A team led by Professor Gilles Gasser (Chimie ParisTech-PSL), in collaboration with the University of Barcelona and several international partners, has developed a new family of ruthenium-based photosensitizers that can be activated by near-infrared (NIR) light. This major advance for photodynamic cancer therapy has been published in the Journal of the American Chemical Society.

Innovative Photosensitizers to Overcome Current PDT Limitations. The researchers designed a new series of ruthenium polypyridyl complexes featuring π-extended COUBPY ligands. This unprecedented molecular architecture shifts absorption toward the red region of the spectrum, enabling efficient activation with NIR light and paving the way for deeper, less invasive treatments.

Enhanced Efficacy, Even in Low-Oxygen Tumor Environments. When activated by NIR light, these new compounds exhibit remarkable nanomolar phototoxicity in vitro. Their dual mode of action—Type I and Type II—ensures sustained efficacy, even within hypoxic tumor microenvironments where many conventional photosensitizers lose effectiveness.

Promising In Vivo Results for Lead Compound Ru6. The lead compound, Ru6, demonstrated strong antitumor activity in a mouse model of colorectal cancer. Following intratumoral injection and NIR light irradiation, tumor growth was significantly reduced, making Ru6 one of the first ruthenium-based photosensitizers to achieve such effects under single-photon NIR activation.

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