Integration of Fe₃O₄ with Bi₂S₃ for Multi-Modality Tumor Theranostics

The combination of reactive oxygen species (ROS)-induced chemodynamic therapy (CDT) and photothermal therapy (PTT) holds a promising application prospect for their superb anticancer efficiency. Herein, we created a novel Fe₃O₄@polydopamine (PDA)@bovine serum albumin (BSA)-Bi₂S₃ composite as a theranostic agent, by chemically linking the Fe₃O₄@PDA with BSA-Bi₂S₃ via the amidation between the carboxyl groups of BSA and the amino groups of PDA. In this formulation, the Fe₃O₄ NPs could not only work as a mimetic peroxidase to trigger Fenton reactions of the innate H₂O₂ in the tumor and generate highly cytotoxic hydroxyl radicals (•OH) to induce tumor apoptosis but also serve as the magnetic resonance imaging (MRI) contrast agent to afford the precise cancer diagnosis. Meanwhile, the PDA could prevent the oxidization of Fe₃O₄, thus supporting the long-term Fenton reactions and the tumor apoptosis in the tumor. The Bi₂S₃ component exhibits excellent photothermal transducing performance and computed tomography (CT) imaging capacity. In addition, the PDA and Bi₂S₃ endow the Fe₃O₄@PDA@BSA-Bi₂S₃ composite with an excellent photothermal transforming ability which could lead to tumor hyperthermia. All of these merits play the synergism with the tumor microenvironment and qualify the Fe₃O₄@PDA@BSA-Bi₂S₃ NPs for a competent agent in the MRI/CT-monitored enhanced PTT/CDT synergistic therapy. Findings in this research will evoke new interests in future cancer therapeutic strategies based on biocompatible nanomaterials.