Lipid Bilayers on a Picoliter Microdroplet Array for Rapid Fluorescence Detection of Membrane Transport

Abstract

This paper describes picoliter-sized lipid bilayer chambers and their theoretical model for the rapid detection of membrane transport. To prepare the chambers, semispherical aqueous droplets are patterned on a hydrophilic/hydrophobic substrate and then brought into contact with another aqueous droplet in lipid-dispersed organic solvent, resulting in the formation of the lipid bilayers on the semispherical droplets. The proposed method implements the lipid bilayer chambers with 25-fold higher ratio of lipid membrane area (S) to chamber volume (V) compared to the previous spherical droplet chambers. Using these chambers, we are able to trace the time-course of Ca(2+) influx through α-hemolysin pores by a fluorescent indicator. Moreover, we confirm that the detection time of the substrate transport is inversely proportional to the S/V ratio of the developed chambers, which is consistent with the simulation results based on the developed model. Our chambers and model might be useful for rapid functional analyses of membrane transport phenomena.

Large scale patterning of hydrogel microarrays using capillary pinning

“…Picoliter volume hydrogel microarray patterning is a promising unique method with great potential for biological and clinical applications, such as subdivided-hydrogel microarrays for bacteria cultures 31,32 and 3D cell cultures, 33 and enclosed hydrogel microarrays for electrokinetic biomolecule separation purposes. 34 Although our demonstration is limited to hydrogel formation, patterning of aqueous solutions would be equally possible, for example enabling massively parallel liquid 35 and droplet 36 patterning in microfluidic devices, and liquid compartmentalization for sensing and bioassays. 37…”

Droplet microfluidics for synthetic biology

“…Droplets may also be formed on a patterned substrate surface, providing easy compartmentalization of biological molecules and reagents without complex instrumentation. 15 An additional technique, microfluidic jetting, provides the compartmentalization of biomolecules in a phospholipid membrane, and is used in artificial cell applications. 16 …”

Rotational chambers on fluidic channels for the repetitive formation of optically observable lipid-bilayer membranes

“…However, the method is hardly compatible with microscope observation of the bilayer, because the bilayer is formed in a vertical manner to a focal plane of a microscope. Although there were some methods for optical observable bilayer [8][9][10][11][12][13][14], it is impossible to simply reform the lipid bilayer with the methods. We recently reported a device that formed optically observable lipid bilayer based on the droplets contact method [15].…”