Amphiphilic Polymer Ligand-Assisted Synthesis of Highly Luminescent and Stable Perovskite Nanocrystals for Sweat Fluorescent Sensing

The weak interfacial binding affinities of the inorganic perovskite core with ligands and high density of surface defect states inducethe facile detachment of surface ligands from nanocrystals (NCs), resulting in their poor colloidal stability and fluorescence in aqueous. In this work, apowerful ligand engineering strategy was proposed for eliminating thesurface defects and aggregation of the NCs. Using an amphiphilic polymeroctylamine-modified polyacrylic acid (OPA) as a capping ligand, the as-synthesized CsPbBr3NCs retain high photoluminescence intensity andstability by the modified ligand-assisted reprecipitation method. Theincrease in thefluorescence lifetime and NC size could also be observed,and how the NC particle size influencesfluorescence lifetime was furtherstudied. In addition, the water stability, photostability, and thermal stabilitywere significantly improved, and thefluorescence of NCs can maintain80.13% of the original value in water for 15 d. We further validated that thestrong binding affinity of OPA and oleylamine ligands with CsPbBr3NCs leads to a reduction in surface trap states, and a large amount of carboxyl groups of the OPA made the NCs preserve good water solubility. In addition, the OPA has the ability of adjusting the particle size of NCs. Furthermore, a wavelength-shifted colorimetric sensor based on these NCs was constructed for detection of Cl-in sweat, which enables the rapid and visual detection of Cl-with high accuracy and stability. Overall, theseCsPbBr3NCs synthesized by the ligand engineering strategy validated their wide applications in biomedical sensing fields.

Automated summary

This study proposed a powerful ligand engineering strategy to eliminate surface defects and aggregation of CsPbBr3nanocrystals (NCs), improving their colloidal stability and fluorescence. The as-synthesized NCs with amphiphilic polymer-modified ligands exhibited high photoluminescence intensity and stability. Furthermore, the NCs showed enhanced water, photostability and thermal stability. Additionally, a colorimetric sensor based on these NCs was successfully constructed for the detection of chloride ions in sweat, enabling rapid, visual and accurate detection.