The integration of gold nanoparticles with semi-conductive oligomer layer for development of capacitive immunosensor

A new strategy for constructing the capacitance immunosensor was developed based on gold nanoparticles, which were employed as the platform to immobilize immunospecies. Gold nanoparticles were fixed on the gold electrode, on which the oligomer layer of o-aminobenzenthiol was pre-formed via electrochemical polymerization. An interesting immunospecies was loaded on gold nanoparticles to complete the fabrication of capacitance immunosensor. The changes in morphology of the gold electrode during the experiments were revealed by atomic force microscopy (AFM). The properties of the gold electrode were investigated by cyclic voltammetry, in the presence of an electro-active species as indictor. Also, potentiostatic pulse technique was used in order to evidence the changes of electrode capacitance. The feasibility of the proposed capacitive immunosensor was evaluated for a non-competitive heterogeneous immunoassay of transferrin. The assay covers a relatively large dynamic range of 0.125-100 ng/ml transferrin with a detection limit of 80 pg/ml and a relative high signal-to-noise ratio.