The construction and characterization of an amperometric immunosensor for the thyroid hormone...

A novel amperometric immunosensor, based on graphite paste (graphite powder and paraffin oil), has been constructed for the assay of L-T4. The graphite paste is impregnated with mouse monoclonal anti-(+)-3,3',5,5'-tetraiodo-L-thyronine (anti-L-T4). The immunosensor can be reliably used for the assay of L-T4 in thyroid and in drugs, using chronoamperometry technique, at ppt up to ppb concentration levels. The potential used for L-T4 assay was +450 mV vs. Ag/AgCl electrode. The surface of the immunosensor can be regenerated by simply polishing, obtaining fresh immunocomposite ready to be used in a new assay.