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Fluorescence lifetime imaging and FRET-induced intracellular redistribution of Tat-conjugated quantum dot nanoparticles through interaction with a phthalocyanine photosensitiser.

Abstract
The interaction of Tat-conjugated PEGylated CdSe/ZnS quantum dots (QD) with the amphiphilic disulfonated aluminium phthalocyanine photosensitiser is investigated in aqueous solution and in a human breast cancer cell line. In aqueous solution, the QDs and phthalocyanine form stable nanocomposites. Using steady-state and time-resolved fluorescence measurements combined with singlet oxygen detection, efficient Förster resonance energy transfer (FRET) is observed with the QDs acting as donors, and the phthalocyanine photosensitiser, which mediates production of singlet oxygen, as acceptors. In cells, the Tat-conjugated QDs localise in lysosomes and the QD fluorescence lifetimes are close to values observed in aqueous solution. Strong FRET-induced quenching of the QD lifetime is observed in cells incubated with the nanocomposites using fluorescence lifetime imaging microscopy (FLIM). Using excitation of the QDs at wavelengths where phthalocyanine absorption is negligible, FRET-induced release of QDs from endo/lysosomes is confirmed using confocal imaging and FLIM, which is attributed to photooxidative damage to the endo/lysosomal membranes mediated by the phthalocyanine acceptor.
AuthorsElnaz Yaghini, Francesca Giuntini, Ian M Eggleston, Klaus Suhling, Alexander M Seifalian, Alexander J MacRobert
JournalSmall (Weinheim an der Bergstrasse, Germany) (Small) Vol. 10 Issue 4 Pg. 782-92 (Feb 26 2014) ISSN: 1613-6829 [Electronic] Germany
PMID24031023 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
Copyright© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Chemical References
  • Indoles
  • Isoindoles
  • Photosensitizing Agents
  • tat Gene Products, Human Immunodeficiency Virus
  • phthalocyanine
Topics
  • Fluorescence Resonance Energy Transfer (methods)
  • Humans
  • Indoles (pharmacology)
  • Intracellular Space (metabolism)
  • Isoindoles
  • MCF-7 Cells
  • Microscopy, Fluorescence
  • Nanoparticles (chemistry)
  • Optical Imaging (methods)
  • Photosensitizing Agents (pharmacology)
  • Quantum Dots (metabolism)
  • tat Gene Products, Human Immunodeficiency Virus (metabolism)

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