Colorimetric sensing of chloride in sweat based on fluorescence wavelength shift via halide exchange of CsPbBr3 perovskite nanocrystals

Considering the high importance of the rapid detection of chloride ion (Cl^-) in sweat for the diagnosis of fibrotic cysts, we have investigated the heterogeneous halide exchange between CsPbBr₃ perovskite nanocrystals (PNCs) in n-hexane and Cl^- in aqueous solution. The results show that CsPbBr₃ PNCs could achieve fast halide exchange with Cl^- in the aqueous phase under magnetic stirring at pH = 1, accompanied by a significant wavelength blue shift and vivid fluorescence color changes from green to blue. Therefore, a fluorescence wavelength shift-based colorimetric sensing of Cl^- based on the halide exchange of CsPbBr₃ PNCs has been developed to realize the rapid detection of Cl^- in sweat. Compared with the conventional fluorescence intensity-based method, this method is of high convenience since the whole procedure could be achieved within 5 min without any sample pretreatment (even no dilution), demonstrating promising application prospects. Graphical Abstract Fluorescence wavelength-shift based colorimetric sensing of chloride in sweat via halide exchange of CsPbBr₃ perovskite nanocrystals.