Multifunctional Monovalent Copper-Doped Carbon Dots for Synergistic Antibacterial-Antitumor Therapy.

Current breast cancer treatment regimens are confronted with three major challenges: monotonous therapeutic effects, intratumoral bacterium-induced drug resistance and immunosuppression, and off-target toxicity of drugs. To address these, in this study, a multifunctional nanoplatform of monovalent copper-doped arginine carbon dots (Arg-CuCDs) was developed. From the materials perspective, precisely controlled synthesis conditions enabled stable copper-doped carbon dots in the monovalent state, endowing them with heightened nanoenzyme activity and concurrently achieving red shift of fluorescence emission to the near-infrared region (∼700 nm). This facilitates simultaneous chemodynamic therapy (CDT) and deep tumor imaging. Functionally, its pH-dependent catalytic activity and acidic drug release behavior sensitively respond to the tumor microenvironment (TME) and selectively kill tumor cells. Crucially, Arg-CuCDs exert therapeutic effects by modulating tumor microbial community structure through bacterial membrane disruption, achieving synergistic antibacterial-antitumor therapy. Concurrently, from a disease diagnosis and treatment evaluation perspective, a sensitive fluorescence test strip was developed based on the fluorescence quenching caused by the internal filtration effect triggered by copper-amino coordination, for the dynamic monitoring of dopamine in the TME (the biomarker reflects tumor progression, metabolism, and treatment response). This "one stone, multiple birds" diagnosis and treatment strategy provides a promising strategy for developing emerging breast cancer treatment regimens.