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Effects of K+ and Na+ ions on the fluorescence of colloidal CdSe/CdS and CdSe/ZnS quantum dots
KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
KTH, School of Biotechnology (BIO), Theoretical Chemistry (closed 20110512).
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2011 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, Vol. 155, no 2, 823-830 p.Article in journal (Refereed) Published
Abstract [en]

In this work we studied the effects of K+ and Na+ ions on fluorescence properties of the colloidal quantum dots (QDs). It was found that the fluorescence intensity was enhanced when low concentration of ions was introduced to QD solutions, while it became weakened when ion concentrations reached their physiological levels in many bio environments. Such fluorescence changes can be attributed to interactions between QD surface ligands and ions as well as the Coulomb potential of ions that displaces the wave functions of the electron and hole confined inside the QD. These results are important for understanding the influence of different biological environments, such as extracellular and intracellular compartments, on optical properties of colloidal QDs.

Place, publisher, year, edition, pages
2011. Vol. 155, no 2, 823-830 p.
Keyword [en]
Colloidal quantum dots (QDs), Fluorescence properties of QDs, Electron and hole confinements in QDs, Effects of K+ and Na+ ions
National Category
Chemical Sciences
URN: urn:nbn:se:kth:diva-33396DOI: 10.1016/j.snb.2011.01.055ISI: 000291774100055ScopusID: 2-s2.0-79957805848OAI: diva2:415029
QC 20110705Available from: 2011-05-05 Created: 2011-05-05 Last updated: 2011-07-05Bibliographically approved
In thesis
1. Quantum dot biomarkers for tracking endothelial progenitor cells and activated endothelium
Open this publication in new window or tab >>Quantum dot biomarkers for tracking endothelial progenitor cells and activated endothelium
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The development of new visualization techniques is essential in the field of bioimaging to gain deeper knowledge about various medical and biological events at the cellular and molecular levels. Quantum dots (QDs) are semiconductor nanocrystals which are opening new perspectives in biotechnology due to their powerful optical properties and high stability.  Utilization of QDs instead of commonly used organic dyes in labeling techniques adds several advantages, such as longer signal observation time of the biological samples; convenient multicolor labeling; deep tissue and organ tracking. Furthermore, more information can be obtained about the environment where QDs are located by characterizing the optical behavior of the QDs.

In this thesis work carboxyl coated QDs were used to label endothelial progenitor cells (EPCs). EPCs play an important role in cardiovascular diseases and the repair of the damaged endothelium, therefore an efficient in vivo tracking method is essential to understand the therapeutic potential of these cells. Our findings show an effective, cytoplasmic labeling of EPCs. Cell viability assay shows that QDs are not toxic to the cells in the concentration and incubation time tested in the study and QDs does not change the cell functions.

Furthermore commercially available QDs were functionalized with VCAM-1 binding peptide (VCAM-1BP) to specifically detect activated endothelial cells and activated endothelial wall in the aorta. Endothelial wall of the arteries are activated with VCAM-1 in the early stages of atherosclerosis, therefore early detection of this chronic disease may be performed with VCAM-1BP functionalized QDs. We found that VCAM-1BP functionalized QDs were able to detect the activated endothelium specifically.

The optical behavior of the QDs in different conditions and bio-systems were also characterized. It was found that several circumstances like different coating ligands can modify the fluorescence of the QDs. We observed that QD fluorescence intensity changes with different concentrations of Na+ and K+. We also found that significant blue-shift in QD peak emission occurs when QDs are internalized by cells and when functionalized QDs interact with cell surface molecule.

This thesis work provides efficient labeling techniques for cells and tissues with QDs and important knowledge about the optical behavior of QDs in bio-systems. These results give further perspectives to the future application of QD biomarkers as tracking agent and optical sensors for the different environmental changes in bio-systems.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. 52 p.
Trita-BIO-Report, ISSN 1654-2312
quantum dots, bioimaging, endothelium, adult stem cells, confocal microscopy
National Category
Biochemistry and Molecular Biology
urn:nbn:se:kth:diva-33295 (URN)978-91-7415-929-5 (ISBN)
Public defence
2011-05-25, FA 51, Roslagstullsbacken, AlbaNova, Stockholm, 14:00 (English)
QC 20110505Available from: 2011-05-05 Created: 2011-05-02 Last updated: 2011-05-12Bibliographically approved

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Molnár, MátyásFu, Ying
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