We have developed a graphene-biomolecular-interface to detect biologically important proteins such as cancer markers. 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 section for selective protein recognition, and a fluorescence detection tag. Here, graphene behaves simultaneously as both an efficient acceptor for fluorescence resonance energy transfer (FRET) over the entire visible region and as a strong adsorbate for single-stranded DNAs (ssDNA), such as aptamers, via a π-π interaction in the sp<sup>2</sup> domain. The system allows us to perform molecular detection on a solid surface, which is advantageous for realizing an on-chip sensor. This feature also enables us to extend the biosensing platform from two-dimensional plane to three-dimensional hollow space by building the biomolecular-interface on a flexible surface such as layered polymer films. A demonstration of protein detection in a micro-polymer-cylinder by covering its inner surface with aptamer-modified graphene is ongoing.<br/>A merit of using an on-chip sensor is that it realizes a parallel analysis system such as array sensors. This allows us to undertake a quantitative comparison of different samples by forming a multichannel configuration and/or a micropattern with the probes. We fabricated a 2×3 linear-array aptasensor by using thrombin and prostate specific antigen (PSA), which were labeled with red and green fluorescent dyes, respectively. Fluorescence was only observed in the areas where the correct aptamer-target pair had been formed. The simultaneous detection of multiple target molecules on a single chip was demonstrated. Moreover, detection of the target protein is possible simply by adding a sample smaller than 1 μL to a sensor chip and is completed in about a minute.

Graphene FRET aptasensor built on a solid support

253rd National Meeting (2017)

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