Petty Jeffrey T, Fan Chaoyang, Story Sandra P, Sengupta Bidisha, Iyer Ashlee St John, Prudowsky Zachary, Dickson Robert M
Department of Chemistry, Furman University, Greenville, SC 29613.
J Phys Chem Lett. 2010 Sep 2;1(17):2524-2529. doi: 10.1021/jz100817z.
Photostability, inherent fluorescence brightness, and optical modulation of fluorescence are key attributes distinguishing silver nanoclusters as fluorophores. DNA plays a central role both by protecting the clusters in aqueous environments and by directing their formation. Herein, we characterize a new near infrared-emitting cluster with excitation and emission maxima at 750 and 810 nm, respectively that is stabilized within C(3)AC(3)AC(3)TC(3)A. Following chromatographic resolution of the near infrared species, a stoichiometry of 10 Ag/oligonucleotide was determined. Combined with excellent photostability, the cluster's 30% fluorescence quantum yield and 180,000 M(-1)cm(-1) extinction coefficient give it a fluorescence brightness that significantly improves on that of the organic dye Cy7. Fluorescence correlation analysis shows an optically accessible dark state that can be directly depopulated with longer wavelength co-illumination. The coupled increase in total fluorescence demonstrates that enhanced sensitivity can be realized through Synchronously Amplified Fluorescence Image Recovery (SAFIRe), which further differentiates this new fluorophore.
光稳定性、固有荧光亮度以及荧光的光学调制是区分银纳米簇作为荧光团的关键属性。DNA通过在水性环境中保护簇以及指导其形成发挥核心作用。在此，我们表征了一种新的近红外发射簇，其激发和发射最大值分别在750和810nm，该簇在C(3)AC(3)AC(3)TC(3)A内稳定。在对近红外物种进行色谱分离后，确定了10个Ag/寡核苷酸的化学计量比。结合出色的光稳定性，该簇30%的荧光量子产率和180,000 M(-1)cm(-1)的消光系数赋予其荧光亮度，显著优于有机染料Cy7。荧光相关性分析显示存在一个可通过更长波长的共照射直接消除的光学可及暗态。总荧光的耦合增加表明，通过同步放大荧光图像恢复（SAFIRe）可以实现增强的灵敏度，这进一步区分了这种新的荧光团。
