Title: Electrophoretic study to detect the biomolecules using graphene-based field effect transistor

Abstract

Graphene based sensor devices have been investigated significantly and results of different chemicals decorated on a graphene sheet were identified by the transfer characteristics. The GFET based device was fabricated by the mechanical exfoliation method with an inbuilt reference electrode acting as an electrolyte gate electrode. Devices show good transfer characteristics, which depend on the surface morphology of the material and substrate. During fabrication of the device, the substrate morphology was disturbed in appropriately by the contamination of the surface. In the present study, monolayer Graphene Field Effect Transistor (GFET) was driven with hydrophobic Hexamethyl Disilazane (HMDS) layer. Fabrication of GFET device on the hydrophobic substrate enhances the effective ambipolar behaviour. The fabricated devices were used for direct adsorption of single- and double-stranded DNA. Detection of disease-related gene expression by DNA hybridization is one of the useful diagnostic methods. In this study a monolayer graphene field effect transistor (GFET) was used for the detection of a particular single-stranded DNA (target DNA). The VDirac was shifted to the negative direction in the probe DNA immobilization. In recent cases of cancer therapy, such as DNA based therapies, messenger RNA (mRNA) is also used as alternatives. mRNA has a good capability to classify cancer subtypes. The device can support mRNA detection and provides the best platform for cancer detection. Furthermore, the monolayer GFET is driven by an inbuilt top-gate for detecting the pH of the contacting buffer solution. The fabricated devices are also used to detect the protein samples decorated on the channel surface. Detection of protein is the most important diagnostic method for immune regulation and metabolism. The GFET device detects the effect of hydroxide ions on a graphene surface. The sensitivity of the device was estimated the device performance. Fabrication of this kind of compact GFET device with inbuilt gate enables low-cost, real-time sensitive amperometric sensors, which enhances the effective sensing and user-friendly in the platform of biosensing applications.