Graphene Biosensor-Based Field-Effect Biosensing to Detect Protein-Protein Interactions

Protein-protein interactions, PPIs, are critical in regulating most biological processes.

To detect PPIs using field-effect biosensing, begin with a graphene field-effect transistor chip. The chip comprises a carboxyl-functionalized graphene surface as the semiconductive channel between the source and drain electrodes.

Incubate the chip with a fresh solution of carbodiimide and N-hydroxysulfosuccinimide, sulfo-NHS, in a zwitterionic buffer. This buffer creates a suitable pH, enabling carbodiimide and sulfo-NHS to activate the chip's functionalized carboxyl groups, forming amine-reactive esters.

Add the target protein solution. The primary amines react with the amine-reactive esters, immobilizing the proteins on the chip through amide bond formation. Add amine-containing quenching solution to block unbound amine-reactive esters, preventing non-specific binding.

Insert the chip in the electronic reader and calibrate it with a buffer. The reader applies a constant voltage between the electrodes. The resulting electrical current flow between the electrodes in the analyte-unbound condition is measured.

Add the lowest analyte concentration. The interaction between analyte proteins and th