A novel graphene oxide-based fluorescence assay for RNA endonuclease activity of mammalian Argonaute2 protein

A novel graphene oxide (GO)-based amplified fluorescence assay for RNA endonuclease activity of mammalian Argonaute2 (Ago2) was developed. Owing to the extraordinarily high quenching efficiency of GO, the probe labeled with a fluorophore carboxyfluorescein exhibits minimal background fluorescence, while strong fluorescence intensity is observed with the addition of Ago2–miRNA complex due to the scission of the target mRNA sequences and the release of FAM-linked oligonucleotide fragments. Furthermore, Ago2–miRNA complex may be released to initiate another cycle of cleavage. The newly designed simple and cost-effective method exhibits high sensitivity with a detection limit of 1.7 nM (3σ) for Ago2 endonuclease activity.