investigation are made to explore different aspects of complexation between bovine serum albumin (BSA) and three structurally different surface active ionic liquids (SAILs), 1-dodecyl-3-methylimidazolium chloride, [C12mim][Cl]; 3-(2-(dodecylamino)-2-oxoethyl)-1-methyl-1H-imidazol-3-ium chloride, [C12Amim][Cl] and 3-methyl-1-dodecyloxy carbonyl methylimidazolium chloride, [C12Emim][Cl]. The interfacial and bulk complexation behavior has been monitored using tensiometry, conductivity, steady-state fluorescence and turbidity measurements. Thermodynamic insights about complexation have been obtained using isothermal titration calorimetry (ITC) measurements whereas molecular docking studies were used to predict the possible binding sites of SAILs on BSA. The information obtained from these studies helped in establishing the formed BSA-SAIL complex as a pH dependent colloidal transport system for controlled transport of a lipophilic dye, Rhodamine 6G (R6G), in aqueous phase, which is supported by confocal laser scanning microscopy (CLSM). In the present work, the effect of functionalization over the alkyl chain of SAILs, modulating the colloidal properties of SAIL-BSA systems, has been explored along with the utilization of these complexes as a pH dependent reversible carrier of lipophilic molecules. It is expected that besides providing basic understanding of colloidal complexes of BSA with SAILs, the present work is expected to be helpful in extending the applications of such colloidal systems for material transport.
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