An electrochemiluminescence assay for sensitive detection of methyltransferase activity in different cancer cells by hybridization chain reaction coupled with a G-quadruplex/hemin DNAzyme biosensing strategy.

In this work, a highly sensitive electrochemiluminescence (ECL) assay was fabricated for the detection of human DNA (cytosine-5)-methyltransferase1 (DNMT1) activity in cancer cells. The ECL assay coupled hybridization chain reaction with a G-quadruplex/hemin DNAzyme biosensing strategy. The ECL intensity changes (ΔI) allowed detection of DNMT1 activity down to 0.09 U mL-1 , and ΔI was proportional to the logarithm of the activity of DNMT1 within the range of 1.0 to 30.0 U mL-1 in buffer solution. It also showed high sensitivity to DNMT1 activity in A549 cells, with a detection limit of about 2 cells. This ECL assay provides a promising platform for profiling of the mutational cells of tumors and shows a great potential for application to DNA methylation-related clinical diagnostics.