Dye-sensitized rare-earth-doped nanoparticles and MOF heterostructures for enhanced NIR-II fluorescence imaging and synergistic photothermal and photodynamic therapy

Early diagnosis and treatment of cancer are key problems for effective cancer therapy. Therefore, the development of multifunctional materials that can integrate imaging and therapeutic functions is of great importance. Lanthanide-doped nanoparticles@metal-organic frameworks (Ln-NPs@MOFs) offer an unprecedented opportunity to address this challenge, by combining the imaging capabilities of rare earth-doped nanoparticles with the photosensitizing properties of MOFs for photodynamic therapy (PDT). Here, we report a near-infrared (NIR) light-responsive nanoparticle based on a zirconium-porphyrin metal-organic framework (PCN-224) for synergistic photothermal and photodynamic therapy. Tetra(4-carboxyphenyl)porphyrin (TCPP) that constitutes the MOF framework serves as a natural photosensitizer, enabling efficient photodynamic therapy through Förster resonance energy transfer (FRET). The dye indocyanine green (ICG) was loaded into the MOF pores to sensitize the Ln nanoparticles, enhancing the upconversion fluorescence by 41 times and the downconversion fluorescence by 5 times, which is beneficial to the biological efficacy for imaging diagnosis. Meanwhile, ICG, a traditional photothermal agent, also imparts photothermal therapy capabilities to the system. Furthermore, the encapsulation of cancer cell membranes not only enhances biocompatibility but also improves the material's targeting towards cancer cells, thereby greatly enhancing the therapeutic effect. This dual-functional material provides a promising platform for the integration of cancer diagnosis and therapy.