Silica-Encapsulated Perovskite Nanocrystals for X-ray-Activated Singlet Oxygen Production and Radiotherapy Application.

Multicomponent systems consisting of lead halide perovskite nanocrystals (CsPbX 3 -NCs, X = Br, I) grown inside mesoporous silica nanospheres (NSs) with selectively sealed pores combine intense scintillation and strong interaction with ionizing radiation of CsPbX 3 NCs with the chemical robustness in aqueous environment of silica particles, offering potentially promising candidates for enhanced radiotherapy and radio-imaging strategies. We demonstrate that CsPbX 3 NCs boost the generation of singlet oxygen species ( 1 O 2 ) in water under X-ray irradiation and that the encapsulation into sealed SiO 2 NSs guarantees perfect preservation of the inner NCs after prolonged storage in harsh conditions. We find that the 1 O 2 production is triggered by the electromagnetic shower released by the CsPbX 3 NCs with a striking correlation with the halide composition (I 3 > I 3- x Br x > Br 3 ). This opens the possibility of designing multifunctional radio-sensitizers able to reduce the local delivered dose and the undesired collateral effects in the surrounding healthy tissues by improving a localized cytotoxic effect of therapeutic treatments and concomitantly enabling optical diagnostics by radio imaging.