Functionalisation of Graphene Sensor Surfaces for the Specific Detection of Biomarkers

We report on a controllable and specific functionalisation route for graphene field-effect transistors (GFETs) for the recognition of small physiologically active molecules. Key element is the noncovalent functionalisation of the graphene surface with perylene bisimide (PBI) molecules directly on the growth substrate. This Functional Layer Transfer enables the homogeneous self-assembly of PBI molecules on graphene, onto which antibodies are subsequently immobilised. The sensor surface was characterised by atomic force microscopy, Raman spectroscopy and electrical measurements, showing superior performance over conventional functionalisation after transfer. Specific sensing of small molecules was realised by monitoring the electrical property changes of functionalised GFET devices upon the application of methamphetamine and cortisol. The concentration dependent electrical response of our sensors was determined down to a concentration of 300 ng ml(-1) for methamphetamine.

Automated summary

We present a controllable and specific functionalisation approach for graphene field-effect transistors (GFETs) in order to detect small physiologically active molecules. The key step involves the noncovalent functionalisation of graphene with perylene bisimide (PBI) molecules directly on the growth substrate. This method allows for the homogeneous self-assembly of PBI molecules on graphene, followed by the immobilization of antibodies. The functionalised GFET devices showed excellent performance in terms of atomic force microscopy, Raman spectroscopy, and electrical measurements compared to conventional functionalisation methods. Specific sensing of small molecules such as methamphetamine and cortisol was achieved by monitoring the electrical changes of the functionalised GFET devices. The sensors were able to detect methamphetamine down to a concentration of 300 ng ml(-1).