Xavier Le Guével1, Christian Spies2, Nicole Daum3, Gregor Jung2, and Marc Schneider1()
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1Pharmaceutical Nanotechnology, Saarland University, D-66123 Saarbrücken, Germany2Department of Biophysical Chemistry, Saarland University, D-66123 Saarbrücken, Germany
3Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Center for Infection Research, D-66123 Saarbrücken, Germany
Metal nanoclusters, peptide, fluorescence, cellular uptake
A panel of silver nanoclusters (Ag NCs) protected by glutathione has been produced by collecting them on a plastic surface during an interfacial etching process. Blue-green, yellow and red emitting Ag NCs with size smaller than 2 nm exhibited distinct fluorescence properties (both emission and lifetime). In particular, the yellow emitting Ag NCs were found to reach a very high quantum yield of over 60% with a monoexponential fluorescence lifetime. These labels show no bleaching and high photostability over time and a high stability for a wide range of pH values. Cytotoxicity tests demonstrated the viability in the presence of of these luminescent probes even at high concentration (1 mg/mL). Cell studies confirmed the uptake of Ag NCs in epithelial lung cancer cells by an endocytotic process. These results show the high potential of fluorescent noble metal nanoclusters for biolabeling and imaging as alternatives to the standard fluorescent probes such as quantum dots or organic dyes.