Direct correlation between potentiometric and impedance biosensing of antibody-antigen interactions using an integrated system

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Supplementary Information
Date
2017-08-16
Authors
Tsai, Meng-Yen
Creedon, Niamh
Brightbill, Eleanor
Pavlidis, Spyridon
Brown, Billyde
Gray, Darren W.
Shields, Niall
Sayers, Rí­ona
Mooney, Mark H.
O'Riordan, Alan
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AIP Publishing
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Abstract
A fully integrated system that combines extended gate field-effect transistor (EGFET)-based potentiometric biosensors and electrochemical impedance spectroscopy (EIS)-based biosensors has been demonstrated. This integrated configuration enables the sequential measurement of the same immunological binding event on the same sensing surface and consequently sheds light on the fundamental origins of sensing signals produced by FET and EIS biosensors, as well as the correlation between the two. Detection of both the bovine serum albumin (BSA)/anti-BSA model system in buffer solution and bovine parainfluenza antibodies in complex blood plasma samples was demonstrated using the integrated biosensors. Comparison of the EGFET and EIS sensor responses reveals similar dynamic ranges, while equivalent circuit modeling of the EIS response shows that the commonly reported total impedance change (DZtotal) is dominated by the change in charge transfer resistance (Rct) rather than surface capacitance (Csurface). Using electrochemical kinetics and the Butler-Volmer equation, we unveil that the surface potential and charge transfer resistance, measured by potentiometric and impedance biosensors, respectively, are, in fact, intrinsically linked. This observation suggests that there is no significant gain in using the FET/EIS integrated system and leads to the demonstration that low-cost EGFET biosensors are sufficient as a detection tool to resolve the charge information of biomolecules for practical sensing applications.
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Keywords
Biochemistry , Biosensors , Capacitance , Electrochemical impedance spectroscopy , Electrochemical sensors , Molecular biophysics , Proteins
Citation
Tsai, M.-Y., Creedon, N., Brightbill, E., Pavlidis, S., Brown, B., Gray, D. W., Shields, N., Sayers, R., Mooney, M. H., O'Riordan, A. and Vogel, E. M. (2017) 'Direct correlation between potentiometric and impedance biosensing of antibody-antigen interactions using an integrated system', Applied Physics Letters, 111(7), 73701(5pp). doi:10.1063/1.4986190
Copyright
© 2017, the Authors. Reproduced from Tsai, M.-Y., Creedon, N., Brightbill, E., Pavlidis, S., Brown, B., Gray, D. W., Shields, N., Sayers, R., Mooney, M. H., O'Riordan, A. and Vogel, E. M. (2017) 'Direct correlation between potentiometric and impedance biosensing of antibody-antigen interactions using an integrated system', Applied Physics Letters, 111(7), 73701(5pp). doi:10.1063/1.4986190, with the permission of AIP Publishing.