Rational fabrication of a DNA walking nanomachine on graphene oxide surface for fluorescent bioassay

DNA nanomachines, a delicate type of molecular machines, have been a research hotspot in biotechnology and materials. Here a two-dimensional (2D) DNA walking nanomachine with high working efficiency and low cost was easily assembled by using graphene oxide (GO) as the working platform for precisely fluorescent bioassay through the binding of target hepatitis B virus DNA (HBV-DNA) and the driving force of Exonuclease III (Exo III). The presence of HBV-DNA made continuous Exo III digestion of the FAM-modified DNA (FAM-DNA) in double-strand DNA (dsDNA) part in a burnt-bridge mechanism to output a "one-to-more" amplified signal. Accordingly, a 2D DNA walking nanomachine with simple operation and high cost-performance ratio was constructed. The walking speed of nanomachine was found to be regulated by loading DNA density on single sheet of GO. Furthermore, this nanomachine had low background since the dual energy transfer including fluorescence resonance energy transfer (FRET) from FAM to BHQ1 and the long-range resonance energy transfer (LrRET) from FAM to GO, making the biosensing applications highly promising.