1 Chemical Vapour Deposition Graphene Field - Effect 2 Transistors for Detection of Human Chorionic 3 Gonadotropin Cancer Risk Biomarker 4

We report on the development of chemical vapour deposition (CVD) based graphene 11 field effect transistor (GFET) immunosensors for the sensitive detection of Human Chorionic 12 Gonadotropin (hCG), a glycoprotein risk biomarker of certain cancers. The GFET sensors were 13 fabricated on Si/SiO2 substrate using photolithography with evaporated chromium and sputtered 14 gold contacts. GFET channels were functionalized with a linker molecule to immobile anti-hCG 15 antibody on the surface of graphene. Binding reaction of the antibody with varying concentration 16 levels of hCG antigen demonstrated the limit of detection of the GFET sensors to be below 1 pg/mL 17 using four-probe electrical measurements. We also show annealing can significantly improve the 18 carrier transport properties of GFETs and shift the Dirac point (Fermi level) with reduced p-doping 19 in back-gated measurements. The developed GFET biosensors are generic and could find 20 applications in a broad range of medical diagnostics in addition to cancer, such as 21 neurodegenerative (Alzheimer’s, Parkinson’s and Lewy body) and cardiovascular disorders. 22 23