Chaotropic Agent-Assisted Supported Lipid Bilayer Formation

Supported lipid bilayers (SLBs) are useful structures for mimicking cellular membranes, and they can be integrated with a variety of sensors. Although there are a variety of methods for forming SLBs, many of these methods come with limitations in terms of the lipid compositions that can be employed and the substrates upon which the SLBs can be deposited. Here we demonstrate the use of an all-aqueous chaotropic agent exchange process that can be used to form SLBs on two different substrate materials: SiO₂, which is compatible with traditional SLB formation by vesicle fusion, and Al₂O₃, which is not compatible with vesicle fusion. When examined with a quartz crystal microbalance with dissipation monitoring, the SLBs generated by chaotropic agent exchange (CASLBs) have similar frequency and dissipation shifts to SLBs formed by the vesicle fusion technique. The CASLBs block nonspecific protein adsorption on the substrate and can be used to sense protein-lipid interactions. Fluorescence microscopy was used to examine the CASLBs, and we observed long-range lateral diffusion of fluorescent probes, which confirmed that the CASLBs were composed of a continuous, planar lipid bilayer. Our CASLB method provides another option for forming planar lipid bilayers on a variety of surfaces, including those that are not amenable to the widely used vesicle fusion method.