Ionic reservoir at electrode surface

Claim 2

An electrode membrane combination comprising an electrode and a membrane comprising a closely packed array of amphiphilic molecules and a plurality of ionophores, the membrane is connected to the electrode by means of a linker molecule(s) in a manner such that a hydrophilic space is provided between the membrane and the electrode, the space allows the flux of ions through the ionophores, the linker molecule comprising within the same molecule a hydrophobic region attached to or embedded in the membrane, an attachment region attached to the electrode and a hydrophilic region intermediate said hydrophobic and attachment regions and spanning said space between the membrane and the electrode, wherein the hydrophobic region is selected from the group consisting of dioleyl glutamate, di(X) glutamate where X is an alkyl chain between 12-20 carbon atoms in length selected from the group consisting of, glycerol didodecanoate, glycerol ditetradecanoate, glycerol dihexadecanoate, glycerol dioctadecanoate, glycerol dioleate, archaebacterial lipid, synthetic membranes spanning archaebacterial lipid mimics and membrane compatible ion channels; the attachment region is selected from the group consisting of thiol, disulphide, sulphide, thione, xanthate, phosphine, isonitrile and silyl groups, and the hydrophilic region of the linker molecule is selected from the group consisting of an oligo/ethylene oxide group consisting of 4 to 20 ethylene oxide units or 1-4 sub-units of tetraethylene glycol attached to succinic acid or 1 to 4 succinic acid/1 to 4 diesterified, 1,2,3,4-butanetetraol subunits.

Claim 3

An electrode membrane combination as claimed in claim 1 in which the distance between the membrane and the electrode is in the range 10 to 1000 Å.

Claim 4

An electrode membrane combination as claimed in claim 1 in which the space between the membrane and the electrode is in the range 15-100 Å.

Claim 5

An electrode membrane combination as claimed in claim 1 in which the hydrophobic region of the linker molecule constitutes at least a proportion of the amphiphilic molecules making up the membrane.

Claim 6

An electrode membrane combination as claimed in claim 1 in which the hydrophobic region of the linker molecule contains polymerisable groups.

Claim 7

An electrode membrane combination as claimed in claim 1 in which the hydrophobic region is gramicidin.

Claim 8

An electrode membrane combination as claimed in claim 1 in which the linker molecule comprises a benzyl disulphide attachment region, a hydrophilic region composed, in sequence of tetraethylene glycol, succinic, tetraethylene glycol and succinic acid subgroups and a hydrophobic region of dioleylglutamate.

Claim 9

An electrode membrane combination as claimed in claim 1 in which the linker molecule comprises a symmetrical disulphide attachment region, a hydrophilic region composed, in sequence of tetraethylene glycol, succinic acid, tetraethylene glycol and succinic acid subgroups and a hydrophobic region composed of cholesterol.

Claim 10

An electrode membrane combination as claimed in claim 1 in which the linker molecule comprises a symmetrical disulphide attachment region, a hydrophilic region composed, in sequence, of tetraethylene glycol and succinic acid subgroups and a hydrophobic region composed of 1,2-glycerol ditetradecanoate.

Claim 11

An electrode membrane combination as claimed in claim 1 in which the linker molecule comprises a symmetrical disulphide attachment region, a hydrophilic region comprising, in sequence, of tetraethylene glycol and succinic acid subgroups and a hydrophobic region composed of dioleylglutamate.

Claim 12

An electrode membrane combination as claimed in claim 1 in which the linker molecule comprises a thiol or disulphide attachment region, a hydrophilic region composed, in sequence, of mercaptoethanol, succinic acid, 1,4-diesterified 1,2,3,4-butanetetraol and succinic acid subunits and a hydrophobic region of 1,2-glycerol ditetradecanoate.

Claim 13

An electrode membrane combination as claimed in claim 1 in which the linker molecule comprises a benzyl disulphide attachment region, a hydrophilic region composed, in sequence, of tetraethylene glycol, succinic acid, tetraethylene glycol, succinic acid, and a hydrophobic region of 1,1'-dotriacontamethylenebis(2-hexadecyl-sn-glycerol and a head group consisting of glycine, 1,6-amino caproic acid and biotin.

Claim 14

An electrode membrane combination as claimed in claim 1 in which the linker molecule comprises a benzyl disulfide attachment region, a hydrophilic region composed, in sequence, of tetraethylene glycol, succinic acid, tetraethylene glycol, succinic acid, tetraethylene glycol, succinic acid and a hydrophobic region of gramicidin.

Claim 15

An electrode membrane combination as claimed in claim 1 in which the ionophores is gramicidin.

Claim 16

An electrode membrane combination as claimed in claim 1 in which the ionophores are gated such that in the presence of an analyte the conductance of the membrane is altered.

Claim 17

A method of assaying for the presence of an analyte in a sample comprising contacting the electrode membrane combination as claimed in claim 15 in which the ionophores are gated with the sample and measuring the conductivity.

Claim 18

A linker molecule for use in attaching a membrane to an electrode and providing a space between the membrane and the electrode, the linker molecule comprising, within the same molecule: (i) a hydrophobic region selected from the group consisting of dioleyl glutamate, di(X) glutamate where X is an alkyl chain between 12-20 carbon atoms in length, selected from the group consisting of glycerol didodecanoate, glycerol ditetradecanoate, glycerol dihexadecanoate, glycerol dioctadecanoate, glycerol dioleate, archaebacterial lipid, synthetic membranes spanning archaebacterial lipid mimics and membrane compatible ion channels; (ii) a hydrophilic region selected from the group consisting of an oligo/ethylene oxide group consisting of 4 to 20 ethylene oxide units or 1-4 sub-units of tetraethylene glycol attached to succinic acid or 1 to 4 succinic acid/1 to 4 diesterified, 1,2,3,4-butanetetraol subunits; (iii) an attachment region selected from the group consisting of thiol, disulphide, sulphide, thione, xanthate, phosphine, isonitrile and silyl groups.

Claim 19

A linker molecule for use in attaching a membrane to an electrode and providing a space between the membrane and the electrode, the linker molecule comprising, within the same molecule: (i) a hydrophobic region selected from the group consisting of dioleyl glutamate, di(X) glutamate where X is an alkyl chain between 12-20 carbon atoms in length, selected from the group consisting of glycerol didodecanoate, glycerol ditetradecanoate, glycerol dihexadecanoate, glycerol dioctadecanoate, glycerol dioleate, archaebacterial lipid, synthetic membranes spanning archaebacterial lipid mimics and membrane compatible ion channels; (ii) a hydrophilic region selected from the group consisting of an oligo/ethylene oxide group consisting of 4 to 20 ethylene oxide units or 1-4 sub-units of tetraethylene glycol attached to succinic acid or 1 to 4 succinic acid/1 to 4 diesterified, 1,2,3,4-butanetetraol subunits; (iii) an attachment region selected from the group consisting of thiol, disulphide, sulphide, thione, xanthate, phosphine, isonitrile and silyl groups.

Claim 20

A linker molecule as claimed in claim 17 in which the hydrophobic region is gramicidin.

Claim 21

A linker molecule as claimed in claim 17 in which the linker molecule comprises a benzyl disulphide attachment region, a hydrophilic region composed, in sequence of tetraethylene glycol, succinic, tetraethylene glycol and succinic acid subgroups and a hydrophobic region of dioleylglutamate.

Claim 22

A linker molecule as claimed in claim 17 in which the linker molecule comprises a symmetrical disulphide attachment region, a hydrophilic region composed, in sequence of tetraethylene glycol, succinic acid, tetraethylene glycol and succinic acid subgroups and a hydrophobic region composed of cholesterol.

Claim 23

A linker molecule as claimed in claim 17 in which the linker molecule comprises a symmetrical disulphide attachment region, a hydrophilic region composed, in sequence, of tetraethylene glycol and succinic acid subgroups and a hydrophobic region composed of 1,2-glycerol ditetradecanoate.

Claim 24

A linker molecule as claimed in claim 17 in which the linker molecule comprises a symmetrical disulphide attachment region, a hydrophilic region comprising, in sequence, of tetraethylene glycol and succinic acid subgroups and a hydrophobic region composed of dioleylglutamate.

Claim 25

A linker molecule as claimed in claim 17 in which the linker molecule comprises a thiol or disulphide attachment region, a hydrophilic region composed, in sequence, of mercaptoethanol, succinic acid, 1,4-diesterified 1,2,3,4-butanetetraol and succinic acid subunits and a hydrophobic region of 1,2-glycerol ditetradecanoate.

Claim 26

A linker molecule as claimed in claim 17 in which the linker molecule comprises a benzyl disulphide attachment region, a hydrophilic region composed, in sequence, of tetraethylene glycol, succinic acid, tetraethylene glycols, succinic acid, and a hydrophobic region of 1,1'dotriacontamethylenebis(2-hexadecyl-sn-glycerol and a head group consisting of glycine, 1,6-amino caproic acid and biotin;

Claim 27

A linker molecule as claimed in claim 17 in which the linker molecule comprises a benzyl disulfide attachment region, a hydrophilic region composed, in sequence, of tetraethylene glycol, succinic acid, tetraethylene glycol, succinic acid, tetraethylene glycol, succinic acid and a hydrophobic region of gramicidin.

Claim 28

An ion selective electrode comprising an electrode and a membrane comprising a closely packed array of amphiphilic molecules and a plurality of ionophores selected from the group consisting of valinomycin, crown ether analogues and ion selective ion channels, the membrane is connected to the electrode by means of a linker molecule(s) in a manner such that a hydrophilic space is provided between the membrane and the electrode, the space allows the flux of ions through the ionophores, the linker molecule comprising within the same molecule a hydrophobic region which constitutes at least a proportion of the amphiphilic molecules making up the membrane or is attached to or is embedded in the membrane, an attachment region attached to the electrode and a hydrophilic region intermediate said hydrophobic and attachment regions and spanning said space between the membrane and the electrode, wherein the hydrophobic region is selected from the group consisting of dioleyl glutamate, di(X) glutamate where X is an alkyl chain between 12-20 carbon atoms in length, selected from the group consisting of glycerol didodecanoate, glycerol ditetradecanoate, glycerol dihexadecanoate, glycerol dioctadecanoate, glyceroldioleate, archaebacterial lipid, synthetic membranes spanning archaebacterial lipid mimics and membrane compatible ion channels; the attachment region is selected from the group consisting of thiol, disulphide, sulphide, thione, xanthate, phosphine, isonitrile and silyl groups, and the hydrophilic region of the linker molecule being selected from the group consisting of an oligo/ethylene oxide group consisting of 4 to 20 ethylene oxide units or 1-4 sub-units of tetraethylene glycol attached to succinic acid, or 1 to 4 succinic acid/1 to 4 diesterified, 1,2,3,4,-butanetetraol subunits.

Claim 29

An ion selective electrode comprising an electrode and a membrane comprising a closely packed array of amphiphilic molecules and a plurality of ionophores selected from the group consisting of valinomycin, crown ether analogues and ion selective ion channels, the membrane is connected to the electrode by means of a linker molecule(s) in a manner such that a hydrophilic space is provided between the membrane and the electrode, the space allows the flux of ions through the ionophores, the linker molecule comprising within the same molecule a hydrophobic region which constitutes at least a proportion of the amphiphilic molecules making up the membrane or is attached to or is embedded in the membrane, an attachment region attached to the electrode and a hydrophilic region intermediate said hydrophobic and attachment regions and spanning said space between the membrane and the electrode, wherein the hydrophobic region is selected from the group consisting of dioleyl glutamate, di(X) glutamate where X is an alkyl chain between 12-20 carbon atoms in length, selected from the group consisting of glycerol didodecanoate, glycerol ditetradecanoate, glycerol dihexadecanoate, glycerol dioctadecanoate, glyceroldioleate, archaebacterial lipid, synthetic membranes spanning archaebacterial lipid mimics and membrane compatible ion channels; the attachment region is selected from the group consisting of thiol, disulphide, sulphide, thione, xanthate, phosphine, isonitrile and silyl groups, and the hydrophilic region of the linker molecule being selected from the group consisting of an oligo/ethylene oxide group consisting of 4 to 20 ethylene oxide units or 1-4 sub-units of tetraethylene glycol attached to succinic acid, or 1 to 4 succinic acid/1 to 4 diesterified, 1,2,3,4,-butanetetraol subunits.

Claim 32

A method as claimed in claim 27 in which a second membrane layer is assembled onto the coated electrode by contacting the coated electrode with a solution of lipid containing a C 8 -C 16 alkane or squalene in a carrier solvent which allows partitioning of the alkane/lipid and which is water soluble.

Claim 33

A method as claimed in claim 28 in which the alkane is selected from the group consisting of N-decane, hexadecane and squalene.