A new graphene oxide enhanced fluorescence anisotropy strategy for microRNA detection

MicroRNAs (miRNA) are a class of small non-coding RNA molecules, whose abnormal expression or perturbation is associated with cancer and other diseases. Thus, identification of perturbed miRNAs using sensitive detection techniques is crucial. In view of this, we developed a novel graphene oxide (GO) amplified fluorescence anisotropy (FA) strategy for the detection of miRNA-21. In this method, a GO/capture DNA (cDNA)/Linker DNA/probe DNA (pDNA) (DNA-GO) composite probe was constructed, wherein target catalized singal cyclic amplification strategy was used to assist GO to amplify the FA signal. After the formation of DNA-GO composite probe, the FA of the fluorophore on Linker DNA was enhanced by GO because of the increased volume and mass. With the addition of miRNA-21, pDNA was released from Linker DNA through toehold-mediated strand exchange reaction. Fuel DNA then hybridized with Linker DNA to form a double-stranded DNA (dsDNA), which was detached from the surface of GO, and FA of the fluorophore on Linker DNA was reduced. Additionally, miRNA-21 was released after the formation of dsDNA, which triggered the next cycle, resulting in further reduction of FA value. By monitoring the reduced FA values, miRNA-21 could be detected in the range of 10–330 nmol/L and the limit of detection (LOD) was 1.09 nmol/L.