▎ 摘　　要

A new fluorometric method is delineated for the detection of RNase H activity by combining DNAzyme with reduced graphene oxide (rGO). In the absence of RNase H, the fluorescence of FAM-labeled probe is quenched due to the strong adsorption on the rGO. The presence of RNase H can release the active DNAzyme from the DNA-RNA chimeric strand. This triggers the cleavage of the signal probe at the rA site with the help of the cofactor Mg2+. The recycle cleavage can directly result in the amplifiedsignal emitted bytheFAM-labeled short fragment. The method allows the activity of RNase H to be detected in a linear range of 0.01 to 5UmL(-1). The detection limit of 0.018UmL(-1) is calculated by the principle of three-time standard deviation over the blank signal. Then, RNase H-targeting natural compounds were screenedfor their inhibitory action. Among the investigated compounds, five were screened as RNase H inhibitors in a concentration-dependent manner, and 4 compounds were identified as activators. Finally, the method was reliably used for discriminating the difference of RNase H activity in human serum. It is found that RNase H activity was upregulated in patients with hepatitis C virus infection.