Colorectal Tumor Microenvironment-Activated Bio-Decomposable and Metabolizable Cu2 O@CaCO3 Nanocomposites for Synergistic Oncotherapy.

Rational design of tumor microenvironment (TME)-activated nanocomposites provides an innovative strategy to construct responsive oncotherapy. In colorectal cancer (CRC), the specific physiological features are the overexpressed endogenous H2 S and slightly acidic microenvironment. Here, a core-shell Cu2 O@CaCO3 nanostructure for CRC "turn-on" therapy is reported. With CaCO3 responsive to pH decomposition and Cu2 O responsive to H2 S sulfuration, Cu2 O@CaCO3 can be triggered "on" into the therapeutic mode by the colorectal TME. When the CaCO3 shell decomposes and releases calcium in acidic colorectal TME, the loss of protection from the CaCO3 shell exposes the Cu2 O core to be sulfuretted by H2 S to form metabolizable Cu31 S16 nanocrystals that gain remarkably strong near-infrared absorption. After modifying hyaluronic acid, Cu2 O@CaCO3 can achieve synergistic CRC-targeted and TME-triggered photothermal/photodynamic/chemodynamic/calcium-overload-mediated therapy. Moreover, it is found that the generation of hyperthermia and oxidative stress from Cu2 O@CaCO3 nanocomposites can efficiently reprogram the macrophages from the M2 phenotype to the M1 phenotype and initiate a vaccine-like immune effect after primary tumor removal, which further induces an immune-favorable TME and intense immune responses for anti-CD47 antibody to simultaneously inhibit CRC distant metastasis and recurrence by immunotherapy.