Label-free dual assay of DNA sequences and potassium ions using an aptamer probe and a molecular light switch complex

A homogeneous assay is reported using Ru(phen)(2)(dppz)(2+) and a K(+)-binding aptamer for the selective and sensitive detection of a target oligonucleotide and potassium ions, based on reduction in fluorescence emission according to the formation of the G-quadruplex structure from the aptamer in the presence of K(+).