A single quantum dot-based nanosensor for the signal-on detection of DNA methyltransferase.

We develop a single quantum dot (QD)-based nanosensor for the signal-on detection of DNA methyltransferase (MTase). By integration of single-molecule counting with the QD-based fluorescence resonance energy transfer (FRET), the proposed nanosensor can sensitively detect DNA MTase with a detection limit of as low as 0.002 U mL-1 , and it can be further applied for inhibitor screening and accurate detection of DNA MTase in complex biological samples.