Blinking and nonradiant dark fraction of water-soluble quantum dots in aqueous solution

被引:191
作者
Yao, J
Larson, DR
Vishwasrao, HD
Zipfel, WR
Webb, WW
机构
[1] Cornell Univ, Sch Appl & Engn Phys, Ithaca, NY 14853 USA
[2] Cornell Univ, Field Biochem Mol & Cell Biol, Ithaca, NY 14853 USA
[3] Yeshiva Univ Albert Einstein Coll Med, Dept Anat & Struct Biol, Bronx, NY 10461 USA
[4] Columbia Univ, Ctr Neurol & Behav, New York, NY 10027 USA
关键词
nanoparticles; fluorescence; correlation; spectroscopy; imaging;
D O I
10.1073/pnas.0506523102
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
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: approximate to 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.
引用
收藏
页码:14284 / 14289
页数:6
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