Abstract
Biorecognition is a central event in biological processes in the living systems that is also widely exploited in technological and health applications. We demonstrate that the Electrolyte Gated Organic Field Effect Transistor (EGOFET) is an ultrasensitive and specific device that allows us to quantitatively assess the thermodynamics of biomolecular recognition between a human antibody and its antigen, namely, the inflammatory cytokine TNFα at the solid/liquid interface. The EGOFET biosensor exhibits a superexponential response at TNFα concentration below 1 nM with a minimum detection level of 100 pM. The sensitivity of the device depends on the analyte concentration, reaching a maximum in the range of clinically relevant TNFα concentrations when the EGOFET is operated in the subthreshold regime. At concentrations greater than 1 nM the response scales linearly with the concentration. The sensitivity and the dynamic range are both modulated by the gate voltage. These results are explained by establishing the correlation between the sensitivity and the density of states (DOS) of the organic semiconductor. Then, the superexponential response arises from the energy-dependence of the tail of the DOS of the HOMO level. From the gate voltage-dependent response, we extract the binding constant, as well as the changes of the surface charge and the effective capacitance accompanying biorecognition at the electrode surface. Finally, we demonstrate the detection of TNFα in human-plasma derived samples as an example for point-of-care application.
Highlights
Biorecognition is a central phenomenon in living matter that relies on complex patterns of labile, non-covalent intermolecular interactions
We demonstrate that the Electrolyte Gated Field Effect Transistor (EGOFET) is an ultrasensitive and specific device that allows us to quantitatively assess the thermodynamics of biomolecular recognition between a human antibody and its antigen, viz. the inflammatory cytokine TNFα, at solid/liquid interface
EGOFET biosensors comprising immobilization of a specific receptor either on the OSC11 or on the gate (G) electrode12–14 were demonstrated with sensitvity comparable to stateof-the-art techniques such as enzyme-linked immunosorbent assay (ELISA) or surface plasmon resonance (SPR)
Summary
Original Publication: Marcello Berto, Stefano Casalini, Michele Di Lauro, Simone L. Bortolotti and Fabio Biscarini, Biorecognition in Organic Field Effect Transistors Biosensors: The Role of the Density of States of the Organic Semiconductor, ANALYTICAL CHEMISTRY, 2016. Biorecognition in organic field effect transistors biosensors: the role of the density of states of the organic semiconductor Marcello Bertoa, Stefano Casalinia+, Michele Di Lauro,a Simone L. Marassob,c, Matteo Cocuzzab,c, Denis Perroned, Marcello Pintia, Andrea Cossarizzae, Candido F. +Present address: Institut de Ciéncia de Materials de Barcelona (ICMAB-CSIC), 08193 Bellaterra, Spain
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