Chemistry: electrical and wave energy – Apparatus – Electrolytic
Patent
1991-04-18
1993-08-10
Niebling, John
Chemistry: electrical and wave energy
Apparatus
Electrolytic
204418, 204416, 204426, 435817, 436806, G01N 2726
Patent
active
052345661
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates generally to biosensors comprising membranes including at least one ion channel. In one form of the invention the conductance of the ion channels is dependent on electric field applied across the membrane. In addition, the present invention relates to biosensors comprising discrete arrays of membranes, each membrane including at least one ion channel, and the conductance of each membrane being measurable independently.
BACKGROUND OF THE INVENTION
It is known that amphiphilic molecules may be caused to aggregate in solution to form two or three dimensional ordered arrays such as monolayers, micelles, black lipid membranes, and vesicles or lisosomes, which vesicles may have a single compartment or may be of the multilamellar type having a plurality of compartments.
The selectivity and flux of ions through membranes can depend on the number, size and detailed chemistry of the pores or channels that they possess. It is through these pores or channels that permeating solute molecules pass across the membrane.
It is known that membranes may incorporate a class of molecules, called ionophores, which facilitate the transport of ions across these membranes. Ion channels are a particular form of ionophore, which as the term implies are channels through which ions may pass through membranes. The measurement of current flow across membranes due to a single ion channel is known and typically yields a current of 4 pA per channel.
The use of membranes including ion channels in biosensors has been proposed. In co-pending International Patent Application No. W089/01159 (published 9 Feb. 1989) the production of biosensors incorporating membranes including ion channels is disclosed. The disclosure of this application is hereby incorporated by way of cross-reference. The present invention seeks to provide biosensors of greater sensitivity.
DESCRIPTION OF THE PRESENT INVENTION
The present invention consists in a biosensor comprising at least one lipid membrane each membrane including at least one gated ion channel, each of said membranes comprising a closely packed array of self-assembling amphiphilic molecules, said at least one gated ion channel having a conductance which is dependent upon an electric field applied across the membrane.
In a preferred embodiment of this aspect of the present invention, the biosensor comprises a plurality of discrete lipid membranes, the conductance of each membrane being measurable independently of the conductance of the other membranes.
In a second aspect the present invention consists in a biosensor comprising a plurality of discrete membranes, each membrane including at least one gated ion channel, each of said membranes comprising a closely packed array of self-assembling amphiphilic molecules, the conductance of each of said membranes being measurable independently of the conductance of the other membranes.
As used herein the term "gated ion channel" is defined as an ion channel the passage of ions through which is dependent on the presence of an analyte.
As used herein the term "field effect ion channel" is defined as an ion channel in which the conductance of the ion channel is dependent on an electric field applied across a membrane incorporating the ion channel.
The amphiphilic molecules are normally surfactant molecules having a hydrophilic "head" portion and one or more hydrophobic "tails". Surfactants may be any of the known types, i.e. cationic (e.g. quaternary ammonium salts), anionic (e.g. organosulfonate salts), zwitterionic (e.g. phosphatidyl cholines, phosphatidyl ethanolamines), membrane spanning lipid, or non-ionic (e.g. polyether materials). The amphiphilic molecules are preferably such that they can be cross-linked. For this purpose it is necessary to provide the molecules with a cross-linkable moiety such as vinyl, methacrylate, diacetylene, isocyano or styrene groups either in the head group or in the hydrophobic tail. Such groups are preferably connected to the amphiphilic molecule through a spacer group such
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Cornell Bruce A.
King Lionel G.
Osman Peter D. J.
Raguse Burkhard
Australian Membrane and Biotechnology Research Institute Ltd.
Bell Bruce F.
Niebling John
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