Graphene solution-gated field effect transistor DNA sensor fabricated by liquid exfoliation and double glutaraldehyde cross-linking

Abstract

Graphene based solution-gated field effect transistors (G-SgFETs) have been extensively investigated as potential biosensors for various analytes. Liquid exfoliated graphene (LEG) is a recently developed economic and efficient carbon material, in comparison with graphene materials produced by other methods like Hummers, mechanical exfoliation and epitaxy. However, bio-sensitive and LEG based SgFETs (bioLEG-SgFETs) have not been demonstrated because of the deficiency in oxygen containing groups on LEG nano-sheets which are believed to be able to graft bio-sensing probes. Here, we describe a method for fabricating bioLEG-SgFETs and demonstrate their bio-application in single-strand DNA (ssDNA) detection, for the first time. The as-prepared LEG supernatant, deposited and functionalized films are thoroughly characterized by scanning electron microscopy, atom force microscopy, Raman and X-ray photoelectron spectroscopy. Furthermore, the feasibility of the proposed method is testified by the typical ambipolar transferring features possessed by G-SgFETs, as well as the ionic screening effect exhibited by the bio-modified G-SgFETs. BioLEG-SgFETs' performance acting as a sensor is evaluated by the detection of DNA hybridization, as proof-of-concept, which include target complementary ssDNA (csDNA), mismatched and half-matched ssDNA. The limit-of-detection for csDNA is about 10 fM. Accordingly, LEG would be a promising alternative for the traditional graphene materials used in G-SgFETs.