Optimized Scintillator YAG:Pr Nanoparticles for X-ray Inducible Photodynamic Therapy.

We describe a sol-gel synthetic method for the production of praseodymium-doped yttrium aluminum garnet (YAG) nanoparticles suitable for X-ray inducible photodynamic therapy (X-PDT). Our sol-gel based approach was optimized by varying temperature and time of calcination, resulting in nanoparticles that were smooth, spherical, and 50-200 nm in crystallite size. The powders were uniformly coated with a thin (10 nm) layer of silica to facilitate surface conjugation with functional moieties. Measurements of photon flux revealed that coated and uncoated powders emitted a similar photon emission spectrum in response to 50 keVp X-rays. We also determined that the presence of silica did not significantly reduce flux and the emission peak had a maximum at approximately 320 nm. Thus, these YAG:Pr powders are suitable candidates for future in vivo X-PDT studies.