Thermally stable and hydrophilic CsPbBr3/mPEG-NH2 nanocrystals with enhanced aqueous fluorescence for cell imaging

Abstract

The poor stability of fully inorganic halide perovskite nanocrystals (PNCs) has always restricted their wider application, especially in cell imaging. It has attracted more and more attention to use ligand engineering to improve the stability of PNCs. In this work, CsPbBr₃/mPEG-NH₂ NCs were synthesized using a highly biocompatible functional polymer, methoxypolyethylene glycol amine, as the capping ligand. The as-prepared CsPbBr₃/mPEG-NH₂ NCs exhibited superior water solubility as a result of the hydrophilic properties of mPEG-NH₂. More shockingly, a significantly enhanced fluorescence intensity was found when CsPbBr₃/mPEG-NH₂ NCs were dispersed in water for a period of time. Correspondingly, the fluorescence quantum yield increased from the initial 16% to 41% a week later. Meanwhile, the thermal stability of the product has been greatly improved; about 80% of the initial PL intensity was still maintained after heating the product to 100 °C. Finally, we directly utilized the CsPbBr₃/mPEG-NH₂ NCs as luminescent probes for cell imaging for the first time.