Photodynamic therapy (PDT) combines photosensitive drugs with laser activation to treat cancer effectively. Metal-based photosensitizers like tin, lutetium, palladium, and ruthenium compounds have already entered clinical trials or received approval for PDT applications. However, conventional PDT mechanisms heavily depend on oxygen, limiting their effectiveness in hypoxic cancer environments. Developing innovative photosensitizers with alternative mechanisms of action is crucial for expanding PDT applications in cancer treatment.

Iridium Photocatalysts: A Breakthrough in Hypoxic Cancer Therapy

Professor Huang Huaiyi from Sun Yat-sen University has pioneered a novel approach to address the challenges of hypoxic cancer environments. His research focuses on selectively inducing NADH consumption to disrupt mitochondrial electron transport chains (ETC) and create redox imbalances that target cancer cells effectively.

Professor Huang designed and synthesized a groundbreaking octahedral cyclic metal Ir(III) photocatalyst, [Ir(ttpy)(pq)Cl]PF6 (where ttpy represents 4′-(p-tolyl)-2,2′:6′,2′-terpyridine and pq represents 3-phenylisoquinoline).

Key Features and Findings

• Abnormally High Excited-State Reduction Potential: The catalyst can photocatalytically oxidize NADH in biological media under hypoxic conditions.

• Selective Targeting of Cancer Cells: NAD· free radicals generated react synergistically to photoreduce cytochrome c, inducing redox imbalances in cancer cells while sparing normal cells.

• Low Dark Toxicity: This ensures reduced side effects during treatment.

• Phototoxicity in Hypoxic and Normoxic Conditions: The photocatalyst demonstrates high efficacy in diverse tumor environments.

This innovative photocatalytic redox imbalance approach offers a new direction for effective cancer photodynamic therapy.

Figure 1 Photoredox reaction of NADH and metallic iridium photocatalyst under 463nm blue light irradiation[1]
a. Colored lines represent spectra recorded every 5 minutes for 0.5 hours. The red arrow indicates the direction of change of absorbance with time; b. Stern-Volmer diagram of the interaction between NADH and the excited state of the metallic iridium photocatalyst; c. X-band EPR spectra of NAD• radicals captured by CYPMPO at different times after 463 nm light irradiation.

J&K Scientific exclusively supplies the Ir(III) photocatalyst developed by Professor Huang Huaiyi, supporting researchers in PDT and beyond.

Product Advantages

1. Excellent Photocatalytic Performance: Ideal for tumor photocatalytic research, organic synthesis, hydrogen production, and cell imaging.

2. Unique Excited-State Redox Potential: Functions as a versatile excited-state oxidant or reducing agent.

3. High Photostability: Ensures safe storage, easy handling, and efficient operation across diverse applications.

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References

1. Huang H, Banerjee S, Qiu K, et al. Targeted photoredox catalysis in cancer cells[J]. Nature chemistry, 2019, 11(11): 1041-1048.