Singlet oxygen photodynamic therapy

The most important application for singlet oxygen generators (SOGs), namely the anti-cancer treatment known as photodynamic therapy (PDT), is described elsewhere in this series (see Chapter 9.22). However, SOGs are also being evaluated in other areas, such as hard surface disinfectants, soaps and washing powders,73 and insecticides.74,75... 

Porphyrins and related structures have long been used in photodynamic therapy (PDT). In PDT, the photo-induced production of singlet oxygen is the toxifying... 

Singlet Oxygen and Photodynamic Therapy for Cancer Treatment... 

The ability of a range of 2,4,6-triaryl thio-, seleno- and telluro- pyrylium dyes to generate singlet oxygen and hence to function as sensitiseis for photodynamic therapy has been examined <99JMC3942,3953>. 

Singlet oxygen was discovered originally by Raab who first reported the photodynamic effect of dyestuffs, light, and oxygen [311]. The biomedical implications of this discovery have only recently been made clear, particularly by Dougherty and his co-workers, who have demonstrated the implications of the photodynamic effect in tumor therapy [312]. 

The reaction serves as an illustrative example of the synthetic utilization of the Te(II)—>Te(IV) two-electron shuttle. Another promising application is seen in photodynamic therapy in which tellurapyrylium dyes 119 can function as photosensitizers to produce either singlet oxygen or superoxide radical-anions (via electron transfer), thereby serving as cytotoxic agents. An important useful property of tellurapyrylium dyes is their absorbance in the near-infrared region where biological tissues are most important. 

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