Anti-Biofouling Effect of Nanoporous Gold Electrode on Nonspecific Signal Reduction for Electrochemical Biosensors

Abstract

Noise signals based on nonspecific adsorptions of interfering species (biofouling) should be reduced in electrochemical biosensors to increase the signal-to-noise ratio. Here, we demonstrate the effect of the structure of nanoporous gold (np-Au) electrodes on anti-biofouling in electrochemical biosensors. A np-Au electrode is fabricated by a gold–silver alloy corrosion process. The pore size of the np-Au electrode is controlled within 10–50 nm by adjusting the time of corrosion of silver. The np-Au electrode, the pore size of which is slightly larger (15–30 nm) than the size of proteins such as human serum albumin (HSA), notably shows the suppression of the nonspecific adsorption of HSA on its surface in cyclic voltammetry (CV), resulting in the anti-biofouling effect. In particular, the peak current in CV with the np-Au electrode is maintained at about 80% even for a long-term incubation of 60 min after the addition of human serum and plasma as well as HSA, whereas that with the bare gold electrode is reduced to about 25%–60%. The anti-biofouling effect of the np-Au electrode is discussed on the basis of the balance between its pore size and protein size, including the electrostatic repulsion with proteins.