Formation of Layers of Amphiphilic Molecules

Abstract

To form a layer separating two volumes of aqueous solution, there is used an apparatus comprising elements defining a chamber, the elements including a body of non-conductive material having formed therein at least one recess opening into the chamber, the recess containing an electrode. A pre-treatment coating of a hydrophobic fluid is applied to the body across the recess. Aqueous solution, having amphiphilic molecules added thereto, is flowed across the body to cover the recess so that aqueous solution is introduced into the recess from the chamber and a layer of the amphiphilic molecules forms across the recess separating a volume of aqueous solution introduced into the recess from the remaining volume of aqueous solution.

Description

RELATED APPLICATIONS[0001]The present application claims priority to United Kingdom Patent Application No. 0724736.4 filed on Dec. 19, 2007. The present application also claims priority to U.S. Provisional Patent Application Ser. No. 61 / 080,492 filed Jul. 14, 2008. The entire contents of the above referenced applications are incorporated herein by reference.FIELD OF THE DISCLOSURE[0002]In one aspect, the present disclosure relates to the formation of layers of amphiphilic molecules such as lipid bilayers. It is particularly concerned with the formation of high quality layers suitable for applications requiring measurement of electrical signals with a high degree of sensitivity, for example single channel recordings and stochastic sensing for biosensor or drug screening applications. In some aspects, it is concerned with applications employing arrays of layers of amphiphilic molecules, for example lipid bilayers. In another aspect, the present disclosure relates to the performance of...

AI Technical Summary

Benefits of technology

[0051]The application of the pre-treatment coating may leave excess hydrophobic fluid covering said electrode contained in the recess. This potentially insulates the electrode by reducing ionic flow, thereby reducing the sensitivity of the apparatus in measuring electrical signals. However various different techniques may be applied to minimize this problem.

[0052]A first technique may comprise applying a voltage across an electrode in a recess and a further electrode in the chamber sufficient to reduce the amount of excess hydrophobic fluid co...

Problems solved by technology

However there are many technical challenges to overcome in developing this technology to fully realise the potential.

While the requirements for stochastic sensing have been met in the laboratory, the conditions and expertise required limit its use.

In addition, the laboratory methods are laborious and time-consuming and are not easily scalable to high-density arrays, which are desirable for any commercial biosensor.

Furthermore, the fragility of single bilayer membranes means that anti-vibration tables are often employed in the laboratory.

Thinning of the solvent results in formation of a lipid bilayer, however, complete removal of the solvent from the bilayer is difficult and consequently the bilayer formed is less stable and more noise prone during measurement.

Problems with the reproducibility of bilayer formation are attributed to the difficulty in removing the excess hydrophobic material from the aperture, and tackled by using a period of air exposure to aid the bilayer formation process to thin the pre-treatment.

This presents a number of difficulties for scaling up the system to a large number of individually addressable bilayers, as at least one of the aqueous chambers must be a distinct chamber with no electrical or ionic connectivity to any other chamber.

Sandison et al. created a device with three fluid chambers, each with separate fluidics, an approach which would be difficult to scale to large numbers of bilayers.

In this case, it is difficult to control the flow of solution across the aperture containing interface and the use of small volumes exposed to air makes the apparatus susceptible to evaporation effects.

However, the approach has a number of drawbacks, the first is that the small aqueous volume present under the lipid bilayer, typically of the order of 1 nm to 10 nm thick, does not contain enough ions to perform a direct current measurement for any useful period of time.

For recordings of any meaningful duration, an alternating current measurement must be used to overcome the ionic depletion at the electrode, but that limits the sensitivity of the device.

In this system, the wells created by this process could not be individually addr...

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