Determination of an analyte in a liquid medium

Claim 1

A system for determining binding between a first and a second member of a recognition pair, said recognition pair being a pair selected from the group consisting of antigen-antibody, ligand-receptor, sugar-lectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell, the system comprising: (a) a probe comprising a piezoelectric crystal, electrodes on two opposite faces of said crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising said first member of a recognition pair, wherein binding of said second member of the recognition pair to said immobilized first member, or dissociation of a prior bound recognition pair and release of said second member from said probe, causes a change of mass resulting in a change in the resonance frequency of said probe; (b) a vessel for holding a liquid, wherein said probe is immersed in said liquid to allow either binding between said immobilized first member and a second member dissolved in said liquid, or release of said second member bound to said first member in a prior bound recognition pair, into said liquid; and (c) an electric or electronic circuitry for generating an alternating electric field between said electrodes, for measuring the resonance frequency of said crystal, and for determining a change in the resonance frequency of said probe and deducing therefrom the occurrence of either binding between said immobilized first member and a dissolved second member or release of said second member, bound to said immobilized first member in a prior bound recognition pair, into said liquid, wherein said immobilized first member is immobilized on a surface of said metal plates by means of a linking group, having the following general formula (I): Z—R 1 —Q  (I) wherein: Z represents a sulphur-containing moiety which chemically associates with, attaches to, or chemisorbs onto the surface of said metal plates; R 1 represents a connecting group; Q is a functional group which forms a covalent bond with a moiety of said immobilized first member of said recognition pair.

Claim 2

A system for determining binding between a first and a second member of a recognition pair, said recognition pair being a pair selected from the group consisting of antigen-antibody, ligand-receptor, sugar-lectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell, the system comprising: (a) a probe comprising a piezoelectric crystal, electrodes on two opposite faces of said crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising said first member of a recognition pair, wherein binding of said second member of the recognition pair to said immobilized first member, or dissociation of a prior bound recognition pair and release of said second member from said probe, causes a change of mass resulting in a change in the resonance frequency of said probe; (b) a vessel for holding a liquid, wherein said probe is immersed in said liquid to allow either binding between said immobilized first member and a second member dissolved in said liquid, or release of said second member bound to said first member in a prior bound recognition pair, into said liquid; and (c) an electric or electronic circuitry for generating an alternating electric field between said electrodes, for measuring the resonance frequency of said crystal, and for determining a change in the resonance frequency of said probe and deducing therefrom the occurrence of either binding between said immobilized first member and a dissolved second member or release of said second member, bound to said immobilized first member in a prior bound recognition pair, into said liquid, wherein said immobilized first member is immobilized on a surface of said metal plates by means of a linking group, having the following general formula (I): Z—R 1 —Q  (I) wherein: Z represents a sulphur-containing moiety which chemically associates with, attaches to, or chemisorbs onto the surface of said metal plates; R 1 represents a connecting group; Q is a functional group which forms a covalent bond with a moiety of said immobilized first member of said recognition pair.

Claim 3

A system for determining binding between a first and a second member of a recognition pair, said recognition pair being a pair selected from the group consisting of antigen-antibody, ligand-receptor, sugar-lectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell, the system comprising: (a) a probe comprising a piezoelectric crystal, electrodes on two opposite faces of said crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising said first member of a recognition pair, wherein binding of said second member of the recognition pair to said immobilized first member, or dissociation of a prior bound recognition pair and release of said second member from said probe, causes a change of mass resulting in a change in the resonance frequency of said probe; (b) a vessel for holding a liquid, wherein said probe is immersed in said liquid to allow either binding between said immobilized first member and a second member dissolved in said liquid, or release of said second member bound to said first member in a prior bound recognition pair, into said liquid; and (c) an electric or electronic circuitry for generating an alternating electric field between said electrodes, for measuring the resonance frequency of said crystal, and for determining a change in the resonance frequency of said probe and deducing therefrom the occurrence of either binding between said immobilized first member and a dissolved second member or release of said second member, bound to said immobilized first member in a prior bound recognition pair, into said liquid, wherein said immobilized first member has or is linked to an isomerizable group which changes its isomerization state as a result of exposure to energy, said isomerizable group having a first and a second isomerization state and converts from said first state to said second state by exposure to a first energy type and from said second state to said first state upon exposure to a second energy type, wherein, in said first state, said immobilized first member has a high affinity of binding to said second member, and in said second state, said immobilized first member has a low affinity of binding to said second member.

Claim 4

A system for determining binding between a first and a second member of a recognition pair, said recognition pair being a pair selected from the group consisting of antigen-antibody, ligand-receptor, sugar-lectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell, the system comprising: (a) a probe comprising a piezoelectric crystal, electrodes on two opposite faces of said crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising said first member of a recognition pair, wherein binding of said second member of the recognition pair to said immobilized first member, or dissociation of a prior bound recognition pair and release of said second member from said probe, causes a change of mass resulting in a change in the resonance frequency of said probe; (b) a vessel for holding a liquid, wherein said probe is immersed in said liquid to allow either binding between said immobilized first member and a second member dissolved in said liquid, or release of said second member bound to said first member in a prior bound recognition pair, into said liquid; and (c) an electric or electronic circuitry for generating an alternating electric field between said electrodes, for measuring the resonance frequency of said crystal, and for determining a change in the resonance frequency of said probe and deducing therefrom the occurrence of either binding between said immobilized first member and a dissolved second member or release of said second member, bound to said immobilized first member in a prior bound recognition pair, into said liquid, wherein said immobilized first member has or is linked to an isomerizable group which changes its isomerization state as a result of exposure to energy, said isomerizable group having a first and a second isomerization state and converts from said first state to said second state by exposure to a first energy type and from said second state to said first state upon exposure to a second energy type, wherein, in said first state, said immobilized first member has a high affinity of binding to said second member, and in said second state, said immobilized first member has a low affinity of binding to said second member.

Claim 7

A method for determining an analyte in a liquid medium, comprising the steps of: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of said probe, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising a first member of a recognition pair, said recognition pair being selected from the group consisting of antigen-antibody, ligand-receptor, sugar-lectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell, said second member of said recognition pair being non-covalently bound to said immobilized first member, said second member binding to an analyte, wherein the binding between said second member and said analyte is competitive with the binding of said second member to said immobilized first member; (b) measuring an initial resonance frequency of said probe; (c) contacting said probe with a liquid medium under conditions and for an amount of time such that, in the presence of said analyte in said liquid medium, at least some of said second member non-covalently bound to said first member will be released and bind to said analyte; and (d) measuring a second resonance frequency, whereby a higher second resonance frequency as compared to the initial resonance frequency, which results from a decrease in mass of said probe, as a consequence of release of said second member into said liquid medium, indicates the presence of said analyte in said liquid medium.

Claim 8

A method for determining an analyte in a liquid medium, comprising the steps of: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of said probe, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising a first member of a recognition pair, said recognition pair being selected from the group consisting of antigen-antibody, ligand-receptor, sugar-lectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell, said second member of said recognition pair being non-covalently bound to said immobilized first member, said second member binding to an analyte, wherein the binding between said second member and said analyte is competitive with the binding of said second member to said immobilized first member; (b) measuring an initial resonance frequency of said probe; (c) contacting said probe with a liquid medium under conditions and for an amount of time such that, in the presence of said analyte in said liquid medium, at least some of said second member non-covalently bound to said first member will be released and bind to said analyte; and (d) measuring a second resonance frequency, whereby a higher second resonance frequency as compared to the initial resonance frequency, which results from a decrease in mass of said probe, as a consequence of release of said second member into said liquid medium, indicates the presence of said analyte in said liquid medium.

Claim 12

A method for determining binding between a first member of a recognition pair and a second member of a recognition pair, said recognition pair being a pair selected from the group consisting of antigen-antibody, ligand-receptor, sugar-pectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell, said second member being initially contained in a liquid medium, comprising the steps of: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of said crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising said first member of said recognition pair; (b) measuring an initial resonance frequency of said probe; (c) contacting said probe with a liquid medium containing said second member for an amount of time sufficient to allow binding between said first member and said second member; and (d) measuring a second resonance frequency, whereby a lower second resonance frequency, as compared to the initial resonance frequency, which results from an increase in mass of said probe as a consequence of said binding, indicates the presence of said second member in said liquid medium, wherein said immobilized first member is immobilized on a surface of said metal plate by a linking group, having the following general formula (I): Z—R 1 Q  (I) wherein: Z represents a sulphur-containing moiety which chemically associates with, attaches to, or chemisorbs onto the surface of said metal plate; R 1 represents a connecting group; Q is a functional group which forms a covalent bond with a moiety of said first member of said recognition pair.

Claim 13

A method for determining binding between a first member of a recognition pair and a second member of a recognition pair, said recognition pair being a pair selected from the group consisting of antigen-antibody, ligand-receptor, sugar-pectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell, said second member being initially contained in a liquid medium, comprising the steps of: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of said crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising said first member of said recognition pair; (b) measuring an initial resonance frequency of said probe; (c) contacting said probe with a liquid medium containing said second member for an amount of time sufficient to allow binding between said first member and said second member; and (d) measuring a second resonance frequency, whereby a lower second resonance frequency, as compared to the initial resonance frequency, which results from an increase in mass of said probe as a consequence of said binding, indicates the presence of said second member in said liquid medium, wherein said immobilized first member is immobilized on a surface of said metal plate by a linking group, having the following general formula (I): Z—R 1 Q  (I) wherein: Z represents a sulphur-containing moiety which chemically associates with, attaches to, or chemisorbs onto the surface of said metal plate; R 1 represents a connecting group; Q is a functional group which forms a covalent bond with a moiety of said first member of said recognition pair.

Claim 14

A method for determining binding between a first member of a recognition pair and a second member of a recognition pair, said recognition pair being a pair selected from the group consisting of antigen-antibody, liqand-receptor, sugar-pectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell, said second member being initially contained in a liquid medium, comprising the steps of: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of said crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising said first member of said recognition pair; (b) measuring an initial resonance frequency of said probe; (c) contacting said probe with a liquid medium containing said second member for an amount of time sufficient to allow binding between said first member and said second member; and (d) measuring a second resonance frequency, whereby a lower second resonance frequency, as compared to the initial resonance frequency, which results from an increase in mass of said probe as a consequence of said binding, indicates the presence of said second member in said liquid medium, wherein said immobilized first member has or is linked to a group which changes its isomerization state as a result of exposure to energy, said group having a first and a second isomerization state and converts from said first state to said second state upon exposure to a first energy type and from said second state to said first state upon exposure to a second energy type, wherein, in said first state, said immobilized first member has a high affinity of binding to said second member, and in said second state, said immobilized first member has a low affinity of binding to said second member.

Claim 15

A method for determining binding between a first member of a recognition pair and a second member of a recognition pair, said recognition pair being a pair selected from the group consisting of antigen-antibody, liqand-receptor, sugar-pectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell, said second member being initially contained in a liquid medium, comprising the steps of: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of said crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising said first member of said recognition pair; (b) measuring an initial resonance frequency of said probe; (c) contacting said probe with a liquid medium containing said second member for an amount of time sufficient to allow binding between said first member and said second member; and (d) measuring a second resonance frequency, whereby a lower second resonance frequency, as compared to the initial resonance frequency, which results from an increase in mass of said probe as a consequence of said binding, indicates the presence of said second member in said liquid medium, wherein said immobilized first member has or is linked to a group which changes its isomerization state as a result of exposure to energy, said group having a first and a second isomerization state and converts from said first state to said second state upon exposure to a first energy type and from said second state to said first state upon exposure to a second energy type, wherein, in said first state, said immobilized first member has a high affinity of binding to said second member, and in said second state, said immobilized first member has a low affinity of binding to said second member.

Claim 16

A method for determining an analyte in a liquid medium, comprising: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of the crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising an immobilized first member bound to a second member of a recognition pair, said second member being capable of binding to an analyte, wherein the binding between said second member and said analyte being competitive to the binding of said second member to said immobilized first member, said recognition pair being selected from a group consisting of antigen-antibody, ligand-receptor, sugar-lectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell; (b) measuring an initial resonance frequency of said probe; (c) mixing a liquid medium with a solution containing said second member to form a mixture, whereby the presence of said analyte in said liquid medium causes binding of said analyte to said second member; (d) contacting the mixture obtained in step (c) with said probe for an amount of time sufficient to allow binding of said second member to said immobilized first member; and (e) measuring a second resonance frequency of said probe, whereby a second resonance frequency lower than the initial frequency indicates binding of said second member to said immobilized first member with a consequent increase of mass of said probe, and deducing therefrom the presence of said analyte in said liquid medium, wherein said analyte is a molecule suspended or dissolved in a gas, the method further comprising the step of passing a gas containing a sample of suspended or dissolved molecules through a liquid to determine the presence of said analyte in said liquid.

Claim 17

A method for determining an analyte in a liquid medium, comprising: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of the crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising an immobilized first member bound to a second member of a recognition pair, said second member being capable of binding to an analyte, wherein the binding between said second member and said analyte being competitive to the binding of said second member to said immobilized first member, said recognition pair being selected from a group consisting of antigen-antibody, ligand-receptor, sugar-lectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell; (b) measuring an initial resonance frequency of said probe; (c) mixing a liquid medium with a solution containing said second member to form a mixture, whereby the presence of said analyte in said liquid medium causes binding of said analyte to said second member; (d) contacting the mixture obtained in step (c) with said probe for an amount of time sufficient to allow binding of said second member to said immobilized first member; and (e) measuring a second resonance frequency of said probe, whereby a second resonance frequency lower than the initial frequency indicates binding of said second member to said immobilized first member with a consequent increase of mass of said probe, and deducing therefrom the presence of said analyte in said liquid medium, wherein said analyte is a molecule suspended or dissolved in a gas, the method further comprising the step of passing a gas containing a sample of suspended or dissolved molecules through a liquid to determine the presence of said analyte in said liquid.

Claim 18

A method for determining an analyte in a liquid medium, comprising: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of the crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising an immobilized first member bound to a second member of a recognition pair, said second member being capable of binding to an analyte, wherein the binding between said second member and said analyte being competitive to the binding of said second member to said immobilized first member, said recognition pair being selected from a group consisting of antigen-antibody, ligand-receptor, sugar-lection, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell; (b) measuring an initial resonance frequency of said probe; (c) mixing a liquid medium with a solution containing said second member to form a mixture, whereby the presence of said analyte in said liquid medium causes binding of said analyte to said second member; (d) contacting the mixture obtained in step (c) with said probe for an amount of time sufficient to allow binding of said second member to said immobilized first member; and (e) measuring a second resonance frequency of said probe, whereby a second resonance frequency lower than the initial frequency indicates binding of said second member to said immobilized first member with a consequent increase of mass of said probe, and deducing therefrom the presence of said analyte in said liquid medium, wherein said immobilized first member is immobilized on a surface of said metal plate by a linking group, having the following general formula (I): Z—R 1 Q  (I) wherein: Z represents a sulphur-containing moiety which chemically associates with, attaches to, or chemisorbs onto the surface of said metal plate; R 1 represents a connecting group; Q is a functional group which forms a covalent bond with a moiety of said first member of said recognition pair.

Claim 19

A method for determining an analyte in a liquid medium, comprising: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of the crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising an immobilized first member bound to a second member of a recognition pair, said second member being capable of binding to an analyte, wherein the binding between said second member and said analyte being competitive to the binding of said second member to said immobilized first member, said recognition pair being selected from a group consisting of antigen-antibody, ligand-receptor, sugar-lection, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell; (b) measuring an initial resonance frequency of said probe; (c) mixing a liquid medium with a solution containing said second member to form a mixture, whereby the presence of said analyte in said liquid medium causes binding of said analyte to said second member; (d) contacting the mixture obtained in step (c) with said probe for an amount of time sufficient to allow binding of said second member to said immobilized first member; and (e) measuring a second resonance frequency of said probe, whereby a second resonance frequency lower than the initial frequency indicates binding of said second member to said immobilized first member with a consequent increase of mass of said probe, and deducing therefrom the presence of said analyte in said liquid medium, wherein said immobilized first member is immobilized on a surface of said metal plate by a linking group, having the following general formula (I): Z—R 1 Q  (I) wherein: Z represents a sulphur-containing moiety which chemically associates with, attaches to, or chemisorbs onto the surface of said metal plate; R 1 represents a connecting group; Q is a functional group which forms a covalent bond with a moiety of said first member of said recognition pair.

Claim 20

A method for determining an analyte in a liquid medium, comprising: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of the crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising an immobilized first member bound to a second member of a recognition pair, said second member being capable of binding to an analyte, wherein the binding between said second member and said analyte being competitive to the binding of said second member to said immobilized first member, said recognition pair being selected from a group consisting of antigen-antibody, ligand-receptor, sugar-lectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell; (b) measuring an initial resonance frequency of said probe; (c) mixing a liquid medium with a solution containing said second member to form a mixture, whereby the presence of said analyte in said liquid medium causes binding of said analyte to said second member; (d) contacting the mixture obtained in step (c) with said probe for an amount of time sufficient to allow binding of said second member to said immobilized first member; and (e) measuring a second resonance frequency of said probe, whereby a second resonance frequency lower than the initial frequency indicates binding of said second member to said immobilized first member with a consequent increase of mass of said probe, and deducing therefrom the presence of said analyte in said liquid medium, wherein said immobilized first member has or is linked to a group which changes its isomerization state as a result of exposure to energy, said group having a first and a second isomerization state and converts from said first state to said second state upon exposure to a first energy type and from said second state to said first state upon exposure to a second energy type, wherein, in said first state, said immobilized first member has a high affinity of binding to said second member, and in said second state, said immobilized first member has a low affinity of binding to said second member.

Claim 21

A method for determining an analyte in a liquid medium, comprising: (a) providing a probe comprising a piezoelectric crystal, electrodes on two opposite faces of the crystal, and one or more metal plates carried on the surface of said crystal, said metal plates being the same or different than said electrodes and having immobilized thereon by chemical association, chemical attachment or chemisorption a monolayer comprising an immobilized first member bound to a second member of a recognition pair, said second member being capable of binding to an analyte, wherein the binding between said second member and said analyte being competitive to the binding of said second member to said immobilized first member, said recognition pair being selected from a group consisting of antigen-antibody, ligand-receptor, sugar-lectin, biotin-avidin, enzyme-substrate, oligonucleotide-oligonucleotide with a complementary sequence, oligonucleotide-protein, and oligonucleotide-cell; (b) measuring an initial resonance frequency of said probe; (c) mixing a liquid medium with a solution containing said second member to form a mixture, whereby the presence of said analyte in said liquid medium causes binding of said analyte to said second member; (d) contacting the mixture obtained in step (c) with said probe for an amount of time sufficient to allow binding of said second member to said immobilized first member; and (e) measuring a second resonance frequency of said probe, whereby a second resonance frequency lower than the initial frequency indicates binding of said second member to said immobilized first member with a consequent increase of mass of said probe, and deducing therefrom the presence of said analyte in said liquid medium, wherein said immobilized first member has or is linked to a group which changes its isomerization state as a result of exposure to energy, said group having a first and a second isomerization state and converts from said first state to said second state upon exposure to a first energy type and from said second state to said first state upon exposure to a second energy type, wherein, in said first state, said immobilized first member has a high affinity of binding to said second member, and in said second state, said immobilized first member has a low affinity of binding to said second member.