Electrostatically induced planar lipid membrane formation on a cationic hydrogel array by the fusion of small negatively charged unilamellar vesicles

Abstract

Abstract A membrane protein is one of the targets for understanding cellular function and for biosensor and drug screening applications. An artificial lipid membrane suspended over microwells can act as a platform when we attempt to realize a nanobio device based on a membrane protein function. With the aim of preparing a lipid membrane array on a substrate, we investigated lipid membrane formation on a hydrogel-confined micropatterned substrate because a hydrogel can support a lipid membrane both mechanically and functionally. The interaction between the positive charge of the hydrogel and the negative charge of the substrate surface allows the hydrogel to be confined in the microwells. When small unilamellar vesicles with a diameter smaller than the aperture of the microwells were added to the solution over the substrate, hydrogel-supported lipid membranes were formed. The vesicle fusion was facilitated by the electrostatic interaction between the vesicle charge and the opposite charge of the hydrogel. The continuous and fluid properties of the hydrogel-supported lipid membrane were confirmed by the fluorescent recovery after photobleaching method. Our results suggest that support provided by hydrogels in the microwells enables us to arrange membrane proteins on a nanobio device by the direct formation of a planar lipid membrane from proteoliposomes with a small diameter.