1：Experimental Design and Method Selection:

The method is based on fluorescence changes due to interactions between black phosphorus nanosheets (BPs), a perylene probe (probe 1), histone, and proteases. BPs act as quenchers, and probe 1 as the fluorescent indicator. Histone is used as a substrate for proteases, and its digestion regulates the fluorescence signal.

2：Sample Selection and Data Sources:

Samples include synthesized probe 1, commercially obtained BPs, histone, trypsin, and other proteins (e.g., BSA, cytochrome C, HRP, lysozyme). Human serum and urine samples were obtained from local hospitals and volunteers.

3：List of Experimental Equipment and Materials:

Equipment includes ultrasonic cell pulverizer, centrifuge, Zetasizer NanoZS for zeta potential measurement, TEM, SEM, AFM, XPS, Raman spectrometer, XRD, and fluorescence spectrometer. Materials include black phosphorus crystals, NMP, histone, trypsin, inhibitors (benzamidine hydrochloride, soybean inhibitor), and various proteins.

4：Experimental Procedures and Operational Workflow:

BPs were prepared by liquid exfoliation in NMP with sonication and centrifugation. Fluorescence quenching and recovery experiments involved mixing probe 1 with BPs and histone, followed by protease addition. Fluorescence spectra were recorded after stabilization. Trypsin sensing involved incubating histone with trypsin, then adding to a mixture of probe 1 and BPs. Selectivity and inhibitor screening followed similar protocols.

5：Data Analysis Methods:

Fluorescence intensity changes were monitored at 545 nm. Quenching efficiency and inhibition efficiency were calculated. Linear regression was used for calibration curves. IC50 values were determined for inhibitors.