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Regioisomerization Strategy in Iridium(III) Complexes Achieving Enhanced Type I Photosensitization and Tumor
Feng Chen1, Hongbiao Ma1, Guoqing Wen1
1College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
Journal of Medicinal Chemistry
|June 16, 2025
Summary
Engineered iridium(III) complexes with specific regioisomer structures show enhanced photodynamic therapy. This design overcomes hypoxia, improving antitumor immunity and dendritic cell maturation for photoimmunotherapy.
Area of Science:
- Photochemistry
- Materials Science
- Immunology
Background:
- Molecular isomers possess identical compositions but differ in spatial arrangement, influencing physicochemical properties.
- Precise spatial arrangement of electron donors in iridium(III) complexes is crucial for tuning electronic and photophysical properties.
Purpose of the Study:
- To develop a regioisomer engineering strategy for constructing iridium(III) complexes with tailored properties for photoimmunotherapy.
- To investigate the impact of regioisomerism on photodynamic activity, reactive oxygen species generation, and antitumor immune response, particularly under hypoxic conditions.
Main Methods:
- Synthesis of two iridium(III) complexes (Ir1 and Ir2) using a regioisomer engineering strategy with precisely positioned triphenylamine electron donors.
- Characterization of electronic properties including bandgap, oxidation potential, and spin-orbit coupling (SOC).
- Evaluation of type I photodynamic activity under 633 nm irradiation, assessing reactive oxygen species (ROS) generation (O2•− and •OH) and immunogenic cell death (ICD) induction.
Main Results:
- The Ir2 complex, with strategically displaced donors, exhibited a contracted bandgap, reduced oxidation potential, and amplified SOC compared to Ir1.
- Ir2 demonstrated superior type I photodynamic activity, effectively generating ROS even under hypoxic conditions.
- Sustained ROS production by Ir2 induced potent ICD, leading to enhanced dendritic cell maturation and antitumor immunity.
Conclusions:
- Regioisomer engineering of iridium(III) complexes provides a molecular blueprint for developing oxygen-tolerant photosensitizers.
- This strategy effectively addresses the challenge of hypoxia in photoimmunotherapy, enhancing therapeutic outcomes.
- The developed complexes show promise for stimulating antitumor immunity through ROS-mediated ICD.
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