Porphyrin-Based Lanthanide Metal-Organic Layers Amplify the Reactive Oxygen Species Storm for Photodynamic Therapy, and Photoresponsive Radioactive UO22+ Ions.

Porphyrin derivatives employed for photodynamic therapy (PDT) readily undergo intense π-π stacking, triggering drastic quenching of fluorescence and reactive oxygen species (ROS), which severely restricts their practical utilization in PDT research. In this work, meso-tetrakis(4-carboxyphenyl)porphyrin (TCPP) was adopted as an organic linker to coordinate with binuclear Eu(III)-complex secondary building units (SBUs), affording a two-dimensional metal-organic layer (Eu-TCPP) capable of generating light-triggered massive ROS bursts. Combined electron paramagnetic resonance (EPR) characterizations and targeted fluorescent probes collectively validate that Eu-TCPP is able to simultaneously produce abundant type I and type II ROS cascades upon low-power photoirradiation. Such robust ROS cascades can not only provoke pronounced apoptotic damage toward tumor cells, but also achieve nearly complete elimination of solid tumors in xenograft tumor-bearing mouse models. Moreover, Eu-TCPP displays a distinct photoluminescence turn-on response toward radioactive uranyl ions (UO22+). This study not only advances the crystal engineering of photosensitizers built from lanthanide metal-organic frameworks (Ln-MOFs), but also establishes a versatile paradigm for fabricating multifunctional Ln-MOF integrated theranostic platforms.