Synthesis of trypsin-protected CsPbCl₃ fluorescent nanocrystals for hydroxyl radical sensing

Water-dispersible perovskite nanocrystals (PNCs) show promising applications in recognizing ionic and molecular species because of their excellent optical properties. However, lead halide PNCs have some limitations when they are used as probes for molecular species sensing in aqueous media. Here, we introduce trypsin (Try) as a bioligand for the synthesis of cesium lead chloride (CsPbCl₃) PNCs with high water stability. The as-fabricated Try-CsPbCl₃ PNCs show λ_Em/Ex at 433/370 nm with a quantum yield of 17.26%. The fluorescence emission spectral characteristics of Try-CsPbCl₃ PNCs demonstrated that water-stable Try-CsPbCl₃ PNCs acted as a promising fluorescent probe for the detection of hydroxyl radical (^•OH) via turn-off mechanism. The Try-CsPbCl₃ PNCs-based turn-off fluorescence approach displayed good selectivity for hydroxyl radical in water, showing a wider linear range (0.01-5 µM) with a remarkable detection limit of 3.10 nM for hydroxyl radical. The Try-CsPbCl₃ PNCs were demonstrated to be a facile probe for sensing ^•OH in water samples, which signifies that Try-CsPbCl₃ PNCs exhibited broad applications for hydroxyl radical sensing in real samples.