Serono Diagnostics Ltd.

Other

Simon J Rattle

Grenville Arthur Robinson

Gordon C Forrest

Hugh A Hill

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.

Methods of assay

A method of assaying a ligand in a sample which method includes the steps of contacting the sample with components comprising

Use of charge transfer complexes in assay

In its broadest aspect, the present invention provides a method of effecting an electrochemical specific-binding assay of a ligand, either qualitatively or quantitatively, in an apparatus comprising at leasts one electrode, in which method a labelled component of the assay medium is, at least in part, magnetically held in the vicinity of the electrode. The electrochemical assay method may include a separation step, whereby bound label may be separated from free label in the assay medium. Preferably the electrochemical assay method will include the step of determining a perturbation in an electrochemical characteristic of components of the assay medium associated with a ligand complexing reaction. Such an assay method is applicable to, for example, antibodies and antigens and suitable labels include redox centers, enzyme labels in the presence of an electron-transfer mediator and electron-transfer mediator labels in the presence of an electron donor or acceptor.

Method of assay employing a magnetic electrode

A ligand in a sample can be assayed using electrochemical apparatus containing a working electrode and components comprising:

Electrochemical methods of assay

In its broadest aspect, the present invention provides a method of assaying a ligand in a sample which comprises contacting the sample with a predetermined quantity of a specific binding partner to the ligand, said specific binding partner being immobilized on the effective gate electrode of a field effect transistor, and determining whether (and, if desired, the extent to which) an appropriate transistor characteristic is changed as a result of complex formation between the ligand and the specific binding partner.

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Quainton, United Kingdom

Simon J Rattle