Proceedings Article | 1 March 2012
Thomas Maldiney, Aurélie Lecointre, Bruno Viana, Aurélie Bessière, Didier Gourier, Michel Bessodes, Cyrille Richard, Daniel Scherman
KEYWORDS: Luminescence, In vivo imaging, Nanoparticles, Ultraviolet radiation, Optical properties, Liver, Silicates, Lanthanides, Ions, X-rays
Regarding its ability to circumvent the autofluorescence signal, persistent luminescence was recently shown to be a
powerful tool for in vivo imaging and diagnosis applications in living animal. The concept was introduced with
lanthanide-doped persistent luminescence nanoparticles (PLNP), from a lanthanide-doped silicate host
Ca0.2Zn0.9Mg0.9Si2O6:Eu2+, Mn2+, Dy3+ emitting in the near-infrared window. In order to improve the behaviour of these
probes in vivo and favour diagnosis applications, we showed that biodistribution could be controlled by varying the
hydrodynamic diameter, but also the surface charges and functional groups. Stealth PLNP, with neutral surface charge
obtained by polyethylene glycol (PEG) coating, can circulate for longer time inside the mice body before being uptaken
by the reticulo-endothelial system. However, the main drawback of this first generation of PLNP was the inability to
witness long-term monitoring, mainly due to the decay kinetic after several decades of minutes, unveiling the need to
work on new materials with improved optical characteristics. We investigated a modified silicate host, diopside
CaMgSi2O6, and increased its persistent luminescence properties by studying various Ln3+ dopants (for instance Ce, Pr,
Nd, Tm, Ho). Such dopants create electron traps that control the long lasting phosphorescence (LLP). We showed that
Pr3+ was the most suitable Ln3+ electron trap in diopside lattice, providing optimal trap depth, and resulting in the most
intense luminescence decay curve after UV irradiation. A novel composition CaMgSi2O6:Eu2+,Mn2+,Pr3+ was obtained
for in vivo imaging, displaying a strong near-infrared persistent luminescence centred on 685 nm, allowing improved and
sensitive detection through living tissues.
