Luminescence sensitization of Tb³⁺-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.