Scheme 1. Schematic illustration of cytosine-5 methylation-directed construction of a AuNP-based nanosensor for simultaneous detection of multiple DNA MTases (i.e., M.SssI and M.CviPI MTases) at the single-molecule level. This assay consists of three steps: (1) DNA MTase-catalyzed cytosine-5 methylation for inducing the cleavage of hairpin substrates by GlaI, (2) RNase HII-mediated recycling cleavage of signal probes for liberating Cy5 and Cy3 molecules from the AuNP nanostructures, and (3) simultaneous detection of Cy5 and Cy3 molecules at the single-molecule level.
