
Johannes Karges and his team have developed a new mechanism of activity against cancer cells.
Photo Credit: © RUB, Marquard
Scientific Frontline: Extended "At a Glance" Summary: Hypoxic Photodynamic Therapy
The Core Concept: A novel photodynamic therapy (PDT) approach utilizing a ruthenium-based active agent to effectively destroy cancer cells even within severe, oxygen-depleted (hypoxic) tumor environments.
Key Distinction/Mechanism: Traditional photodynamic cancer treatments rely on the presence of ambient oxygen to create cell-killing reactive oxygen species, making them largely ineffective in the oxygen-starved centers of fast-growing tumors. This newly developed therapy circumvents the need for molecular oxygen entirely. When oxygen is absent, intracellular iron coordinates with the active agent, triggering an ultra-fast metal-to-metal electron transfer from the excited ruthenium center to the iron center. This process converts naturally occurring hydrogen peroxide within the cell into highly lethal hydroxyl radicals, which cause fatal oxidative damage to the cancer cells.
Major Frameworks/Components:
- Photodynamic Therapy (PDT): An established cancer treatment method where an administered, inactive substance is activated via targeted light irradiation.
- Ruthenium-Based Active Agent (Ru(II) Polypyridine–Deferasirox Conjugate): The light-activated compound capable of entering an excited electronic state to drive the reaction.
- Metal-to-Metal Electron Transfer: The alternate, oxygen-independent chemical pathway where electrons transfer from the ruthenium center to an iron center.
- Hydroxyl Radicals: Highly reactive, cell-destroying molecules generated by the conversion of cellular hydrogen peroxide during the electron transfer process.











