Brightness calibrates particle size in single particle fluorescence imaging

Zhihe Liu, Zezhou Sun, Weihua Di, Weiping Qin, Zhen Yuan, Changfeng Wu

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


This Letter provides a novel approach to quantify the particle sizes of highly bright semiconductor polymer dots (Pdots) for single-particle imaging and photo bleaching studies. A quadratic dependence of single-particle brightness on particle size was determined by single-particle fluorescence imaging and intensity statistics. In terms of the same imaging conditions, the particle diameter can be quantified by comparing the individual brightness intensity with associated calibration curve. Based on this sizing method, photo bleaching trajectories and overall photon counts emitted by single particles were analyzed. It is found that photo bleaching rate constants of different sized Pdots are not strongly dependent on particle diameter except the sparsely occurring fluorescence blinking in certain dim particles and the rapid photo bleaching component in some bright particles. The overall photon counts increase with increasing particle diameter. However, those larger than 30 nm deviate away from the increasing tendency. These results reveal the significance of selecting appropriate Pdots (≤30 nm) for single-particle imaging and tracking applications.

Original languageEnglish
Pages (from-to)1242-1245
Number of pages4
JournalOptics Letters
Issue number7
StatePublished - 2015
Externally publishedYes


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