Field-effect transistor for biosensing applications using a graphene channel with amine-rich coatings

Since graphene has a unique band structure with the valence and conduction bands touching each other at a single point called the Dirac point, this makes it extremely sensitive to the surroundings such as doping, external electric field, mechanical deformation, etc. Hence, it is very desirable for sensing applications. However, its surface inertness poses significant drawbacks. Therefore, it is necessary to treat the graphene surface to bind biomolecules. In this paper, we report the use of amine-functionalized graphene by plasma polymerization to detect the presence of biomolecules in graphene channel based on a liquid-gate field-effect transistor (LG-GFET). Taking streptavidin and biotin as an example, the binding interactions of streptavidin–biotin complexes are detected by monitoring the shift of the Dirac point. By varying the streptavidin concentrations from 0.1 nM to 1000 nM, we found that our LG-GFET achieves detection capabilities as low as 0.1 nM. Our approach can be applied for the detection of biological molecules with low detection limit, high sensitivity, and stability. • Graphene surface functionalized with amino groups by plasma polymerization • Fluorescent images demonstrate the conjugation of streptavidin to biotin • Dirac point shifts with streptavidin concentration at detection level as low as 0.1nM