Three-Dimensional Construction of Bilayer Networks using Shape Encoded Hydrogel

Abstract

The newly invented system - droplet interface bilayer (DIB) - is beginning to emerge as a versatile platform not only for studying the basic properties of membrane proteins but also to construct novel nano-devices. Small volumes of aqueous buffer when injected into hexadecane take the form of droplets. These droplets when loaded with lipids assemble a lipid monolayer at the water/oil interface. By carefully touching two such monolayer encased aqueous droplets a bilayer can be formed which is conducive to the insertion of membrane proteins.Here we demonstrate that contacting two hydrogel surfaces coated with lipid monolayers can form a lipid bilayer, forming a so-called hydrogel interface bilayer (HIB). We use two of the most commonly available hydrogels, a natural polymer agarose and a synthetic polymer polyethylene glycol diacrylate (PEG-DA), to form HIBs. The lipid bilayers formed using both the polymers are conducive to the insertion of membrane proteins as shown by the insertion of α-hemolysin pore.Thus far, solid-supported lipid bilayers for reconstituting membrane proteins have been assembled in a 2-D plane. We present a simple approach to form lipid monolayers on a manipulable 3-D system based on hydrogels. Millimeter sized particles were formed by using low melt agarose or PEG-diacrylate. Agarose and PEG-DA based hydrogels can be molded in different shapes and coated with a lipid monolayer, which on bringing together gives a lipid bilayer as monitored by an increase in the capacitance. Polymers molded in different shapes have been used in a number of applications ranging from reaction coding in enzyme catalysis to providing a 3-D environment for cell growth to drug delivery. We propose the use of such solid particles incorporating membrane pores for the use of constructing communicating electrical devices.