Direct potentiometric immunoelectrodes

Summary

Antibodies immobilized on the surface of titanium wires may be used as direct potentiometric immunoelectrodes. In order to make full use of the potentially high selectivity and sensitivity of such sensors, careful investigations on the optimization of immobilizing proteins on such surfaces have been carried out. The final process uses a polystyrene coating on titanium wires with subsequent immobilization of proteins by azo coupling. The best suited buffer solution for IgG coating was found to be carbonate buffer pH 9.18 and a second coating with BSA could be shown to close yet active sites of titanium or polystyrene, thus preventing unspecific binding of any small molecules/antigens. This latter finding will be especially important with immunoelectrodes, where such small molecules would replace buffer ions at those sites, which would most probably yield high potential changes covering completely the desired measuring effects from the binding of a small antigen to an immobilized antibody.