Direct observation of interactions between supported lipid bilayers and surfactants

A mechanistic understanding of the interactions between surfactants and biomembranes is important to achieve hygiene benefits from external pathogens and chemical irritants. Supported lipid bilayers (SLBs), which are versatile platforms for mimicking envelopes and cell membranes, are widely used to study detergent dynamics at bio-nano interfaces. However, studies on the effect of a surfactant structure on SLBs are scarce, and it remains unclear how a surfactant solubilizes SLBs in real time from a morphological perspective. In this study, we prepared a SLB of L-α phosphatidylcholine at a water/aminopropyltriethoxysilane-coated silicon wafer interface and compared its transformation and desorption due to contact with aqueous solution of three surfactants, anionic sodium dodecyl sulfate (SDS), sodium N-dodecanoyl-N-methyl taurate (SDMT), and nonionic octaethyleneglycol monododecyl ether (C₁₂EO₈). A combined analysis using high-speed atomic force microscopy and the quartz crystal microbalance with dissipation monitoring technique evidenced that SDS instantaneously solubilized lipids via adsorption and insertion of SDS molecules to the SLB, whereas SDMT was reversibly adsorbed on the SLB surface without any change in the morphology of the SLB. This discrepancy can be attributed to the function and configuration of the taurate moiety in SDMT as a barrier to membrane partitioning. C₁₂EO₈ gradually disturbed the SLB morphology owing to spontaneously induced curvature changes in the SLB upon incorporation. This solubilized the lipid layers with slower kinetics as compared to that with the SDS detergent. Our findings provide a clue to the scientific understanding of the influence of additives on lipids during viral and cell disruption, which has potential implications in toiletry and cosmetics industries.