Graphene FRET Aptasensor

We report on a new protein sensor built on pristine graphene. Graphene grown by chemical vapor deposition and supported on a SiO 2 surface was modified with a sequence consisting of pyrene, DNA aptamer, and dye. Here, an aptamer is a nucleic acid having a specific base sequence that recognizes and forms a complex with a target molecule such as a protein. In our protein sensing system, the recognition of a target protein triggers the fluorescence of a dye tethered on the graphene surface. This is based on the effective fluorescence quenching property of graphene via fluorescence resonance energy transfer (FRET). We first demonstrate that the graphene FRET aptasensor yields fluorescence when there is a target protein in the sample using prostate specific antigen (PSA, a cancer marker) as the target. We confirm that the fluorescence intensities vary depending on the PSA concentrations. We also discuss the selectivity and limit of detection using a microchannel configuration built on a graphene FRET aptasensor. A similar aptasensor has been intensively studied using graphene oxide (GO) dispersed in aqueous media, but has been little studied on a solid support. By preparing the graphene and GO FRET aptasensor on the same substrate, we show quantitatively that the graphene sensor yields brighter fluorescence than the GO aptasensor. We also demonstrate the response of the graphene FRET aptasensor under sample flow conditions.