Regensburg 2007 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 16: Colloids and Nanoparticles III
CPP 16.6: Talk
Tuesday, March 27, 2007, 18:15–18:30, H47
Photoactivation of Quantum Dots Controlled Embedded into Silica colloids — •Christina Graf1,2, Sofia Dembski2, Anne Bock2, Tim Krüger3, and Eckart Rühl1,2 — 1Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin — 2Institut für Physikalische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, — 3Theodor-Boveri-Institut für Biowissenschaften, Universität Würzburg, Am Hubland, 97074 Würzburg
Quantum dots (QD) are nowadays widely used as markers in life science. However, after the transfer into biological systems their fluorescence quantum yield (QY) is often reduced. Photoactivation with UV or visible light is a powerful tool to increase the photoluminescene (PL) of QD. Here, we present a study on the influence of the local environment on the photoactivation of QD. CdSe/ZnS QD embedded in silica colloids were studied in various liquids. Under continuous photoactivation with UV or visible light the PL of the embedded QD can be stably up to ten times enhanced and strongly depends on the local environment. Hereby, the thickness-dependent permeability of the silica shell controls the influence of the outer media on the QD. If foreign ions are present the activation can be fully retained after termination of the activation, while in their absence the process is partially reversible. Considering the present results, a new model for the photoactivation of QD in various environments is developed. It comprises photopassivation and a subsequent oxidation processes. The embedded QD also retain their QY inside living cells. Moreover, they can be long-time photoactivated in living cells.