Ag K-Edge EXAFS Analysis of DNA-Templated Fluorescent Silver Nanoclusters: Insight into the Structural Origins of Emission Tuning by DNA Sequence Variations

Abstract

DNA-templated silver nanoclusters are promising biological fluorescence probes due to their useful fluorescence properties, including tunability of emission wavelength through DNA template sequence variations. Ag K-edge EXAFS analysis of DNA-templated silver nanoclusters has been used to obtain insight into silver nanocluster bonding, size, and structural correlations to fluorescence. The results indicate the presence of small silver nanoclusters (<30 silver atoms) containing Ag–Ag bonds and Ag–N/O ligations to DNA. The DNA sequence used leads to differences in silver–DNA ligation as well as silver nanocluster size. The results support a model in which cooperative effects of both Ag–DNA ligation and variations in cluster size lead to the tuning of the fluorescence emission of DNA-templated silver nanoclusters