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Highlights in Chemical Technology

Chemical technology news from across RSC Publishing.

A bright future for photodynamic therapy?

15 February 2006

Quantum dots decorated with iridium complexes that have potential in photodynamic therapy (PDT) treatment of cancer have been developed by chemists in Taiwan. 

Quantum dot composites


The system developed by Pi-Tai Chou's team at the National Taiwan University and National Tsing Hua University has two functions. Firstly, it has a high enough emission from the luminescent CdSe/ZnS quantum dot for use in medical imaging. Secondly, the iridium complexes are positioned in a way that enables them to sensitize oxygen molecules to produce a toxic form, singlet oxygen, on exposure to light. 

Quantum dots have applications in diagnostics, bio-imaging, and as photosensitizing agents. PDT, which involves using a photosensitizing agent to produce toxic singlet oxygen to destroy cancer cells, has been shown to be as effective as surgery or radiation therapy in destroying and is less invasive. CdSe quantum dots have been investigated for use in these systems, but so far have shown fairly low levels of singlet oxygen generation.

'This system should greatly extend the usefulness in both research fields of bio-imaging and photodynamic therapy' said Pi-Tai Chou.

"PDT has been shown to be as effective as surgery or radiation therapy and is less invasive."

The group plan to develop a three-in-one system in which a specific target agent, such as folic acid, could be incorporated with the iridium groups. This would allow cell recognition properties in the quantum dot system as well as the imaging and PDT properties. 

Katherine Vickers


J-M Hsieh, M-L Ho, P-W Wu, P-T Chou, T-T Tsai and Y Chi, Chem. Commun., 2006, 615-617 (DOI: 10.1039/B517368J)