Endoplasmic Reticulum-Localized Iridium(III) Complexes as Efficient Photodynamic Therapy Agents via Protein...

Area of Science:

• Photodynamic Therapy
• Chemical Biology
• Cancer Research

Background:

• Reactive oxygen species (ROS) like singlet oxygen and superoxide radicals are implicated in cell death pathways.
• The precise mechanisms of ROS-induced protein dysfunction and their role in photodynamic therapy (PDT) remain unclear.

Purpose of the Study:

• To investigate protein modifications induced by ROS generated from rationally designed iridium (III) complexes.
• To explore the potential of these complexes as effective PDT agents for cancer treatment.

Main Methods:

• Synthesis and characterization of novel iridium (III) complexes designed for ROS generation.
• Evaluation of PDT efficacy using low-energy irradiation and two-photon activation.
• Mass spectrometry to identify and characterize protein oxidation and photo-cross-linking modifications.

Main Results:

• The iridium (III) complexes demonstrated high singlet oxygen quantum yields (> 0.78), enabling effective PDT at low concentrations and low irradiation doses (≤ 1 J cm(-2)).
• Two distinct protein modifications, oxidation and photo-cross-linking, were identified as key mechanisms in PDT-induced cell death.
• These modifications predominantly occurred in the endoplasmic reticulum and mitochondria, leading to significant cancer cell death.

Conclusions:

• Rationally designed iridium (III) complexes are potent photoactivatable agents for generating ROS in PDT.
• The study elucidates specific protein modifications (oxidation and photo-cross-linking) as critical mediators of cancer cell death in PDT.
• This work presents a promising, biologically applicable PDT strategy utilizing advanced iridium (III) complexes.