Immunosensors for clinical diagnostics

Protein electrodes with direct electrochemical communication

Electrochemistry using direct electron transfer between an electrode and a protein or an enzyme has developed into a means for studying biological redox reactions and for bioanalytics, biosynthesis and bioenergetics. This review summarizes recent work on direct protein electrochemistry with special emphasis on our results in bioelectrocatalysis using isolated enzymes and enzyme-protein couples.

On-line flow displacement immunoassay for fatty acid-binding protein

In standard displacement flow immunoassays the analyte in the sample creates an active dissociation of labelled antigens (or antigen homologues) from an antigen binding site of an immobilized antibody, after which the labelled substance is measured downstream. Such systems have been described for molecules up to 1 kDa. In this study, we demonstrate displacement in a flow system for the detection of a small protein, cytoplasmic heart-type fatty acid-binding protein (15 kDa), a plasma marker for myocardial injury. The displacement system uses an inverse set-up: enzyme labelled monoclonal antibodies are associated to immobilized antigen, and are displaced by analyte in the sample. The system permits detection of both physiological (2-12 microg l(-1)) and pathological concentrations (12-2000 microg l(-1)) of fatty acid-binding protein in an on-line flow system.