Construction and in vitro evaluation of a BiOCl-based targeted photodynamic therapy system for HER2-positive breast cancer

This study aimed to construct a targeted photodynamic synergistic therapy system (T-BOC) based on BiOCl nanosheets conjugated with Trastuzumab and evaluate its therapeutic efficacy and biosafety in vitro as a low-toxicity strategy for HER2-positive breast cancer. BiOCl nanosheets were synthesized via hydrothermal methods and characterized for morphology, size, charge, and crystallinity. Trastuzumab conjugation was validated by Cy5.5 labeling and SDS-PAGE. ROS generation was measured via ESR. Cytotoxicity and viability in SK-BR-3 and BT-474 cells were assessed using CCK-8, and PDT efficacy was evaluated via apoptosis assays. Uniform, two-dimensional BiOCl nanosheets were successfully synthesized and conjugated with Trastuzumab to form T-BOC. Upon light activation, T-BOC exhibited enhanced ROS generation and significant photodynamic cytotoxicity. Cytotoxicity assays indicated minimal toxicity below 100 μg/mL, with cell viability exceeding 90 %, demonstrating good biocompatibility. The BiOCl-based T-BOC system exhibited excellent in vitro therapeutic efficacy and biosafety, offering a novel strategy for targeted photodynamic therapy in HER2-positive breast cancer. This system holds promise for future personalized and precision treatment of malignant tumors.