The assays relied on the target-induced synthesis of Mg2+-dependent DNAzyme for catalyzing the cleavage of Fc-DNA from paper, which had been proved by using microRNA recognition probe for miR-21, a biomarker for cardiovascular disease and cancer, a phosphorylated hairpin probe for alkaline phosphatase enzyme, and a DNA aptamer for CEA, respectively (Figure 6). The gene discussed is CEACAM5; the disease is cancer.