Using a patterned grating structure to create lipid bilayer platforms insensitive to air bubbles

Abstract

Supported lipid bilayers (SLBs) have been used for various biosensing applications. The bilayer structure enables embedded lipid membrane species to maintain their native orientation, and the two-dimensional fluidity is crucial for numerous biomolecular interactions to occur. The platform integrated with a microfluidic device for reagent transport and exchange has great potential to be applied with surface analytical tools. However, SLBs can easily be destroyed by air bubbles during assay reagent transport and exchange. Here, we created a patterned obstacle grating structured surface in a microfluidic channel to protect SLBs from being destroyed by air bubbles. Unlike all of the previous approaches using chemical modification or adding protection layers to strengthen lipid bilayers, the uniqueness of this approach is that it uses the patterned obstacles to physically trap water above the bilayers to prevent the air-water interface from directly coming into contact with and peeling the bilayers. We showed that our platform with certain grating geometry criteria can provide promising protection to SLBs from air bubbles. The required obstacle distance was found to decrease when we increased the air-bubble movement speed. In addition, the interaction assay results from streptavidin and biotinylated lipids in the confined SLBs suggested that receptors at the SLBs retained the interaction ability after air-bubble treatment. The results showed that the developed SLB platform can preserve both high membrane fluidity and high accessibility to the outside environment, which have never been simultaneously achieved before. Incorporating the built platforms with some surface analytical tools could open the bottleneck of building highly robust in vitro cell-membrane-related bioassays.

Mobile Lipid Bilayers on Gold Surfaces through Structure-Induced Lipid Vesicle Rupture

“…Other SLB formation methods usually require the proteins to be exposed to an air–water interface, detergent, or solvent, which may cause the proteins to denature . In addition, unlike other methods that can only allow SLB formation on the outer surface of an object, the vesicle deposition method enables SLB formation not only on the outer surface but also inside a flow chamber of a sensor chip. , However, there is a delicate interaction balance between supports and SLBs, and successful vesicle deposition for forming fluid SLBs has been reported on few types of surface, such as mica and silicon-based materials. ,,, Developing new methods for enabling lipid vesicles to deposit and form fluid SLBs on a wider variety of supports can facilitate using surface sensors to study cell-membrane-related events.…”

Subpicomolar Iron Sensing Platform Based on Functional Lipid Monolayer Microarrays

“…Given the tremendous potential of such lipid layer microarrays, miscellaneous techniques based on diffusion barriers, − microcontact printing, , noncontact printing, , optical lithography, , and lift-off , are currently used to create patterned substrates of lipid monolayers or bilayers. More recently, surface modification of Teflon has been demonstrated using e-beam lithography offering hindered areas that favor lipid adsorption and layer formation with areas of nanometric dimensions .…”