Cancer deaths are mainly caused by tumor metastases. However, tumor ablation therapies can only target the primary tumor but not inhibit tumor metastasis. Herein, a multifunctional covalent organic framework (COF)-based nanocomposite is designed for synergetic photo-, chemodynamic- and immunotherapies. Specifically, the synthesized COF possesses the ability to produce singlet oxygen under the 650 nm laser irradiation. After being metallized with FeCl3, p-phenylenediamine is polymerized on the surface of COF with Fe3+ as the oxidant. The obtained poly(p-phenylenediamine) can be used for photothermal therapy. Meanwhile, the overexpressed H2O2 in the tumor would be further catalyzed and decomposed into hydroxyl radicals (•OH) by the Fe3+/Fe2+ redox couple via Fenton reaction. Intriguingly, the increase of temperature caused by photothermal therapy can accelerate the production of •OH. Moreover, the tumor-associated antigen induced a robust antitumor immune response and effectively inhibited tumor metastasis in the presence of anti-PD-L1 checkpoint blockade. Such a COF-based multifunctional nanoplatform provides an efficacious treatment strategy for both the primary tumor and tumor metastasis.
Keywords: chemodynamic therapy; covalent organic framework; immunotherapy; phototherapy; poly(p-phenylenediamine).