Probing molecular interactions of tetracaine with surface active ionic liquid and subsequent formation of vesicle in aqueous medium

Abstract

We present a study which establish the basic understanding of molecular interactions between an local anesthetic amphiphilic drug, tetracaine (TC) and surface active ionic liquid (SAIL), 1-hexyl-3-methylimidazolium dodecylsulfate ([C6mim][C12OSO3]) in aqueous medium of buffer at pH7. The synergistic interactions between TC and [C6mim][C12OSO3] at air-water interface as well as in bulk were monitored using surface tension and conductivity techniques respectively. Micellar, interfacial and thermodynamic parameters have been evaluated for the TC-[C6mim][C12OSO3] catanionic mixture. The perturbations in fluorescence and absorption spectra of TC upon addition of [C6mim][C12OSO3] clearly indicates the formation of TC-[C6mim][C12OSO3] catanionic complex with 1:1 stoichiometry. The combined analysis of techniques concluded that addition of TC delays the [C6mim][C12OSO3] micellization as it prefer to get solubilised in micellar core due to the existence of strong electrostatic interactions, hydrophobic interactions and hydrogen bonding. Here, we have also reported the transition of prolate ellipsoid micelles formed by [C6mim][C12OSO3] into vesicles upon addition of TC at varying mole fractions using small angle neutron scattering (SANS) and dynamic light scattering (DLS) measurements. Hence, the results of this work expected to be very useful in understanding drug-SAIL interactions responsible for the formation of supramolecular aggregates which offers many applications in drug delivery.