Observation of the interaction between avidin and iminobiotin using a graphene FET on a SiC substrate

Fine chemical changes were electrically detected by functionalized epitaxial graphene field-effect transistors (GFET) on SiC substrates, which were expected to have the intrinsic sensing characteristics of a single-crystal graphene film. An iminobiotin (IB)-modified GFET was fabricated to measure the interaction between avidin and IB. IB interacts strongly with avidin in a solution at pH 9, while the interaction becomes weak at a lower pH. The electrical characteristics shifted with increasing concentration of avidin at pH 7 and pH 9, and could be fitted by the adsorption isotherm. However, almost constant electrical characteristics were observed at pH 4. These pH dependences clearly showed that a modified GFET with an epitaxial graphene film on a SiC substrate can act as an environmental sensor for small chemical reactions.