Silver Clusters as Both Chromophoric Reporters and DNA Ligands
详细信息 查看全文
- 作者：Jeffrey T. Petty ; Banabihari Giri ; Ian C. Miller ; David A. Nicholson ; Orlin O. Sergev ; Taylor M. Banks ; Sandra P. Story
- 刊名：Analytical Chemistry
- 出版年：2013
- 出版时间：February 19, 2013
- 年：2013
- 卷：85
- 期：4
- 页码：2183-2190
- 全文大小：367K
- 年卷期：v.85,no.4(February 19, 2013)
- ISSN：1520-6882
文摘
Molecular silver clusters conjugated with DNA act as analyte sensors. Our studies evaluate a type of cluster-laden DNA strand whose structure and silver stoichiometry change with hybridization. The sensor strand integrates two functions: the 3鈥?region binds target DNA strands through base recognition while the 5鈥?sequence C3AC3AC3TC3A favors formation of a near-infrared absorbing and emitting cluster. This precursor form exclusively harbors an 11 silver atom cluster that absorbs at 400 nm and that condenses its single-stranded host. The 3鈥?recognition site associates with a complementary target strand, thereby effecting a 330 nm red-shift in cluster absorption and a background-limited recovery of cluster emission at 790 nm. One factor underlying these changes is sensor unfolding and aggregation. Variations in salt and oligonucleotide concentrations control cluster development by influencing DNA association. Structural studies using fluorescence anisotropy, fluorescence correlation spectroscopy, and size exclusion chromatography show that the sensor-cluster conjugate opens and subsequently dimerizes with hybridization. A second factor contributing to the spectral and photophysical changes is cluster transformation. Empirical silver stoichiometries are preserved through hybridization, so hybridized, dimeric near-infrared conjugates host twice the amount of silver in relation to their violet absorbing predecessors. These DNA structure and net silver stoichiometry alterations provide insight into how DNA-silver conjugates recognize analytes.