Immunoassay of C-reactive protein by hot electron-induced electrochemiluminescence at polystyrene-carbon black composite electrodes

Aromatic Tb(III) chelates can be detected down to subnanomolar concentrations at polystyrene-carbon black composite electrodes on the basis of hot electron-induced electrochemiluminescence, and used as electrochemiluminescent labels in bioaffinity assays. The excitation mechanism is based on chemiluminescent reactions that are initiated by the field emission/tunnel emission of hot electrons from the composite electrode. The composition and the properties of the novel composite electrodes were studied in detail. Hot electron-induced electrochemiluminescence intensities obtainable with the present composite electrodes are comparable to the previously used metal/insulator-type electrodes without exhibiting considerable long-lived solid state electroluminescence background emission, unlike e.g. oxide-coated silicon and aluminum electrodes.