An on-chip FRET biosensor built on a graphene-biomolecular-interface

Abstract

We developed a biomolecular interface on the surface of graphene (or graphene oxide) to detect biologically important proteins such as cancer markers. Here, graphene behaves as an efficient acceptor for fluorescence resonance energy transfer (FRET) over the entire visible wavelength region. Graphene works simultaneously as a strong adsorbate for single-stranded DNAs (ssDNAs) such as aptamers by a π-π interaction in the sp² domain. In our system, the graphene surface is modified with a pyrene-aptamer-dye probe. The segments work as a linker to the graphene surface, a selective protein recognition part, and a fluorescence detection tag. The system allows us to perform molecular detection on a solid surface, which constitutes a powerful tool for realizing an on-chip sensor. Using the on-chip sensor, detection of the target protein is possible simply by adding a sample smaller than 1 µL to a sensor chip and is complete in about a minute. Here we review our recent achievements using the on-chip biosensor, which include the simultaneous detection of multiple target molecules on a single chip, the molecular design of a probe for enhancing the sensitivity, and a quantitative comparison of the sensing performance using graphene and graphene oxide platforms.