title: Nanoscintillator conjugates as photodynamic therapy-based radiosensitizers: calculation of required physical parameters.
abstract: The recent demonstration of nanoscale scintillators has led to interest in the combination of radiation and photodynamic therapy. In this model, scintillating nanoparticles conjugated to photosensitizers and molecular targeting agents would enhance the targeting and improve the efficacy of radiotherapy and extend the application of photodynamic therapy to deeply seated tumors. In this study, we calculated the physical parameters required for these nanoparticle conjugates to deliver cytotoxic levels of singlet oxygen at therapeutic radiation doses, drawing on the published literature from several disparate fields. Although uncertainties remain, it appears that the light yield of the nanoscintillators, the efficiency of energy transfer to the photosensitizers, and the cellular uptake of the nanoparticles all need to be fairly well optimized to observe a cytotoxic effect. Even so, the efficacy of the combination therapy will likely be restricted to X-ray energies below 300 keV, which limits the application to brachytherapy.
authors.affiliation: Laboratory of Bioengineering and Physical Science, NIBIB, National Institutes of Health, Bethesda, Maryland 20892, USA. morgann@mail.nih.gov
authors.forename: Nicole Y
authors.initials: NY
authors.lastname: Morgan
authors.forename: Gabriela
authors.initials: G
authors.lastname: Kramer-Marek
authors.forename: Paul D
authors.initials: PD
authors.lastname: Smith
authors.forename: Kevin
authors.initials: K
authors.lastname: Camphausen
authors.forename: Jacek
authors.initials: J
authors.lastname: Capala
mesh_terms: D053758:Nanoparticles; D010778:Photochemotherapy; D011838:Radiation-Sensitizing Agents / Q000737:chemistry*; D012588:Scintillation Counting
chemical_list: D011838:Radiation-Sensitizing Agents