Water-ultrastable perovskite CsPbBr3 nanocrystals for fluorescence-enhanced cellular imaging

Metal halide perovskites have attracted much attention in biomedicine because of their excellent fluorescence energy conversion properties; however, poor water-stability and cytotoxicity limit its applications as a biomedical tracer, especially in cellular imaging. Herein, water-ultrastable perovskites CsPbBr3:Cs4PbBr6 nanocrystals (NCs) encapsulated in chitosan are fabricated successfully using a water-triggered method. The as-synthesized CsPbBr3:Cs4PbBr6@CS (chitosan, CS) nanoparticles in water display enhanced fluorescence emission for 35 days. Further, the viability of glioma cells (U87 cells) incubated with different concentrations of CsPbBr3:Cs4PbBr6@CS nanoparticles (0-20 mu g center dot ml(-1)) for 24 h is found to be higher than 90%. In artificial body fluid, analyses using laser confocal microscopy, the standard Cell Counting Kit-8 (CCK-8) method, and flow cytometry demonstrated the good water ultrastability and high biocompatibility performance of CsPbBr3:Cs4PbBr6@CS nanoparticles in cellular imaging. Overall, the water-ultrastable halide perovskites support promising perspectives in biological cell tracing and intelligent medical technology.