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Mechanisms of fluorescence decays of colloidal CdSe-CdS/ZnS quantum dots unraveled by time-resolved fluorescence measurement
KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Experimental Biomolecular Physics.
KTH, School of Engineering Sciences (SCI), Applied Physics, Cell Physics.ORCID iD: 0000-0003-0578-4003
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2015 (English)In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 17, no 41, 27588-27595 p.Article in journal (Refereed) Published
Abstract [en]

By narrowing the detection bandpass and increasing the signal-to-noise ratio in measuring the time-resolved fluorescence decay spectrum of colloidal CdSe-CdS/ZnS quantum dots (QDs), we show that directly after the photoexcitation, the fluorescence decay spectrum is characterized by a single exponential decay, which represents the energy relaxation of the photogenerated exciton from its initial high-energy state to the ground exciton state. The fluorescence decay spectrum of long decay time is in the form of beta/t(2), where beta is the radiative recombination time of the ground-state exciton and t is the decay time. Our findings provide us with a direct and quantitative link between fluorescence decay measurement data and fundamental photophysics of QD exciton, thereby leading to a novel way of applying colloidal QDs to study microscopic, physical and chemical processes in many fields including biomedicine.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2015. Vol. 17, no 41, 27588-27595 p.
Keyword [en]
Phonon Bottleneck, Cdte Nanocrystals, Energy-Transfer, Emission, Electron, Blinking, Relaxation, Nanoparticles, Microscopy, Lifetimes
National Category
Subatomic Physics Other Physics Topics Atom and Molecular Physics and Optics
URN: urn:nbn:se:kth:diva-176997DOI: 10.1039/c5cp03109eISI: 000363193800038PubMedID: 26426293ScopusID: 2-s2.0-84944339303OAI: diva2:871694
Swedish Research Council, 621-2011-4381Knut and Alice Wallenberg Foundation, KAW 2011.0218

QC 20151116

Available from: 2015-11-16 Created: 2015-11-13 Last updated: 2016-09-02Bibliographically approved
In thesis
1. Fluorescence Properties of Quantum Dots and Their Utilization in Bioimaging
Open this publication in new window or tab >>Fluorescence Properties of Quantum Dots and Their Utilization in Bioimaging
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Quantum dots (QDs), especially colloidal semiconductor QDs, possess properties including high quantum yields, narrow fluorescence spectra, broad absorption and excellent photostability, making them extremely powerful in bioimaging. In this thesis, we studied the fluorescence properties of QDs and attempted multiple ways to boost applications of QDs in bioimaging field.

By time-correlated single photon counting (TCSPC) measurement, we quantitatively interpreted the fluorescence mechanism of colloidal semiconductor QDs.

To enhance QD fluorescence, we used a porous alumina membrane as a photonic crystal structure to modulate QD fluorescence.

We studied the acid dissociation of 3-mercaptopropionic acid (MPA) coated QDs mainly through electrophoretic mobility of 3-MPA coated CdSe QDs and successfully demonstrated the impact of pH change and Ca2+ ions.

Blinking phenomena of both CdSe-CdS/ZnS core-shell QDs and 3C-SiC nanocrystals (NCs) were studied. A general model on blinking characteristics relates the on-state distribution to CdSe QD surface conditions. The energy relaxation pathway of fluorescence of 3C-SiC NCs was found independent of surface states.

To examine QD effect on ciliated cells, we conducted a 70-day long experiment on the bioelectric and morphological response of human airway epithelial Calu-3 cells with periodic deposition of 3-MPA coated QDs and found the cytotoxicity of QDs was found very low.

In a brief summary, our study of QD could benefit in bioimaging and biosensing. Especially, super-resolution fluorescent bioimaging, such as, stochastic optical reconstruction microscopy (STORM) and photo-activated localization microscopy (PALM), may benefit from the modulation of the QD blinking in this study. And fluorescence lifetime imaging (FLIM) microscopy could take advantage of lifetime modulation based on our QD lifetime study.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2016. 77 p.
TRITA-FYS, ISSN 0280-316X ; 2016:54
Fluorescence, Microscopy, Bioimaging, Nanomaterial, cytotoxicity, mechanism
National Category
Research subject
Biological Physics
urn:nbn:se:kth:diva-191985 (URN)78-91-7729-074-2 (ISBN)
External cooperation:
Public defence
2016-09-29, Seminar room Earth, Science for life laboratory, Tomtebodavägen 23A, Solna, 13:00 (English)

QC 20160905

Available from: 2016-09-07 Created: 2016-09-02 Last updated: 2016-09-07Bibliographically approved

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