Methods of assay
First Claim
1. In a homogeneous method of electrochemical assay of a ligand in a sample using an electrochemical apparatus having at least a working electrode and and auxiliary electrode and containing components comprising:
- (a) the sample,(b) a specific binding partner to the ligand and at least one further reagent selected from ligand analogues and specific binding partners to the ligand, one of the components (b) being labelled with an oxidoreductase enzyme, and(c) a substrate for the enzyme, the improvement which comprises said apparatus additionally containing an electron transfer chemical capable of aiding the transfer of electrons between the substrate and the working electrode via the enzyme as a result of oxidation or reduction of the substrate but which is not essential for the activity of said enzyme, and the method including the step of determining whether the said transfer of electrons is perturbed by formation of a complex of said ligand with at least one specific binding partner.
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Accused Products
Abstract
An electrochemical specific binding assay of a ligand (e.g., antigen, hapten or antibody) wherein at least one of the components is enzyme-labelled, and which includes the step of determining the extent to which the transfer of electrons between the enzyme substrate and an electrode, associated with the substrate reaction, is perturbed by complex formation or by displacement of any ligand complex relative to unbound enzyme-labelled component.
The electron transfer is aided by electron-transfer mediators which can accept electrons from the enzyme and donate them to the electrode or vice versa (e.g. ferrocene) or by electron-transfer promoters which retain the enzyme in close proximity with the electrode without themselves taking up a formal charge.
The electrochemical apparatus will typically comprise two or three electrodes, including one working electrode onto which components may advantageously be immobilized.
The use of direct electrochemical measurement of the enzyme label avoids the errors and inconvenience of the known indirect measurement techniques.
64 Citations
22 Claims
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1. In a homogeneous method of electrochemical assay of a ligand in a sample using an electrochemical apparatus having at least a working electrode and and auxiliary electrode and containing components comprising:
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(a) the sample, (b) a specific binding partner to the ligand and at least one further reagent selected from ligand analogues and specific binding partners to the ligand, one of the components (b) being labelled with an oxidoreductase enzyme, and (c) a substrate for the enzyme, the improvement which comprises said apparatus additionally containing an electron transfer chemical capable of aiding the transfer of electrons between the substrate and the working electrode via the enzyme as a result of oxidation or reduction of the substrate but which is not essential for the activity of said enzyme, and the method including the step of determining whether the said transfer of electrons is perturbed by formation of a complex of said ligand with at least one specific binding partner. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A kit for carrying out a method of assay comprising in separate containers:
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(i) at least one specific binding partner to the ligand or a specific binding partner to the ligand and at least one further reagent selected from ligand analogs and specific binding partners to the ligand, one of the components (i) being labelled with an oxidoreductase enzyme, (ii) a substrate for the enzyme and (iii) an electron transfer chemical capable of aiding the transfer of electrons between the substrate and an electrode via the enzyme as a result of oxidation or reduction of the substrate. - View Dependent Claims (13)
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14. In a heterogeneous method of electrochemical assay of a ligand in a sample using an electrochemical apparatus having at least a working electrode and an auxiliary electrode and containing components comprising:
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(a) the sample (b) a specific binding partner to the ligand or a specific binding partner to the ligand and at least one further reagent selected from ligand analogues and specific binding partners to the ligand, one of the components (b) being labelled with an oxidoreductase enzyme, and (c) a substrate for the enzyme, the improvement which comprises said apparatus additionally containing an electron transfer chemical capable of aiding the transfer of electrons between the substrate and the working electrode via the enzyme as a result of oxidation or reduction of the substrate but which is not essential for the activity of said enzyme, and the method including the steps of providing means for separation of any enzyme-labelled complex containing said ligand relative to any other enzyme-labelled component, or where an enzyme-labelled ligand analog is present as component (b) providing means for separation of any complex containing said ligand analog relative to non-complexed enzyme-labelled ligand analog, and determining whether the said transfer of electrons is thereby perturbed. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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Specification