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Fluorescence intensity and intermittency as tools for following dopamine bioconjugate processing in living cells.

Khatchadourian R, Bachir A, Clarke SJ, Heyes CD, Wiseman PW, Nadeau JL - J. Biomed. Biotechnol. (2007)

Bottom Line: CdSe/ZnS quantum dots (QDs) conjugated to biomolecules that quench their fluorescence, particularly dopamine, have particular spectral properties that allow determination of the number of conjugates per particle, namely, photoenhancement and photobleaching.In this work, we quantify these properties on a single-particle and ensemble basis in order to evaluate their usefulness as a tool for indicating QD uptake, breakdown, and processing in living cells.This creates a general framework for the use of fluorescence quenching and intermittency to better understand nanoparticle-cell interactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, McGill University, 3775 Rue University, 316 Lyman Duff Medical Building, Montréal, Canada.

ABSTRACT
CdSe/ZnS quantum dots (QDs) conjugated to biomolecules that quench their fluorescence, particularly dopamine, have particular spectral properties that allow determination of the number of conjugates per particle, namely, photoenhancement and photobleaching. In this work, we quantify these properties on a single-particle and ensemble basis in order to evaluate their usefulness as a tool for indicating QD uptake, breakdown, and processing in living cells. This creates a general framework for the use of fluorescence quenching and intermittency to better understand nanoparticle-cell interactions.

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Related in: MedlinePlus

Subcellular differences in QD-dopamine fluorescence. (a) Image under DAPI filter of cells labeled with QD-dopamine (and with SYTO red to show nuclei). The green regions (540–580 nm emission) show QD fluorescence but no dopamine fluorescence. The blue areas (460–500 nm emission) show dopamine fluorescence and no initial QD fluorescence; QD fluorescence appears after UV illumination.  Double-labeling experiments identified the green areas as lysosomes (not shown) or as regions exterior to the cell. (b) Closeup of a single cell from panel A showing blue spots (square) and green spots (circle). (c) Time course of QD peak fluorescence under UV illumination (QD filter) for a blue region (squares) and a green region (circles).
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fig5: Subcellular differences in QD-dopamine fluorescence. (a) Image under DAPI filter of cells labeled with QD-dopamine (and with SYTO red to show nuclei). The green regions (540–580 nm emission) show QD fluorescence but no dopamine fluorescence. The blue areas (460–500 nm emission) show dopamine fluorescence and no initial QD fluorescence; QD fluorescence appears after UV illumination. Double-labeling experiments identified the green areas as lysosomes (not shown) or as regions exterior to the cell. (b) Closeup of a single cell from panel A showing blue spots (square) and green spots (circle). (c) Time course of QD peak fluorescence under UV illumination (QD filter) for a blue region (squares) and a green region (circles).

Mentions: Observation of the blue QD-dopamine fluorescence confirmedwhat was suggested by the time-course spectra.QDs outside the cells showed no blue emission, confirming the absence ofdopamine, whereas those in the cytoplasm and mitochondria showed visible 460 nmemission (see Figure 5).


Fluorescence intensity and intermittency as tools for following dopamine bioconjugate processing in living cells.

Khatchadourian R, Bachir A, Clarke SJ, Heyes CD, Wiseman PW, Nadeau JL - J. Biomed. Biotechnol. (2007)

Subcellular differences in QD-dopamine fluorescence. (a) Image under DAPI filter of cells labeled with QD-dopamine (and with SYTO red to show nuclei). The green regions (540–580 nm emission) show QD fluorescence but no dopamine fluorescence. The blue areas (460–500 nm emission) show dopamine fluorescence and no initial QD fluorescence; QD fluorescence appears after UV illumination.  Double-labeling experiments identified the green areas as lysosomes (not shown) or as regions exterior to the cell. (b) Closeup of a single cell from panel A showing blue spots (square) and green spots (circle). (c) Time course of QD peak fluorescence under UV illumination (QD filter) for a blue region (squares) and a green region (circles).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2279208&req=5

fig5: Subcellular differences in QD-dopamine fluorescence. (a) Image under DAPI filter of cells labeled with QD-dopamine (and with SYTO red to show nuclei). The green regions (540–580 nm emission) show QD fluorescence but no dopamine fluorescence. The blue areas (460–500 nm emission) show dopamine fluorescence and no initial QD fluorescence; QD fluorescence appears after UV illumination. Double-labeling experiments identified the green areas as lysosomes (not shown) or as regions exterior to the cell. (b) Closeup of a single cell from panel A showing blue spots (square) and green spots (circle). (c) Time course of QD peak fluorescence under UV illumination (QD filter) for a blue region (squares) and a green region (circles).
Mentions: Observation of the blue QD-dopamine fluorescence confirmedwhat was suggested by the time-course spectra.QDs outside the cells showed no blue emission, confirming the absence ofdopamine, whereas those in the cytoplasm and mitochondria showed visible 460 nmemission (see Figure 5).

Bottom Line: CdSe/ZnS quantum dots (QDs) conjugated to biomolecules that quench their fluorescence, particularly dopamine, have particular spectral properties that allow determination of the number of conjugates per particle, namely, photoenhancement and photobleaching.In this work, we quantify these properties on a single-particle and ensemble basis in order to evaluate their usefulness as a tool for indicating QD uptake, breakdown, and processing in living cells.This creates a general framework for the use of fluorescence quenching and intermittency to better understand nanoparticle-cell interactions.

View Article: PubMed Central - PubMed

Affiliation: Department of Biomedical Engineering, McGill University, 3775 Rue University, 316 Lyman Duff Medical Building, Montréal, Canada.

ABSTRACT
CdSe/ZnS quantum dots (QDs) conjugated to biomolecules that quench their fluorescence, particularly dopamine, have particular spectral properties that allow determination of the number of conjugates per particle, namely, photoenhancement and photobleaching. In this work, we quantify these properties on a single-particle and ensemble basis in order to evaluate their usefulness as a tool for indicating QD uptake, breakdown, and processing in living cells. This creates a general framework for the use of fluorescence quenching and intermittency to better understand nanoparticle-cell interactions.

Show MeSH
Related in: MedlinePlus