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

Carrie Haslam,Paul Davey,Samar Damiati,Shakil A Awan,Toby Whitley,Emmanuel Ifeachor

doi:10.3390/diagnostics8010005

Carrie Haslam, Paul Davey + Show 4 more

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https://doi.org/10.3390/diagnostics8010005

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Journal: Diagnostics	Publication Date: Jan 8, 2018
Citations: 48	License type: CC BY 4.0

Affiliation: University of Plymouth, King Abdulaziz University

Abstract

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.

Highlights

Since the discovery and isolation of graphene from graphite in 2004, the two-dimensional material has shown potential to revolutionise many technological areas owing to its remarkable electrical, optical, mechanical and thermal properties [1,2,3]
Our data presented in this study has demonstrated that chemical vapour deposition (CVD) graphene field-effect transistor (FET) can sensitively detect Human Chorionic Gonadotropin (hCG) antigen with approximately three to four orders of magnitude lower concentration level compared to commercially available sensors
We have demonstrated the use of CVD graphene FETs on Si/SiO2 substrate as sensitive label-free immunosensors for the proof-of-concept detection of hCG antigen, with a limit of detection (LoD) below ~1 pg/mL

Summary

Introduction

Since the discovery and isolation of graphene from graphite in 2004, the two-dimensional material has shown potential to revolutionise many technological areas owing to its remarkable electrical, optical, mechanical and thermal properties [1,2,3]. Its chemical stability, low electrical noise, significant surface-to-volume ratio, biocompatibility and field-effect make graphene potentially an ideal platform for a variety of biosensing applications [4]. The extraordinary surface-to-volume ratio of graphene facilitates a high density of disease specific capture molecules or antibodies to be chemically immobilised onto its surface via covalent or non-covalent functionalisation techniques. A key benefit of the latter is that the electrical transport properties of graphene are not degraded as the mobility and carrier properties are maintained. This can enhance the sensitivity of the biosensor and thereby improve its limit of detection (LoD). A number of biosensor techniques are being explored to detect the presence of a given biomarker, such as electrical, optical, Diagnostics 2018, 8, 5; doi:10.3390/diagnostics8010005 www.mdpi.com/journal/diagnostics

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