Bimetallic Complex-Meditated Radiotherapy-Radiodynamic Therapy In Vivo

Iridium complexes have excellent photophysical properties such as large stoke shift,high quantum yield,and long-lasting phosphorescence lifetime,and have long-term development in the field of luminescent materials.However,in the field of biomedicine,due to the limitation of the excitation wavelength,its development in this field has been limited.X-ray is an important physical excitation for deep tumor treatment.However,X-ray cannot effectively activate most conventional organic/inorganic photosensitizers?PSs?because of a mismatch in the apparent energy between the X-ray photon energy?Kev-Mev?and the singlet-triplet energy gap?1-3 e V?of PS.Fortunately,the bimetallic complex of the Ir₄Ho₂ photosensitizer is proposed,which can absorb X-rays directly to excite the photosensitizer,thus can lift the restriction of the excitation light of the metal iridium complex,and make full use of the excellent photophysical properties of metal iridium complex.Then,the Ir₄Ho₂ of Holmium???and [?pq?2Ir?H2dcppy?]+?pq = 2-phenylquionline,H2 dcppy = 2,2'-Bipyridine-3,3'-dicarboxylic acid?and their applications in radiotherapy-radiodynamic therapy?RT-RDT?were report.Upon X-ray irradiation,the Holmium???in Ir₄Ho₂ efficiently absorb X-rays,and elicit RDT through the directly or indirectly excitation of [?pq?2Ir?H2dcppy?]+ derived ligands to generate singlet oxygen.At the same time,the heavy atoms of Ir???and Ho???in Ir₄Ho₂ can effectively deposit X-rays to generate more hydroxyl radicals,thereby achieving the effect of radiosensitization.In this way,an efficient radiotherapy-radiodynamic therapy?RT-RDT?can be achieved,thereby providing a better tumor-suppressing effect.At the same time,under the excitation of medical isotope 18F-FDG,the radiation luminescent properties of Ir₄Ho₂ were studied.