Colorimetric Hg2+ Detection with a Label-free and Fully DNA-structured Sensor Assembly Incorporating G-quadruplex Halves

A sensitive and fully DNA-structured ion sensor was built by integrating polyT sequences for highly selective Hg2+ recognitions and two flanking G-quadruplex halves for allosteric signal transductions. The construction of this sensor was very easy that allowed a cost-effective detection of Hg2+ with a limit of detection of 4.5 nM, which was lower than the 10 nM toxic level for drinkable water as regulated by the US's EPA. The strategy employed for the construction of this sensor may be further extended to other sensors through a rational structural fusion between re-engineered aptameric and enzymic DNA sequences.