Improving sensor response using reduced graphene oxide film transistor biosensor by controlling the adsorption of pyrene as an anchor molecule

Reduced graphene oxide (rGO) films functionalized with linker molecules that bind specific antibodies to the surface of their films are useful for biosensors based on field-effect transistors. Controlling the density of linker molecules on the rGO channel surface is a crucial issue for improving the sensor structure with the desired sensitivity and stability. In this study, ultraviolet–visible (UV–vis) absorption spectroscopy was utilized for the evaluation of the density of linker molecules adsorbed on the rGO and GO surfaces. We revealed that the density of adsorbed linker molecules on the rGO surface is dominated by oxygen-containing groups slightly remaining on the surfaces, rather than the restoration of the π-conjugated system in the graphitic structure of rGO films. We demonstrate that the difference in the density of adsorbed linker molecules on the rGO films significantly affects the sensitivity of sensor responses.