A novel DNAzyme-based paper sensor for the simple visual detection of RNase H activity

Here, we report a novel DNAzyme-based paper sensor to detect RNase H activity. The paper sensor was constructed by dropping a DNA/RNA duplex containing a guanine-rich DNA strand whose bases are complementary to the RNA strand, onto a Hybond™-N+ membrane. In the presence of RNase H, the RNA strand of the G-DNA/Cp-RNA duplex was hydrolyzed, which released G-DNA sequences to form a G-quadruplex/hemin HRP-mimetic DNAzyme after hemin was added to the membrane surface. Then, the formed DNAzymes catalyzed the oxidation of the TMB substrate, which changed the color of the paper sensor, thus realizing RNase H detection. Under the optimized conditions, a linear concentration range of 5∼ 60 U/mL with a limit of detection of 1.2 U/mL for RNase H was obtained. The paper sensor was also used to detect RNase H in complex biosamples containing cell lysates.