Impact of Inulin on Self-Assembled Behavior of Anionic Surface Active Ionic Liquids: Conductometric, Spectroscopic and Antimicrobial Studies

Abstract

The self-assembled behavior of greener anionic surface-active ionic liquids (SAILs), namely Tetrapropylammonium Dodecylsulfate (TPADS) and Tetrabutylammonium Dodecylsulfate (TBADS), in an aqueous solution of biocompatible saccharide inulin, has been extensively investigated using conductometric and fluorescence probe techniques at different temperatures. The critical micellar concentration (CMC) values have been determined by observing the breakage point in κ vs. [SAIL] plots. These values as obtained from fluorescence probe techniques have also been calculated. It has been found that the CMC values obtained through both conventional and spectroscopic techniques exhibited close agreement. Additionally, thermodynamic parameters of micellization, such as Gibbs free energy (ΔGmo), enthalpy (ΔHmo), and entropy (ΔSmo) were calculated using conductivity data as they play a crucial role in understanding the various interactions prevailing in the SAIL-inulin-water system. It was found that the micellization process for SAILs in the aqueous inulin solution occurs readily, as indicated by the Gibbs free energy of micellization. Furthermore, the antimicrobial properties of biocompatible SAILs in 0.2% w/w aqueous inulin solution were explored against bacterial strains, gram-positive i.e. B. cereus, S. aureus, and gram-negative namely P. aeruginosa. Molecular docking studies were also conducted to determine the binding energy and binding sites between TBADS and the proteins of the aforementioned bacteria. These investigations help to enhance the understanding of potential applications and interactions of SAILs in the presence of inulin.