Photoluminescence of cerium fluoride and cerium-doped lanthanum fluoride nanoparticles and investigation of energy transfer to photosensitizer moleculesElectronic supplementary information (ESI) available: QY measurements; DPIX absorbance at different concentrations; physical size parameters of NPs; concentration and relative amounts of samples containing DPIX; Stern-Volmer plots of DPIX quenching; TCSPC fit results for samples containing DPIX; absorbance spectra of citrate-capped NPs; EDX spect

Ce x La 1− x F 3 nanoparticles have been proposed for use in nanoscintillator-photosensitizer systems, where excitation of nanoparticles by ionizing radiation would result in energy transfer to photosensitizer molecules, effectively combining the effects of radiotherapy and photodynamic therapy. Thus far, there have been few experimental investigations of such systems. This study reports novel synthesis methods for water-dispersible Ce 0.1 La 0.9 F 3 /LaF 3 and CeF 3 /LaF 3 core/shell nanoparticles and an investigation of energy transfer to photosensitizers. Unbound deuteroporphyrin IX 2,4-disulfonic acid was found to substantially quench the luminescence of large (>10 nm diameter) aminocaproic acid-stabilized nanoparticles at reasonable concentrations and loading amounts: up to 80% quenching at 6% w/w photosensitizer loading. Energy transfer was found to occur primarily through a cascade, with excitation of "regular" site Ce 3+ at 252 nm relayed to photosensitizer molecules at the nanoparticle surface through intermediate "perturbed" Ce 3+ sites. Smaller (