Investigations of drug binding ability of a trisubstituted surface active ionic liquid 1-dodecyl-2,3-dimethylimidazolium chloride [C12bmim][Cl]

Self-assembling and interactional behavior of a trisubstituted imidazolium based surface active ionic liquid (SAIL), 1-dodecyl-2,3-dimethylimidazolium chloride [C12bmim][Cl], with anesthetic drugs lidocaine hydrochloride (HCl) and procaine hydrochloride (HCl) have been screened using surface tension and fluorescence measurements at 298.15 K and from conductance at 288.15, 298.15 and 308.15 K. Critical aggregation concentration (CAC), ionization degree (α), and various thermodynamic parameters were achieved using conductivity measurements. The various associated interfacial parameters of IL at different compositions of the drugs have been evaluated using surface tension. A detailed analysis of the microenvironment of the aggregates and the size of the aggregates was done by using fluorescence spectroscopy technique. The CAC values decreases as the concentration of the drug increases, which is due to the balancing between hydrophobic and electrostatic interactions. This study confirms the presence of strong synergistic interactions between SAIL and drugs and formation of highly stable drug-SAIL complexes by a conjunction of hydrophobic, hydrophilic, electrostatic and cation-π interactions with 1:1 stoichiometry. A comparative study between disubstituted and trisubstituted SAILs with lidocaine HCl have also been discussed in this paper. Surface activity of trisubstituted SAIL has been found better than their disubstituted analogue due to the high hydrophobicity and hydrophilicity of the former.