X-ray-induced nanoparticle-based photodynamic therapy of cancer

Abstract

Aim: In this study, Ce3+-doped lanthanum(III) fluoride (LaF3:Ce3+) nanoparticles were synthesized by a wet-chemistry method in dimethyl sulfoxide (DMSO) and their application as an intracellular light source for photodynamic activation was demonstrated. Materials & methods: The LaF3:Ce3+/DMSO nanoparticles have a strong green emission with a peak at approximately 520 nm, which is effectively overlapped with the absorption of protoporphyrin IX (PPIX). The nanoparticles were encapsulated into poly(D,L-lactide-co-glycolide (PLGA) microspheres along with PPIX. Upon irradiation with x-rays (90 kV), energy transfer from the LaF3:Ce3+/DMSO nanoparticles to PPIX occurs and singlet oxygen is generated for cancer cell damage. Results: The LaF3:Ce3+/DMSO/PLGA or LaF3:Ce3+/DMSO/PPIX/PLGA microspheres alone caused only sublethal cytotoxicity to the cancer cells. Upon x-ray irradiation, the LaF3:Ce3+/DMSO/PPIX/PLGA microspheres induced oxidative stress, mitochondrial damage and DNA fragmentation on prostate cancer cells (PC3). Discussion: The results indicate that x-rays can activate LaF3:Ce3+ and PPIX nanocomposites, which can be a novel method for cancer destruction. Original submitted 7 June 2013; Revised submitted 25 September 2013