Light emission properties and biological applications of lanthanide doped oxide nanoparticles

Yttrium vanadate particles doped with europium are studied for their applications as biomolecule labels. Two parts of our recent work will be presented. The first concerns the thermal treatment of particles incorporated in a silica matrix. After annealing at 1000°C and redispersion in water by dissolution of the silica matrix, the structural and optical properties are greatly improved : without any modification of size, the obtained nanoparticles appear as perfect single crystals of 33 nm and have the same emission properties as the bulk material. Their quantum yield is 37% for 10% europium doping and the emission lifetime is 0.8 ms. The second aspect concerns the functionalization of the nanoparticles by the sol-gel condensation of aminopropyltriethoxysilane at the surface of particles. The chemical accessibility of amino groups grafted on the particles is measured by reaction with an organic fluorescent tag FITC (fluorescein isothiocyanate). These amine-coated nanoparticles were coupled to a peptidic toxin via a cross-linker and allowed observation of the toxin motion bound to its membrane receptor.