10. Principle: A photosensitizer is administered to the target tissue, for example a cancerous tumour. Then light is shined onto the target tissue, which is absorbed by the photosensitizer and causes generation of reactive oxygen species.
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12. The photosensitizer moves from its ground state to an excited singlet state and then an excited triplet state. molecular oxygen is present at its ground triplet state When the photosensitizer and an oxygen molecule are in proximity, an energy transfer can take place that allows the photosensitizer to relax to its ground singlet state, and create an excited singlet state oxygen molecule. Since singlet oxygen is highly reactive and cytotoxic, the tumour cells are destroyed. Mechanism of action
