Luminescence sensitization of Tb 3+ -DNA complexes by Ag .

Terbium ions (Tb3+) with unique photophysical properties have been utilized to develop biosensors with low background and high sensitivity. In this study, the Ag+-sensitized luminescence of Tb3+-DNA complexes was uncovered. The luminescence of Tb3+-DNA complexes could be enhanced by more than 30 times in the presence of Ag+, when Tb3+ was bound with poly(G) and poly(T) whereas not with other homopolymers. This research confirmed that the sensitization resulted from the interaction of Ag+ with certain bases involved in DNA, not just with the reported certain G-quadruplex sequence. The coordination of Ag+ to guanine and thymine bases was expected to increase their rigidities, form Tb3+-DNA-Ag+ ternary structures, and thus enhance energy transfer from guanine and thymine to Tb3+. These findings benefit the development of sensitive luminescence probes for various nucleic acids-related targets.