Use of fluorescent DNA-templated gold/silver nanoclusters for the detection of sulfide ions.
We have developed a one-pot approach to prepare fluorescent DNA-templated gold/silver nanoclusters (DNA-Au/Ag NCs) from Au(3+), Ag(+), and DNA (5'-CCCTTAATCCCC-3') in the presence of NaBH(4) in order to detect sulfide (S(2-)) ions on the basis of fluorescence quenching. The as-prepared DNA-Au/Ag NCs have been characterized by UV-vis absorption, fluorescence, circular dichroism, X-ray photoelectron spectroscopy, and electrospray ionization-mass spectrometry measurements. Relative to DNA-Ag NCs, DNA-Au/Ag NCs are much more stable in high ionic strength media (e.g., 200 mM NaCl). The quantum yield of the as-prepared DNA-Au/Ag NCs is 4.5%. We have demonstrated that the fluorescence of DNA-Au/Ag NCs is quenched by S(2-) ions through the interaction between sulfide ions and gold/silver atoms/ions, a result which leads to changes in the conformation of the templated DNA from packed hairpin to random coil structures. These changes in fluorescence intensity allow sensitive detection of S(2-) ions at concentrations as low as 0.83 nM. To minimize interference from I(-) ions for the detection of S(2-) ions using the DNA-Au/Ag NCs, the addition of sodium peroxydisulfate to the solution is essential. We have validated the practicality of this probe for the detection of S(2-) ions in hot spring and seawater samples, demonstrating its advantages of simplicity, sensitivity, selectivity, and low cost.
Department of Chemistry, National Taiwan University, Taipei, Taiwan.
Wei-Yu
WY
Chen
Guo-Yu
GY
Lan
Huan-Tsung
HT
Chang
D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry; D005618:Fresh Water / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013440:Sulfides / Q000032:analysis*
D005456:Fluorescent Dyes; D007477:Ions; D013440:Sulfides; D012834:Silver; D006046:Gold; D004247:DNA