Biocompatible Silica‐Coated Europium‐Doped CsPbBr 3 Nanoparticles with Luminescence in Water for Zebrafish Bioimaging

Cesium lead halide (CsPbX₃, X = Br, Cl, and I) nanocrystals (NCs) are widely concerned and applied in many fields due to the excellent photoelectric performance. However, the toxicity of Pb and the loss of luminescence in water limit its application in vivo. A stable perovskite nanomaterial with good bioimaging properties is developed by incorporating europium (Eu) in CsPbX₃ NCs followed with the surface coating of silica (SiO₂) shell (CsPbX₃:Eu@SiO₂). Through the surface coating of SiO₂, the luminescence stability of CsPbBr₃ in water is improved and the leakage of Pb²⁺ is significantly reduced. In particular, Eu doping inhibits the photoluminescence quantum yield reduction of CsPbBr₃ caused by SiO₂ coating, and further reduces the release of Pb²⁺. CsPbBr₃:Eu@SiO₂ nanoparticles (NPs) show efficient luminescence in water and good biocompatibility to achieve cell imaging. More importantly, CsPb(ClBr)₃:Eu@SiO₂ NPs are obtained by adjusting the halogen components, and green light and blue light are realized in zebrafish imaging, showing good imaging effect and biosafety. The work provides a strategy for advanced perovskite nanomaterials toward biological practical application.