Label-Free Sensors Based on Graphene Field-Effect Transistors for the Detection of Human Chorionic Gonadotropin Cancer Risk Biomarker

• Published in: Diagnostics (Basel) Vol. 8; no. 1; p. 5
• Main Authors: Haslam, Carrie, Damiati, Samar, Whitley, Toby, Davey, Paul, Ifeachor, Emmanuel, Awan, Shakil A
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 08.01.2018; MDPI
• Subjects: Alzheimer’s disease; antibodies; blood biomarkers; cancer; cardiovascular; dementia; diagnosis; electrical detection; electrochemical biosensors; graphene; neurodegenerative disorders; proteins; Sensors; blood biomarkers; electrochemical biosensors; Alzheimer’s disease; electrical detection; proteins; dementia; diagnosis; antibodies; cancer; cardiovascular; neurodegenerative disorders; graphene
• ISSN: 2075-4418; 2075-4418
• DOI: 10.3390/diagnostics8010005

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