2012 年 37 巻 2 号 p. 255-258
The interdigitated electrode (IDE), that has a series of parallel micro-band electrodes with alternating micro-bands connected together, was utilized in electrochemical impedance spectroscopy (EIS) to build non-labeled human immunoglobulin A (IgA) immunosensor. Anti-human IgA was employed as a molecular receptor being covalently immobilized on the IDE through a self-assembled monolayer. EIS results exhibited that the adsorption induced by the antigen-antibody reaction between IgA and anti-IgA made an increase in resistance of the interfacial electron transfer (Rct). A linear relationship between the ΔRct and the logarithm of IgA concentration was confirmed for the IgA concentration range of 0.1 - 100 ng/mL. No modulation of Rct was detected by immersing in the solution of other proteins such as human immunoglobulin G, which indicates a high selectivity of this sensor for IgA. The surface images of sensor before and after the IgA binding were observed by atomic force microscopy.
