1：Experimental Design and Method Selection:

The study involved a one-step synthesis of EPL@CuSNPs nanocomposites by modifying copper sulfide nanoparticles with ε-polylysine (EPL) peptide. The rationale was to enhance stability and antibacterial activity through surface modification. Methods included UV-vis-NIR spectroscopy, TEM, DLS, XPS, infrared thermal imaging, fluorescence imaging, SEM, CLSM, MTT assay, and various biological assays to evaluate antimicrobial and antibiofilm activities.

2：Sample Selection and Data Sources:

Four isolates of Pseudomonas aeruginosa were used to study antimicrobial activity. NIH 3T3 cells were used for cytotoxicity and selectivity assays. Bacterial biofilms were formed in vitro using standard methods.

3：List of Experimental Equipment and Materials:

Equipment included UV-vis-NIR spectrometer (Shimadzu UV-3600), TEM (Tecnai G2 F20), DLS (Malvern Nano-ZS90), XPS (Axis Ultra DLD), infrared thermal imaging system (E50), fluorescence microscope (Axio Imager Z1), SEM (JSM-7500F), CLSM (Leica TCS SP8), and IVIS Lumina II imaging system. Materials included EPL, CuCl2·2H2O, Na2S·9H2O, DCFH-DA, EB, AO, DAPI, MTT, ONPG, and other chemicals from specified suppliers.

4：Experimental Procedures and Operational Workflow:

Synthesis of EPL@CuSNPs involved mixing CuCl2, EPL, and Na2S in water at 60°C for 2 hours, followed by dialysis. Antimicrobial assays involved incubating bacteria with nanocomposites, NIR laser irradiation (980 nm, 1.5 W/cm2, 3 min), and measuring OD600. Biofilm assays used crystal violet staining and CLSM. Cytotoxicity was assessed via MTT assay on NIH 3T3 cells. Procedures included staining, irradiation, imaging, and data collection as per described steps.

5：5 W/cm2, 3 min), and measuring ODBiofilm assays used crystal violet staining and CLSM. Cytotoxicity was assessed via MTT assay on NIH 3T3 cells. Procedures included staining, irradiation, imaging, and data collection as per described steps. Data Analysis Methods:

5. Data Analysis Methods: Data were analyzed using statistical methods (e.g., inhibition ratios, viability percentages), with software tools not specified but implied from equipment (e.g., image analysis for microscopy).