Suspended Planar Phospholipid Bilayers on Micromachined Supports

Abstract

Micromachined structures consisting of an aperture between a buried reservoir and ambient have been produced using the photoresist SU8. The external surface of the structure, surrounding the aperture, was coated in a gold layer to allow surface modification with self-assembled monolayers. These structures were assessed as substrates for the assembly of "suspended" phospholipid bilayers. We report that phospholipid bilayer membranes could be formed over such apertures and that they are highly resistive to the conduction of metal anions (K + ). Resistance values are typically found to be ∼10 10 Ω (∼10 6 Ω cm 2 ). These values represent a significant improvement over our membranes supported directly on gold substrates (10 5 Ω cm 2 ). Fluorescence microscopy images are presented to provide evidence that the lipid bilayer spans the 100 µm aperture. Given the ease of producing large numbers of devices using microlithographic techniques, the proposed structures could form a sensing element for studying membrane transport phenomena in general and for ion-channel assays in particular.

Fluorophore-Encapsulated Solid-Supported Bilayer Vesicles: A Method for Studying Membrane Permeation Processes

“…These systems have many advantages but do not always lend themselves to studies of protein binding with the membrane and can be complex and difficult to fabricate. 7 One potential approach for improving the properties of biomimetic bilayers is to tether whole vesicles to a solid support. The advantage of such a system is that vesicles combine the relatively high electrical resistance of a lipid bilayer with the fluidity of a cellular biomembrane.…”

4 Electrochemistry of Biomimetic Membranes

“…Evans' group reported a device consisting of a 100 m micromachined hole in a gold surface suspended over an aqueous reservoir. An octadecanethiol 104 or perfluorothiol monolayer 105 was tethered to the gold surface, to impart a hydrophobicity similar to that of the bilayer-forming solution to the hole rim. A lipid bilayer was then painted across the aperture with a plastic stick.…”

Nanoscale Biosensors and Biochips

“…For an in-depth review of the many suggested membrane sensor platforms, we refer the reader to a recent review by Janshoff and Steinem [111] or to topical reviews on specific configurations [112,113]. The first developed and most widespread in vitro method for studying ion-channel function is the bilayer lipid membrane (BLM), spanning across apertures between two aqueous compartments [114]. While a successful approach under laboratory conditions, this platform has a few major drawbacks for general application: (i) instability manifested in the collapse of the membrane within a few hours of preparation; (ii) preparation requiring solvents which stay in the membrane, making it incompatible with many proteins which alter conformation and function in the presence of solvent; and (iii) limited to only electrochemical and fluorescence based sensing techniques.…”