(349b) Investigation of the Interaction between Switchable Cationic Surfactant and Phospholipid Bilayers

(S)-O-methyl-serine dodecylamide hydrochloride (MSDH) is a nonionic surfactant under neutral or basic conditions but switches to a protonated surfactant under acidic conditions. These switchable surfactants have been utilized for a variety of applications, such as drug delivery to cell apoptosis. Here, we probe the interactions between MSDH and with phospholipid bilayers. A number of analytical measurements, such as quartz crystal microbalance with dissipation (QCM-D), nanoplasmonic spectroscopy (NPS), and UV/Vis spectroscopy are utilized. The effect of surfactant concentration on the MSDH configuration at neutral and acidic pH is investigated. Of interest is the surfactant-lipid interactions under acidic conditions, when MSDH converts to cationic surfactant. We also examined the role of the various morphologies of the lipid bilayers: planer form and vesicle structure. The two different morphologies allowed us to probe and compare the equilibrium of surfactant-lipid bilayers by finding the surfactant/lipid ratio. Using that we identified the onset-solubilization concentration and completed-solubilization concentration of the surfactant. Combined all, we propose a three-stage-model which explains the possible mechanism of either surfactant-liposomes interaction or surfactant-supported lipid bilayers system.