The optical properties of the silver clusters and their applications in the conformational studies of human telomeric DNA

Abstract

In this study, we investigated the optical properties of the silver nanoclusters (AgNCs) labeled on the 22 bases human telomeric DNA sequences (d[AG3(T2AG3)3], Hum 22AG). The steady state spectra indicate that the formation of the G-quadruplex structure will quench the fluorescence of the AgNCs. In contrast to the AgNCs labeled on the Hum 22AG, the absorption and emission spectra of the AgNCs labeled on the duplex structure are shifted due to the change of local environment and the cluster-base interactions. Moreover, the AgNCs also represent slower spectral relaxation dynamics in the duplex structure, and the result is associated with the stronger hydrogen bond networking and the higher structural rigidity of the duplex. By comparing fluorescence anisotropy dynamics of the Hum 22AG probed by different fluorescence probes, we found that labelling the AgNCs on the DNA would suppress the wobbling motion of the chromophore. The fluorescence anisotropy study also showed an increase in the structural rigidity of the duplex structure.