Nanoscale\nMetal–Organic Layers for Radiotherapy–Radiodynamic\nTherapy

Abstract

Nanoscale metal–organic layers\n(nMOLs) are an emerging class\nof 2D crystalline materials formed by reducing the dimensionality\nof nanoscale metal–organic frameworks (nMOFs). nMOLs hold significant\npotential in biomedical applications by combining the structural and\ncompositional tunability of nMOFs and anisotropic properties of 2D\nnanomaterials. Here we report two novel nMOLs, Hf₁₂-Ir\nand Hf₆-Ir, based on Hf₁₂ and Hf₆ secondary building units (SBUs) and photosensitizing Ir­(bpy)­[dF­(CF₃)­ppy]₂⁺ derived ligands [bpy = 2,2′-bipyridine;\ndF­(CF₃)­ppy = 2-(2,4-difluoro­phenyl)-5-(trifluoro­methyl)­pyridine]\nfor radiotherapy (RT) and radiodynamic therapy (RDT). Upon X-ray irradiation,\nthe Hf₁₂ or Hf₆ SBUs in the nMOLs efficiently\nabsorb X-rays to enhance RT by producing hydroxyl radicals and to\nelicit RDT through the excitation of Ir­(bpy)­[dF­(CF₃)­ppy]₂⁺ derived ligands to generate singlet oxygen and\nsuperoxide anions. Hf₁₂-Ir and Hf₆-Ir promoted\neffective cell instant death through RDT and cell reproductive death\nthrough RT to elicit superb anticancer efficacy, resulting in >99%\ntumor regression at low X-ray doses of 0.5 × 5 Gy.