1：Experimental Design and Method Selection:

The study designed GSH-AuNCs as fluorescence probes for Tc detection based on fluorescence quenching. The mechanism involves electrostatic interactions and electron transfer between Tc and AuNCs. Methods included synthesis of GSH-AuNCs, fluorescence spectroscopy for detection, and preparation of test papers for visual analysis.

2：Sample Selection and Data Sources:

Samples included aqueous solutions with Tc concentrations from 50 μg/L to 50 mg/L, and real tap water samples. Interfering substances (e.g., dopamine, metal ions) were used to test selectivity.

3：List of Experimental Equipment and Materials:

Equipment: JEM-2100 transmission electron microscope (HR-TEM), LS55 luminescence spectrometer (PerkinElmer), Cary 60 UV/Vis spectrometer (Agilent Technologies), Zetasizer Nano (Malvern Instruments Ltd.). Materials: Hydrogen tetrachloroaurate (HAuCl4·3H2O) from Sigma Aldrich, glutathione (GSH) from Aladdin, tetracycline from Macklin, and various chemicals from Tianjin Fengchuan Chemical Reagent Co.

4：Experimental Procedures and Operational Workflow:

Synthesis of GSH-AuNCs by mixing HAuCl4 and GSH, stirring at 70°C for 24 h. For Tc detection, aliquots of GSH-AuNCs were mixed with Tc solutions, and fluorescence spectra were recorded. Test papers were prepared by immersing filter paper in GSH-AuNCs solution and drying, then dropping Tc samples for visual observation under UV light.

5：Data Analysis Methods:

Fluorescence intensity at 590 nm was measured, and F/F0 ratio was calculated for quenching analysis. Linear regression was used for calibration curves. Zeta potential measurements and HR-TEM imaging were used for characterization.