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Photoinduced Enhancement in the Luminescence of Hydrophilic Quantum Dots Coated with Photocleavable Ligands

Impellizzeri, Stefania, Callan, Bridgeen, Callan, John F. and Raymo, Francisco M. (2012) Photoinduced Enhancement in the Luminescence of Hydrophilic Quantum Dots Coated with Photocleavable Ligands. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 134 (4). pp. 2276-2283. [Journal article]

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DOI: 10.1021/ja209873g


In search of strategies to photoactivate the luminescence of semiconductor quantum dots, we devised a synthetic approach to attach photocleavable 2-nitrobenzyl groups to CdSe-ZnS core-shell quantum dots coated with hydrophilic polymeric ligands. The emission intensity of the resulting nanostructured constructs increases by more than 60% with the photolysis of the 2-nitrobenzyl appendages. Indeed, the photoinduced separation of the organic chromophores from the inorganic nanoparticles suppresses an electron-transfer pathway from the latter to the former and is mostly responsible for the luminescence enhancement. However, the thiol groups anchoring the polymeric envelope to the ZnS shell also contribute to the photoinduced emission increase. Presumably, their photooxidation eliminates defects on the nanoparticle surface and promotes the radiative deactivation of the excited quantum dots. This effect is fully reversible but its magnitude is only a fraction of the change caused by the photocleavage of the 2-nitrobenzyl groups. In addition, these particular quantum dots can cross the membrane of model cells and their luminescence increases by similar to 80% after the intracellular photocleavage of the 2-nitrobenzyl quenchers. Thus, photoswitchable luminescent constructs with biocompatible character can be assembled combining the established photochemistry of the 2-nitrobenzyl photocage with the outstanding photophysical properties of semiconductor quantum dots and the hydrophilic character of appropriate polymeric ligands.

Item Type:Journal article
Faculties and Schools:Faculty of Life and Health Sciences > School of Pharmacy and Pharmaceutical Science
Faculty of Life and Health Sciences
Research Institutes and Groups:Biomedical Sciences Research Institute
Biomedical Sciences Research Institute > Pharmacy & Pharmaceutical Sciences
ID Code:22572
Deposited By: Professor John Callan
Deposited On:11 Jun 2012 13:50
Last Modified:12 Mar 2013 12:06

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