Correlation of photobleaching, oxidation and metal induced fluorescence quenching of DNA-templated silver nanoclustersElectronic supplementary information (ESI) available: Additional photostability, DNA exposure to light, effect of EDTA and AgNC drying. See DOI: 10.1039/c3nr33421j

Few-atom noble metal nanoclusters have attracted a lot of interest due to their potential applications in biosensor development, imaging and catalysis. DNA-templated silver nanoclusters (AgNCs) are of particular interest as different emission colors can be obtained by changing the DNA sequence. A po...

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Main Authors: Morishita, Kiyoshi, MacLean, James L, Liu, Biwu, Jiang, Hui, Liu, Juewen
Format: Article
Language:English
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Summary:Few-atom noble metal nanoclusters have attracted a lot of interest due to their potential applications in biosensor development, imaging and catalysis. DNA-templated silver nanoclusters (AgNCs) are of particular interest as different emission colors can be obtained by changing the DNA sequence. A popular analytical application is fluorescence quenching by Hg 2+ , where d 10 -d 10 metallophilic interaction has often been proposed for associating Hg 2+ with nanoclusters. However, it cannot explain the lack of response to other d 10 ions such as Zn 2+ and Cd 2+ . In our effort to elucidate the quenching mechanism, we studied a total of eight AgNCs prepared by different hairpin DNA sequences; they showed different sensitivity to Hg 2+ , and DNA with a larger cytosine loop size produced more sensitive AgNCs. In all the cases, samples strongly quenched by Hg 2+ were also more easily photobleached. Light of shorter wavelengths bleached AgNCs more potently, and photobleached samples can be recovered by NaBH 4 . Strong fluorescence quenching was also observed with high redox potential metal ions such as Ag + , Au 3+ , Cu 2+ and Hg 2+ , but not with low redox potential ions. Such metal induced quenching cannot be recovered by NaBH 4 . Electronic absorption and mass spectrometry studies offered further insights into the oxidation reaction. Our results correlate many important experimental observations and will fuel the further growth of this field. DNA templated fluorescent silver nanoclusters show a correlation between light and Hg 2+ sensitivity; both are attributed to oxidation.
ISSN:2040-3364
2040-3372
DOI:10.1039/c3nr33421j