Patel Sandeep A, Cozzuol Matteo, Hales Joel M, Richards Chris I, Sartin Matthew, Hsiang Jung-Cheng, Vosch Tom, Perry Joseph W, Dickson Robert M
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400.
J Phys Chem C Nanomater Interfaces. 2009 Nov 26;113(47):20264-20270. doi: 10.1021/jp9079537.
Various single-standed DNA-encapsulated Ag nanoclusters (nanodots) exhibit strong, discrete fluorescence with solvent polarity-dependent absorption and emission throughout the visible and near-IR. All species examined, regardless of their excitation and emission energies, show similar µs single-molecule blinking dynamics and near IR transient absorptions. The polarity dependence, µsec blinking, and indistinguishable µsec-decaying transient absorption spectra for multiple nanodots suggest a common charge transfer-based mechanism that gives rise to nanodot fluorescence intermittency. Photoinduced charge transfer that is common to all nanodot emitters is proposed to occur from the Ag cluster into the nearby DNA bases to yield a long-lived charge-separated trap state that results in blinking on the single molecule level.
各种单链DNA包裹的银纳米簇（纳米点）在整个可见光和近红外区域表现出强烈的、离散的荧光，其吸收和发射依赖于溶剂极性。所有检测的物种，无论其激发和发射能量如何，都表现出类似的微秒级单分子闪烁动力学和近红外瞬态吸收。多个纳米点的极性依赖性、微秒级闪烁以及难以区分的微秒级衰减瞬态吸收光谱表明，存在一种基于电荷转移的共同机制，导致纳米点荧光间歇性。据推测，所有纳米点发射体共有的光诱导电荷转移发生在银簇到附近的DNA碱基中，产生一个长寿命的电荷分离陷阱态，导致单分子水平上的闪烁。
