Solvent-Assisted Lipid Bilayer Formation on Au Surfaces: Effect of Lipid Concentration on Solid-Supported Membrane Formation

摘要

Solvent-assisted lipid bilayer (SALB) formation is emerged as a versatile approachin forming supported lipid membranes (SLBs) on metal surfaces, interestingplatforms for transducing a biological signal to an electrical readout where vesiclerupture is not straightforward. Herein, the effect of the lipid concentration in theorganic solvent, a key parameter controlling SALB, is addressed in the low andhigh concentration limits of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine lipid ona Au surface. Quartz crystal microbalance with dissipation (QCM-D) responsesare correlated with atomic force microscopy (AFM) topographic and nanomechanicalmeasurements. Upon SALB completion at both concentrations, QCM-Dand AFM topographical characterization suggest the formation of thin, althoughincomplete, lipid layers at the Au–liquid interface, with frequency and dissipationplateau values departing from well-established homogeneous SLB responses.Nanomechanical analysis reveals the presence of mostly monolayers at lowconcentration due to lack of lipid material, while at high concentration excess oflipid material leads to the coexistence of diverse structures. Their formationstems from the SALB formation mechanism, based on lyotropic transformationsupon solvent exchange, which differs from customarily vesicle rupture. Suchmechanism leads to peculiar two-step features in approach force curves on SLBspointing toward a decoupling in bilayer leaflets when supported.