Biosensors Based on Electrochemical Impedance Spectroscopy
Electrochemical impedance spectroscopy (EIS) has long been used to understand the nature of an electrochemical interface, including whether or not an oxide/passive film is present, and to quantify the kinetics of redox reactions. Our research group has been studying the development of biosensors that employ EIS as a method to quantify antibody-antigen or ligand-receptor binding at an immobilized protein film. Impedance results at an electrochemical interface are often presented as Nyquist plots, with Zreal plotted along the x-axis, and Zimag plotted along the y-axis, with the different probe frequencies spread along this plot.The first figure below is a 3D image of peanut protein Ara h 1, a common food allergen. The second figure is a Nyquist plot of the impedance response at an Au electrode coated with the mouse monoclonal antibody to Ara h 1. The semicircle diameter corresponds approximately to the charge transfer resistance (Rct) in this system, which gradually increases with increasing concentration of peanut protein.
Trimeric form of peanut protein Ara h 1
[Ara h 1] = 0, 0.02, 0.04, 0.08, 0.16 and 0.24 mg/ml
Here are some publications from our research group in the field of EIS biosensors:
M. Pali, J.E. Garvey, B.C. Small and I.I. Suni, “Impedance Detection of Fish Hormones by Electrochemical Impedance Spectroscopy and Quartz Crystal Microbalance,” in press in Sens. Biosens. Res.
C.S. Bever, Z. Majkova, R. Radhakrishnan, I.I. Suni, M. McCoy, Y.R. Wang, J. Dechant,S. Geeand B.D. Hammock,“Development and Utilization of Camelid VHH Antibodies from Alpaca for BDE-47 Detection,” Anal. Chem. 86, 7875 (2014).
J. Wang, L.A. Luck and I.I. Suni, "Immobilization of the Glucose/galactose Receptor (GGR) Protein onto an Au Electrode through a Genetically Engineered Cysteine Residue," Electrochem. Solid-State Lett. 10, J33 (2007).
J. Wang, K.A. Carmon, L.A. Luck and I.I. Suni, "Electrochemical Impedance Biosensor for Glucose Detection Utilizing a Periplasmic E. coli Receptor Protein," Electrochem. Solid-state Lett. 8, H61 (2005).