Photoactivation of CdSe/ZnS quantum dots embedded in silica colloids |
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Authors: | Dembski Sofia Graf Christina Krüger Tim Gbureck Uwe Ewald Andrea Bock Anne Rühl Eckart |
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Affiliation: | 1. Lehrstuhl für Physikalische Chemie I Universit?t Würzburg Am Hubland, 97074 Würzburg (Germany);2. Physikalische Chemie, Institut für Chemie und Biochemie Freie Universit?t Berlin Takustr. 3, 14195 Berlin (Germany);3. Lehrstuhl für Zell‐ und Entwicklungsbiologie Biozentrum der Universit?t Würzburg Am Hubland, 97074 Würzburg (Germany);4. Abteilung und Lehrstuhl für Funktionswerkstoffe der Medizin und der Zahnheilkunde Pleicherwall 2, 97070 Würzburg (Germany) |
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Abstract: | A study of the influence of the local environment on the light-induced luminescence enhancement of CdSe/ZnS quantum dots (QD) embedded in silica colloids that are dispersed in various solvents is presented. The photoluminescence of the embedded QD is enhanced up to a factor of ten upon photoactivation by ultraviolet or visible light. This enhancement is strongly dependent on the local environment. The thickness-dependent permeability of the silica shell covering the QD controls the influence of the solvent on the QD. If foreign ions are present the activation state is stabilized after termination of the activation, whereas in their absence the process is partially reversible. A new qualitative model for the photoactivation of QD in various environments is developed. It comprises light-induced passivation and subsequent oxidation processes. The embedded QD also retain their fluorescence quantum yield inside living cells. Moreover, they can be activated for many hours in living cells by laser radiation in the visible regime. |
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Keywords: | multicore particles photoactivation photoluminescence quantum dots silica |
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