As a highly conserved damage repair protein, RNase H can specifically hydrolyze RNA in DNA-RNA chimeric strands. DNAzyme, a synthetic single-stranded DNA consisting of binding and catalytic sites, can cleave RNA in the presence of cofactors. In this study, we establish a highly sensitive RNase H assay assisted with DNAzyme's cleavage property. A DNA-RNA chimeric strand, which contains DNAzyme sequences, is used as the hydrolysis substrate of RNase H. The RNase H hydrolysis of the chimeric substrate results in the release of DNAzyme. Subsegment DNAzyme digest, a molecular beacon, causes a "turn...