期刊
ANALYTICAL CHEMISTRY
卷 85, 期 4, 页码 2183-2190出版社
AMER CHEMICAL SOC
DOI: 10.1021/ac303531y
关键词
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资金
- National Science Foundation [CBET-0853692]
- Henry Dreyfus Teacher-Scholar Awards Program
- Regional NSF-REU Site in Chemistry at Furman University
- Furman Advantage program
- USE Award from the Howard Hughes Medical Institute
- Henry Keith and Ellen Hard Townes Professorship
- Div Of Chem, Bioeng, Env, & Transp Sys
- Directorate For Engineering [0853692] Funding Source: National Science Foundation
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' region binds target DNA strands through base recognition while the 5' sequence C(3)AC(3)AC(3)TC(3)A favors formation of a near-infrared absorbing and emitting cluster. This precursor form exclusively harbors an similar to 11 silver atom cluster that absorbs at 400 nm and that condenses its single-stranded host. The 3' 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.
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