Rapid detection of methyltransferases utilizing dumbbell DNA-templated copper nanoparticles

DNA methylation, as an epigenetic event of DNA modification, plays important roles in genetic disorders and diseases, such as cancer, and increasing evidence has shown that DNA methyltransferase (MTase) can be utilized as a biomarker for genetic diseases. In the present study, a smart detection system for DNA methyltransferase was established based on a target-protection principle. In the presence of MTase, as the sensor, dumbbell template DNA (DT DNA) was methylated and resisted endonuclease and exonuclease digestion. Thus, fluorescence was able to be rapidly detected after restoring Cu2+ in the detection system above. However, if the template DNA was digested into nucleotides without the protection of MTase, the following step of fluorescence copper nanoparticle (CuNP) synthesis would fail because it is template dependent. Therefore, under optimal conditions, a detection limit of approximately 1.6968 × 10−4 U/μL MTase activity was achieved. In addition, this real sample assay shows promise for potential application in complex environments. Furthermore, the proposed MTase-detection system can be utilized to screen inhibitors or drugs for MTase.