Lanthanide-doped nanoparticles

Vetrone, F., Naccache, R., Mahalingam, V., Morgan, C.G., Capohianco, J.A., 2009. The active-core/active-shell approach a strategy to enhance the upconversionluminescence in lanthanide-doped nanoparticles. Adv. Fund. Mater. 19, 2924—2929. 

Lanthanide-doped nanoparticles represent a promising new class of luminescent probes. This is due to their excellent chemical and optical properties availability of multiple lanthanide ions providing different, well-separated emission wavelengths, size- and shape-independent luminescent properties, large effective Stokes shifts. 

Chen G., C. H. Yang, P. N. Prasad. Nanophotonics and Nanochemistry Controlling the Excitation Dynamics for Frequency Up- and Down-Conversion in Lanthanide-Doped Nanoparticles, Acc. Chem. Res. 46, 1474-1486 (2013). 

Generally, quantum size effects are not expected in lanthanide-doped nanoinsulators such as oxides since the Bohr radius of the exciton in insulating oxides, like Y2O3 and Gd2C>3, is very small. By contrast, the exciton Bohr radius of semiconductors is larger (e.g., 2.5 nm for CdS) resulting in pronounced quantum confinement effects for nanoparticles of about 2.5 nm or smaller (Bol et al., 2002). Therefore, a possible influence of quantum size effects on the luminescence properties of lanthanide ions is expected in semiconductor nanocrystals. 

In the above sections, our attention was primarily focused on the structural and optical properties of lanthanide doped in nanoparticles such as spherical QDs. Lanthanides doped in some other novel low-dimensional nanostructures including core-shell, one-dimensional (ID) nanowires and nanotubes, two-dimensional (2D) nanofilms, hollow nanospheres, 2D nanosheets and nanodisks have also attracted extensive attention. It is expected that their unique structures could result in unusual mechanical, electronic, optical and magnetic properties. So far few papers have been reported for lanthanide ions other than Eu3+ in these materials. Much attention is focused on the optical properties of Eu3+ ions in view of their very good spectroscopic properties. 

In brief, the core-shell technique allows one to prepare doped nanoparticles that contain no other dopant sites than those known from the corresponding bulk material, despite their small size, below 15 nm. The quantum efficiency of lanthanide ions can also be improved by surface modification of the nanoparticles. 

Newer immunodetection applications, and particularly the so-called microarrays, employ new fluorescent probes such as europium chelates (Scorilas et al., 2000), lanthanide oxide nanoparticles (Dosev et al., 2005 Nichkova et al., 2006), fluoro-phore loaded latex beads (Orth et al., 2003), dye-doped silica nanoparticles (Zhou and Zhou, 2004 Yao et al., 2006), and inorganic nanocrystals (Gerion et al., 2003 Geho et al., 2005). 

Wang, F. and Liu, X.G (2008) Upconversion multicolor fine-tuning visible to near-infrared emission from lanthanide-doped NaYF4 nanoparticles. Journal of the American Chemical Society, 130, 5642-5643. 

Single lanthanide-doped oxide nanoparticles as donors in fluorescence resonance energy transfer experiments. J. Phys. Chem. 2006 110 19264-19270. 88. 

Pedroni, M., PiccineUi, F., Passuello, T., Gioarola, M., Mariotto, G., Polizzi, S., et al., 2011. Lanthanide doped upconverting colloidal CaF2 nanoparticles prepared by a single-step hydrothermal method toward efficient materials with near infrared-to-near infrared upconversion emission. Nanoscale 3, 1456—1460. 

Fan XP, Pi DB, Wang F, Qiu JR, Wang MQ. Hydrothermal synthesis and luminescence behavior of lanthanide-doped GdF3 nanoparticles. IEEE Trans Nanotechnol 2006 5(2) 123. 

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