Detection of DNA and Poly-L-Lysine using CVD Graphene-channel FET Biosensors

TL;DR

This paper demonstrates a CVD graphene-channel FET biosensor capable of detecting DNA and poly-l-lysine with high sensitivity by measuring shifts in Dirac voltage, offering a reusable and easy-to-fabricate platform for charged biomolecule detection.

Contribution

It introduces a clean transfer method for graphene biosensors and shows their effectiveness in detecting charged biomolecules through conductance changes.

Findings

Detection limits of 8 pM for DNA and 11 pM for poly-l-lysine.

Polarity of Dirac voltage shift depends on the charged molecule.

Sensors are reusable and easy to fabricate.

Abstract

A graphene channel field-effect biosensor is demonstrated for detecting the binding of double-stranded DNA and poly-l-lysine. Sensors consist of CVD graphene transferred using a clean, etchant-free transfer method. The presence of DNA and poly-l-lysine are detected by the conductance change of the graphene transistor. A readily measured shift in the Dirac Voltage (the voltage at which the graphenes resistance peaks) is observed after the graphene channel is exposed to solutions containing DNA or poly-l-lysine. The Dirac voltage shift is attributed to the binding/unbinding of charged molecules on the graphene surface. The polarity of the response changes to positive direction with poly-l-lysine and negative direction with DNA. This response results in detection limits of 8 pM for 48.5 kbp DNA and 11 pM for poly-l-lysine. The biosensors are easy to fabricate, reusable and are promising as sensors of a wide variety of charged biomolecules