Blinking and nonradiant dark fraction of water-soluble quantum dots in aqueous solution.
Blinking and nonradiant dark fraction of water-soluble quantum dots in aqueous solution.
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DOI：
10.1073/pnas.0506523102
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发表时间：
2005-10
影响因子：
11.1
通讯作者：
Jie Yao;D. Larson;Harshad D. Vishwasrao;W. Zipfel;W. Webb
中科院分区：
文献类型：
--
作者：
Jie Yao;D. Larson;Harshad D. Vishwasrao;W. Zipfel;W. Webb
水溶性量子点（qdots）利用其明亮、易激发的荧光和高光稳定性，现已应用于生命科学研究。尽管在所有可用量子点中出现的频繁的不稳定闪烁和大量的暗（从未辐射）部分可能会干扰许多应用，但生物环境中单个粒子的这些特性尚未得到充分评估。通过用有机染料标记qdot -链霉亲和素，我们可以区分单个的暗点和亮点，并观察到qdots在水溶液中自由扩散时的闪烁事件。采用共聚焦荧光符合分析（CFCA）和双光子互相关荧光相关光谱（FCS）测定亮分数。观察到的各种制备的亮度分数与系综量子产率（QYs）成正比，但单个量子点的本征亮度在具有不同QYs但相同发射波长的样品中是恒定的。在FCS期间，将qdots的照明停留时间增加10倍，并没有改变明显黑暗的qdots的比例，但确实增加了闪烁qdots的检测比例，这表明黑暗人口不是由毫秒闪烁引起的。将CFCA与稀琼脂糖凝胶中定位的量子点阵列的宽视场成像相结合，在时间上测量了5个数量级的量子点闪烁：大约0.001-100秒。本研究描述了量子点在生物相关环境中的光物理病理特征，而不是粘附在电介质表面，并描述了用于研究各种生物应用纳米粒子的方法。
Water-soluble quantum dots (qdots) are now being used in life sciences research to take advantage of their bright, easily excited fluorescence and high photostability. Although the frequent erratic blinking and substantial dark (never radiant) fractions that occur in all available qdots may interfere with many applications, these properties of individual particles in biological environments had not been fully evaluated. By labeling Qdot-streptavidin with organic dyes, we were able to distinguish individual dark and bright qdots and to observe blinking events as qdots freely diffused in aqueous solution. Bright fractions were measured by confocal fluorescence coincidence analysis (CFCA) and two-photon cross-correlation fluorescence correlation spectroscopy (FCS). The observed bright fractions of various preparations were proportional to the ensemble quantum yields (QYs), but the intrinsic brightness of individual qdots was found to be constant across samples with different QYs but the same emission wavelengths. Increasing qdots' illuminated dwell time by 10-fold during FCS did not change the fraction of apparently dark qdots but did increase the detected fraction of blinking qdots, suggesting that the dark population does not arise from millisecond blinking. Combining CFCA with wide-field imaging of arrays of qdots localized in dilute agarose gel, the blinking of qdots was measured across five orders of magnitude in time: approximately 0.001-100 s. This research characterizes photophysical pathologies of qdots in biologically relevant environments rather than adhered on dielectric surfaces and describes methods that are useful for studying various bioapplicable nanoparticles.