Highly Sensitive Simultaneous Detection of Lead(II) and Barium(II) with G-Quadruplex DNA in α-Hemolysin Nanopore

Both Pb2+ and Ba2+ can bind with high affinity to some specific DNA sequences, inducing the formation of unimolecular G-quadruplex structures. Translocation of a DNA probe containing such sequences through an α-hemolysin nanopore in the presence of Pb2+ or Ba2+ would result in much prolonged DNA translocation events. Quantification of these events can reveal the concentrations of Pb2+ or Ba2+ at as low as 0.8 nM. Besides, Pb2+ and Ba2+ in the solution can be simultaneously detected and individually identified. Furthermore, the probe is highly selective for Pb2+ and Ba2+ detection without interference from other metal ions. This sensing strategy can be extended to many other analytes which can bind to DNA molecules with high affinity.