METHOD OF ASSAY USING DIRECT MONITORING OF ENZYME LABEL

摘要

Methods of Assay An electrochemical specific binding assay of a ligand (e.g. antigen, hapten or antibody) wherein at least one of the components is enzymelabelled, 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 and/or by controlled external influences. The electron transfer is aided by electrontransfer 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 immobilised. When controlled external influences are employed, they may comprise displacement of the complex formed relative to the unbound enzyme-labelled component. The use of direct electrochemical measurement of the enzyme label avoids the errors and inconvenience of the known indirect measurement techniques.