A Photodynamic and Photochemotherapeutic Platinum-Iridium Charge-Transfer Conjugate for Anticancer Therapy

Huayun Shi*, Oliver W.L. Carter, Fortuna Ponte, Cinzia Imberti, Miguel A. Gomez-Gonzalez, Fernando Cacho-Nerin, Paul D. Quinn, Julia E. Parker, Emilia Sicilia*, Huaiyi Huang*, Peter J. Sadler*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

The novel hetero-dinuclear complex trans,trans,trans-[PtIV(py)2(N3)2(OH)(μ-OOCCH2CH2CONHCH2-bpyMe)IrIII(ppy)2]Cl (Pt-Ir), exhibits charge transfer between the acceptor photochemotherapeutic Pt(IV) (Pt-OH) and donor photodynamic Ir(III) (Ir-NH2) fragments. It is stable in the dark, but undergoes photodecomposition more rapidly than the Pt(IV) parent complex (Pt-OH) to generate Pt(II) species, an azidyl radical and 1O2. The Ir(III)* excited state, formed after irradiation, can oxidise NADH to NAD⋅ radicals and NAD+. Pt-Ir is highly photocytotoxic towards cancer cells with a high photocytotoxicity index upon irradiation with blue light (465 nm, 4.8 mW/cm2), even with short light-exposure times (10–60 min). In contrast, the mononuclear Pt-OH and Ir-NH2 subunits and their simple mixture are much less potent. Cellular Pt accumulation was higher for Pt-Ir compared to Pt-OH. Irradiation of Pt-Ir in cancer cells damages nuclei and releases chromosomes. Synchrotron-XRF revealed ca. 4× higher levels of intracellular platinum compared to iridium in Pt-Ir treated cells under dark conditions. Luminescent Pt-Ir distributes over the whole cell and generates ROS and 1O2 within 1 h of irradiation. Iridium localises strongly in small compartments, suggestive of complex cleavage and excretion via recycling vesicles (e.g. lysosomes). The combination of PDT and PACT motifs in one molecule, provides Pt-Ir with a novel strategy for multimodal phototherapy.

Original languageEnglish
Article numbere202400476
JournalAngewandte Chemie - International Edition
Volume63
Issue number23
DOIs
Publication statusPublished - 3 Jun 2024

Keywords

  • Anticancer
  • Heterometallic complex
  • Phototherapy
  • Synchrotron X-rays
  • TDDFT

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