10.1021/jp512212u.s001 Pritam Guha Pritam Guha Biplab Roy Biplab Roy Gourab Karmakar Gourab Karmakar Prasant Nahak Prasant Nahak Suraj Koirala Suraj Koirala Manish Sapkota Manish Sapkota Takeshi Misono Takeshi Misono Kanjiro Torigoe Kanjiro Torigoe Amiya Kumar Panda Amiya Kumar Panda Ion-Pair Amphiphile: A Neoteric Substitute That Modulates the Physicochemical Properties of Biomimetic Membranes American Chemical Society 2015 Thermal behavior sodium dodecyl sulfate hexadecyltrimethylammonium bromide 100 days EE HTMAB scanning calorimetry hydrodynamic diameter hydrocarbon chain vesicle Such formulations novel drug delivery systems cationic dye methylene MB novel substitute Physicochemical Properties polydispersity index solution behavior IPA concentration SLC SDS Entrapment efficiency 2015-03-19 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Ion_Pair_Amphiphile_A_Neoteric_Substitute_That_Modulates_the_Physicochemical_Properties_of_Biomimetic_Membranes/2184871 Ion-pair amphiphiles (IPAs) are neoteric pseudo-double-tailed compounds with potential as a novel substitute of phospholipid. IPA, synthesized by stoichiometric/equimolar mixing of aqueous solution of hexadecyltrimethylammonium bromide (HTMAB) and sodium dodecyl sulfate (SDS), was used as a potential substituent of naturally occurring phospholipid, soylecithin (SLC). Vesicles were prepared using SLC and IPA in different ratios along with cholesterol. The impact of IPA on SLC was examined by way of surface pressure (π)–area (<i>A</i>) measurements. Associated thermodynamic parameters were evaluated; interfacial miscibility between the components was found to depend on SLC/IPA ratio. Solution behavior of the bilayers, in the form of vesicles, was investigated by monitoring the hydrodynamic diameter, zeta potential, and polydispersity index over a period of 100 days. Size and morphology of the vesicles were also investigated by electron microscopic studies. Systems comprising 20 and 40 mol % IPA exhibited anomalous behavior. Thermal behavior of the vesicles, as scrutinized by differential scanning calorimetry, was correlated with the hydrocarbon chain as well as the headgroup packing. Entrapment efficiency (EE) of the vesicles toward the cationic dye methylene blue (MB) was also evaluated. Vesicles were smart enough to entrap the dye, and the efficiency was found to vary with IPA concentration. EE was found to be well above 80% for some stable dispersions. Such formulations thus could be considered to have potential as novel drug delivery systems.