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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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Probability histograms for (a) on-times and (a) off-times durations with (red) and without (blue) dopamine conjugated to the QD surface. A strong effect of dopamine in both on-times and off-times durations is evident. The addition of dopamine reduces the probability of observing long on-times and increases the probability of observing long off-times.
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fig7: Probability histograms for (a) on-times and (a) off-times durations with (red) and without (blue) dopamine conjugated to the QD surface. A strong effect of dopamine in both on-times and off-times durations is evident. The addition of dopamine reduces the probability of observing long on-times and increases the probability of observing long off-times.

Mentions: Westudied the effect of conjugating dopamine to QDs on their blinking statistics.The probability distributions of on times, P(on), and off times, P(off), for QDs with and without conjugateddopamine are shown in Figures 7(a) and 7(b), respectively, as measured byextracting fluorescence time traces, such as shown in Figure 6(b), setting athreshold and calculating on and off times. Approximately 500 QDs were analyzedfrom 5 sets of movies, taken at 50-millisecond resolution for 100 seconds. Exceptfor the dopamine, the QDs and the experimental conditions were identical.Clearly, under these conditions, the conjugation of dopamine to the QD reducedthe on times and increasedthe off times.


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)

Probability histograms for (a) on-times and (a) off-times durations with (red) and without (blue) dopamine conjugated to the QD surface. A strong effect of dopamine in both on-times and off-times durations is evident. The addition of dopamine reduces the probability of observing long on-times and increases the probability of observing long off-times.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig7: Probability histograms for (a) on-times and (a) off-times durations with (red) and without (blue) dopamine conjugated to the QD surface. A strong effect of dopamine in both on-times and off-times durations is evident. The addition of dopamine reduces the probability of observing long on-times and increases the probability of observing long off-times.
Mentions: Westudied the effect of conjugating dopamine to QDs on their blinking statistics.The probability distributions of on times, P(on), and off times, P(off), for QDs with and without conjugateddopamine are shown in Figures 7(a) and 7(b), respectively, as measured byextracting fluorescence time traces, such as shown in Figure 6(b), setting athreshold and calculating on and off times. Approximately 500 QDs were analyzedfrom 5 sets of movies, taken at 50-millisecond resolution for 100 seconds. Exceptfor the dopamine, the QDs and the experimental conditions were identical.Clearly, under these conditions, the conjugation of dopamine to the QD reducedthe on times and increasedthe off times.

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