Synthesis, Self-Aggregation, Interfacial Behavior and Interaction Studies of Non- Cytotoxic Caffeinium-Based Surface Active Ionic Liquids with Sodium Dodecyl Sulfate

Caffeinium-based surface-active ionic liquids (SAILs), (1-(2-alkanoyl oxy) ethylcaffeinium bromide), [C(n)Ecaf]Br with variable chain length (n=12, 14, 16) were synthesized and their molecular structures were explored by multiple spectral techniques. The critical micelle concentration (CMC) of pure SAILs and their mixtures with sodium dodecyl sulfate (SAIL-DS) in aqueous solution was determined by employing various techniques at 298 K. The tensiometry and dynamic light scattering (DLS) techniques have been employed to gain insight about the interfacial behavior and aggregate size of cat-anionic mixtures in aqueous solution. Interestingly, the interaction parameters (X-1(m),beta(m)) showed strong synergism between these two oppositely charged molecules. Further, it was found that SAIL-DS cat-anionic mixtures exhibit excellent adsorption efficacy and are more effective in lowering the surface tension of water as compared to pure SAILs. The DLS results showed the formation of mixed-size aggregates in SAIL-DS systems. The contact angle and wetting properties of pure SAILs over the parafilm surface were also determined using a static sessile drop method. Further, MTT assay was used to determine the biocompatibility of SAILs on Human embryonic kidney (HEK-293) cell line and in-vitro anti-cancer activity on Lung cancer cells (A549). These SAILs displayed substantial cytotoxicity against cancerous cells, indicating that they could be useful in a variety of biological applications.