Halide Perovskite Nanocrystals with Enhanced Water Stability for Upconversion Imaging in a Living Cell

Halide perovskite nanomaterials are widely used in optoelectronics and photonics due to their outstanding luminescent properties, whereas their strong multiphoton absorption makes them prospective for bioimaging. Nonetheless, instability of perovskites in aqueous solutions is an important limitation that prevents their application in biology and medicine. Here, we demonstrate fluorescence and upconversion imaging in living cells by employing CsPbBr₃ nanocrystals (NCs) that show an improved water-resistance (at least for 24 h) after their coating as individual particles with various silica-based shells. The obtained phTEOS-TMOS@CsPbBr₃ NCs possess high quality, which we confirm with high-resolution transmission and scanning transmission electron microscopy, X-ray diffraction analysis, Fourier-transform infrared and energy-dispersive X-ray spectroscopies, as well as with fluorescence optical microscopy. The developed platform can make the halide perovskite NCs suitable for various bioimaging applications.