Binding Interactions Between Tetracaine Hydrochloride and Biocompatible Imidazolium-Based Gemini Surfactants in Aqueous Solutions

The low solubility of drugs in an aqueous medium causes their precipitation before reaching the specific target sites leading to various undesirable side effects. Thus, there is a need for designing and formulating delivery agents which not only carry a drug to its site of action but also improve its solubility. The study of interactions between a drug and its carrier becomes significant. Pertinently, the present study encompasses the interactions between aqueous solutions of a local anesthetic drug, tetracaine hydrochloride (TC) and a non-cytotoxic imidazolium gemini surfactant, [C n Im-3OH-ImC n ]Br 2 ( n = 12, 14, 16). The results were established on the basis of various parameters calculated from measurements using conductivity, fluorescence, UV–visible spectroscopy and cyclic voltammetry (CV). The parameters obtained from conductivity measurements showed attractive interactions (synergism) between TC and [C n Im-3OH-ImC n ]Br 2 whereas the UV–visible and CV measurements indicated a 1:1 stoichiometry in their complex formation. The binding of drug with gemini surfactants was found to decrease as the surfactant chain length increases. The hydrophobic, cation-π and H-bonding modes of interactions between drug and gemini surfactant aid in their binding process. The antibacterial activity of gemini surfactants was tested against both strains (gram-positive and gram-negative) of bacteria and found to be effective. Thus, these interaction studies offer new opportunities to bring about advancements in the biomedical and pharmaceutical fields.