Optical in situ size determination of single lanthanide-ion doped oxide nanoparticles

International audienceWe show that the size of a lanthanide-ion doped nanoparticle can be accurately determined from its luminosity. The optically determined size distribution is in very good agreement with the distribution obtained from transmission electron microscopy. These data confirm that single nanoparticles are visualized in microscopy experiments. Nanoparticles as small as 13 nm are detectable with integration times of 500 ms. (c) 2006 American Institute of Physics

Luminescent lanthanide-ion doped nanoparticles as singlebiomolecule labels and oxidant sensors

International audienceWe report on the single-particle properties of lanthanide-ion doped oxide nanoparticles. We have demonstrated that their size can be accurately determined from their luminosity. The optically determined size distribution is in very good agreement with the distribution obtained from transmission electron microscopy (TEM). We also showed that the photobleaching of these nanoparticles is related to a reduction process and that we can use it to sense in a concentration-dependent manner the presence of an oxidant like H 2O2. Finally, we propose a way to perform nanoparticle-protein coupling and to determine the protein-nanoparticle ratio at the single-particle level. © (2007) COPYRIGHT SPIE--The International Society for Optical Engineering

Counting the number of proteins coupled to single nanoparticles

International audienceWe implemented amine coating of lanthanide-ion doped oxide luminescent nanoparticles and coupling to a protein labeled with an organic fluorophore. We exploited the stepwise photobleaching of the organic fluorophores and their initial emission to count the number of proteins coupled to single nanoparticles. We thus precisely measured the distribution of the protein−nanoparticle ratio and showed that its maximum is different from the average ratio determined from ensemble measurements. The accurate quantification of the biomolecule−particle coupling opens up the possibility of selecting finely controlled conjugates

New biological labels based on functionalized YVO4:Eu nanoparticles

International audienceLanthanide-ion doped oxide (YVO4:Eu) nanoparticles were synthesized as aqueous colloids and functionalized by a bioactive silane shell to be used as fluorescent biological labels. Nanoparticles functionalized with guanidinium groups were able to act as artificial toxins which specifically target Na+ channels. They were individually detectable in live cardiac myocytes. Functionalized oxide nanoparticles appear as a new interesting tool, especially attractive for long-term single-molecule tracking due to their photo-stability and long luminescence lifetime. © 2005 Materials Research Society

Functionalized fluorescent oxide nanoparticles: Artificial toxins for sodium channel targeting and imaging at the single-molecule level

International audienceLanthanide ion-doped oxide nanoparticles were functionalized for use as fluorescent biological labels. These nanoparticles are synthesized directly in water, which facilitates their functionalization, and are remarkably photostable without emission intermittency. Nanoparticles functiqnalized with guanidinium groups act as artificial toxins and specifically target sodium channels. They are individually detectable in live cardiac myocytes, revealing a heterogeneous distribution of sodium channels. Functionalized oxide nanoparticles appear to be a novel tool that is particularly attractive for long-term single-molecule tracking