Minimizing Nonspecific Adsorption in Protein Biosensors that Utilize Electrochemical Impedance Spectroscopy

Peanut protein Ara h 1, a common food allergen, has been previously detected at antibody-coated Au electrodes using electrochemical impedance spectroscopy (EIS) in ideal solutions, free from interfering species. Here, peanut protein Ara h 1 is detected by EIS at antibody-coated Au electrodes in canned soup that is filtered, diluted, and spiked with peanut protein Ara h 1. In this system, the combined strategy of sample dilution and blocking of unreacted surface sites on the Au electrode with bovine serum albumin is sufficient to dramatically reduce nonspecific adsorption. This is demonstrated by a quantitative comparison of the impedance change at two Au electrodes, one coated with the antibody to peanut protein Ara h 1 and the other coated with the antibody to cockroach protein Bla g 1. These results suggest that nonspecific adsorption does not in general limit the utility of biosensors based on EIS.