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

[Image: see text] 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.