Ultrasensitive Label-free MiRNA Sensing Based on a Flexible Graphene Field-Effect Transistor without Functionalization

Abstract

A flexible graphene field-effect transistor (Gr-FET) biosensor for ultrasensitive and specific detection of miRNA without labeling and functionalization is reported. The flexible biosensor presents robust performance even after multiple cycles of bending to a cylinder with an 8 mm radius. A DNA probe is designed with partial segment complementary to target miRNA, and immobilized on the graphene surface though π–π stacking interaction. After capture of target miRNA, a Dirac point shift in Gr-FET is induced, which shows a linear relationship with the target miRNA concentration on a semi-log scale. The Gr-FET-based biosensor finishes miRNA detection in 20 min, and is able to achieve a miRNA detection limit as low as 10 fM without any functionalization and labeling. The interaction processes of DNA-graphene and DNA-miRNA are confirmed through surface-enhanced Raman scattering technology. The proposed biosensor will have prospective applications in wearable electronics for health monitoring and disease diagnosis.