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

Abstract

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.