1：Experimental Design and Method Selection:

The study designed an IPT-BT synergistic therapy combining interventional photothermal therapy (IPTT) and brachytherapy (BT) using HGNs. HGNs were synthesized via an in situ reduction method to serve as both photothermal agents and radiosensitizers. Theoretical models included the use of localized surface plasmon resonance (LSPR) for photothermal conversion and X-ray attenuation for radiosensitization.

2：Sample Selection and Data Sources:

Human pancreatic adenocarcinoma cell lines (SW1990 and PANC-1) were used for in vitro experiments. BALB/c nude mice with orthotopic SW1990 pancreatic tumors served as the in vivo model. Data were sourced from cell culture, animal studies, and various imaging and analytical techniques.

3：List of Experimental Equipment and Materials:

Equipment included scanning electron microscope (SEM), dynamic light scattering (DLS) instrument (Zetasizer Nano-ZS), X-ray photoelectron spectroscopy (XPS) system (Axis HSi), UV-visible spectrophotometer (SHIMADZU 2600), flow cytometer, infrared thermal imager, photoacoustic imaging system (MSOT inVision 128), bioluminescence imaging system (IVIS Spectrum Imaging System), and ultrasound imaging. Materials included liposomes (DOPE, DPPC, DSPE-PEG2000), gold precursors (HAuCl4·3H2O), reducing agents (hydroxylamine hydrochloride), cell culture reagents, and radioactive seeds (iodine-125).

4：5). Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: HGNs were synthesized and characterized. In vitro studies involved cell viability assays (MTT), clonogenic survival assays, apoptosis analysis (flow cytometry with Annexin V-PE/7-AAD), and DNA damage assessment (γ-H2AX staining). In vivo studies included biodistribution analysis using fluorescence and ICP-MS, photoacoustic imaging, thermal imaging during laser irradiation, and therapeutic efficacy evaluation in tumor-bearing mice with groups receiving different treatments (control, BT alone, HGNs + BT, HGNs + IPTT, HGNs + IPT-BT). Treatments involved intravenous injection of HGNs, implantation of 125I seeds under ultrasound guidance, and laser irradiation via interventional fiber.

5：Data Analysis Methods:

Data were analyzed using statistical methods (t-test) with significance set at P < 0.01. Software included Image J for immunohistochemical analysis and instruments' built-in software for imaging and spectroscopy data.