Tumor microenvironment-activated theranostic nanozymes for trimodal imaging-guided combined therapy

Synergistic therapy is expected to be a promising strategy for highly effective cancer treatment. However, the rational design of a simple and multifunctional nanoplatform still remains a grand challenge. Considering the nature of weak acidic, hypoxic, and H₂O₂ abundant tumor microenvironment, we constructed an indocyanine green (ICG) modified platinum nanoclusters (Pt NCs) decorated gold nanobipyramids (Au NBPs) to form the multifunctional nanocomposites (Au NBPs@Pt NCs-ICG) for multimodal imaging mediated phototherapy and chemodynamic cancer therapy. The photosensitizer ICG was covalently linked to Au NBPs@Pt NCs by bridging molecules of SH-PEG-NH₂ for both photodynamic therapy (PDT) and fluorescence imaging. Besides, Au NBPs@Pt NCs-ICG nanocomposites exhibited catalase- and peroxidase-like activities to generate O₂ and ·OH, which relieved the tumor hypoxia and upregulated antitumoral ROS level. Moreover, the combination of Au NBPs and ICG endowed the Au NBPs@Pt NCs-ICG with super photothermal conversion for effective photothermal imaging and therapy. In addition, the Au NBPs@Pt NCs-ICG nanoplatform displayed excellent X-ray computed tomography (CT) imaging ability due to the presence of high-Z elements (Au and Pt). Overall, our results demonstrated that Au NBPs@Pt NCs-ICG nanoplatform exhibited a multimodal imaging guided synergistic PTT/PDT/CDT therapeutic manners and held great potential as an efficient treatment for breast cancer.