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Photophysical behaviors of single fluorophores localized on zinc oxide nanostructures.

Fu Y, Zhang J, Lakowicz JR - Int J Mol Sci (2012)

Bottom Line: In this report we studied photophysical behaviors of single fluorophores in proximity to zinc oxide nanostructures by single-molecule fluorescence spectroscopy and time-correlated single-photon counting (TCSPC).Single fluorophores on ZnO surfaces showed enhanced fluorescence brightness to various extents compared with those on glass; the single-molecule time trajectories also illustrated pronounced fluctuations of emission intensities, with time periods distributed from milliseconds to seconds.The fluorescence fluctuation dynamics were found to be inhomogeneous from molecule to molecule and from time to time, showing significant static and dynamic disorders in the interfacial electron transfer reaction processes.

View Article: PubMed Central - PubMed

Affiliation: Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland School of Medicine, 725 Lombard Street, Baltimore, MD 21201, USA; E-Mails: jianzhang@umaryland.edu (J.Z.); jlakowicz@umaryland.edu (J.R.L.).

ABSTRACT
Single-molecule fluorescence spectroscopy has now been widely used to investigate complex dynamic processes which would normally be obscured in an ensemble-averaged measurement. In this report we studied photophysical behaviors of single fluorophores in proximity to zinc oxide nanostructures by single-molecule fluorescence spectroscopy and time-correlated single-photon counting (TCSPC). Single fluorophores on ZnO surfaces showed enhanced fluorescence brightness to various extents compared with those on glass; the single-molecule time trajectories also illustrated pronounced fluctuations of emission intensities, with time periods distributed from milliseconds to seconds. We attribute fluorescence fluctuations to the interfacial electron transfer (ET) events. The fluorescence fluctuation dynamics were found to be inhomogeneous from molecule to molecule and from time to time, showing significant static and dynamic disorders in the interfacial electron transfer reaction processes.

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(a) A SEM image of ZnO; (b) Spectra of Cy5/PVA deposited on Quartz glass (black) and ZnO film (red), the Cy5 concentration for spin coating is around 0.1 μM. (a) (b)
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f1-ijms-13-12100: (a) A SEM image of ZnO; (b) Spectra of Cy5/PVA deposited on Quartz glass (black) and ZnO film (red), the Cy5 concentration for spin coating is around 0.1 μM. (a) (b)

Mentions: SEM images reveal that ZnO film consists of hexagonal ZnO nanoclusters with a mean diameter of 100 nm (Figure 1a). Ensemble emission spectra of Cy5 on glass and ZnO surface with 630 nm excitation are shown in Figure 1b. It has been observed that the emission intensity increases approximately 10-fold as the dye molecules deposited on ZnO nanoparticle surface. In the presence of ZnO nanoparticles, the emission spectrum is slightly red-shifted; this can be contributed to the electronic coupling of the fluorophore and electronic states of the semiconductor [36].


Photophysical behaviors of single fluorophores localized on zinc oxide nanostructures.

Fu Y, Zhang J, Lakowicz JR - Int J Mol Sci (2012)

(a) A SEM image of ZnO; (b) Spectra of Cy5/PVA deposited on Quartz glass (black) and ZnO film (red), the Cy5 concentration for spin coating is around 0.1 μM. (a) (b)
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3472795&req=5

f1-ijms-13-12100: (a) A SEM image of ZnO; (b) Spectra of Cy5/PVA deposited on Quartz glass (black) and ZnO film (red), the Cy5 concentration for spin coating is around 0.1 μM. (a) (b)
Mentions: SEM images reveal that ZnO film consists of hexagonal ZnO nanoclusters with a mean diameter of 100 nm (Figure 1a). Ensemble emission spectra of Cy5 on glass and ZnO surface with 630 nm excitation are shown in Figure 1b. It has been observed that the emission intensity increases approximately 10-fold as the dye molecules deposited on ZnO nanoparticle surface. In the presence of ZnO nanoparticles, the emission spectrum is slightly red-shifted; this can be contributed to the electronic coupling of the fluorophore and electronic states of the semiconductor [36].

Bottom Line: In this report we studied photophysical behaviors of single fluorophores in proximity to zinc oxide nanostructures by single-molecule fluorescence spectroscopy and time-correlated single-photon counting (TCSPC).Single fluorophores on ZnO surfaces showed enhanced fluorescence brightness to various extents compared with those on glass; the single-molecule time trajectories also illustrated pronounced fluctuations of emission intensities, with time periods distributed from milliseconds to seconds.The fluorescence fluctuation dynamics were found to be inhomogeneous from molecule to molecule and from time to time, showing significant static and dynamic disorders in the interfacial electron transfer reaction processes.

View Article: PubMed Central - PubMed

Affiliation: Center for Fluorescence Spectroscopy, Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland School of Medicine, 725 Lombard Street, Baltimore, MD 21201, USA; E-Mails: jianzhang@umaryland.edu (J.Z.); jlakowicz@umaryland.edu (J.R.L.).

ABSTRACT
Single-molecule fluorescence spectroscopy has now been widely used to investigate complex dynamic processes which would normally be obscured in an ensemble-averaged measurement. In this report we studied photophysical behaviors of single fluorophores in proximity to zinc oxide nanostructures by single-molecule fluorescence spectroscopy and time-correlated single-photon counting (TCSPC). Single fluorophores on ZnO surfaces showed enhanced fluorescence brightness to various extents compared with those on glass; the single-molecule time trajectories also illustrated pronounced fluctuations of emission intensities, with time periods distributed from milliseconds to seconds. We attribute fluorescence fluctuations to the interfacial electron transfer (ET) events. The fluorescence fluctuation dynamics were found to be inhomogeneous from molecule to molecule and from time to time, showing significant static and dynamic disorders in the interfacial electron transfer reaction processes.

Show MeSH
Related in: MedlinePlus