Photodynamic therapy (PDT)
Photodynamic therapy (PDT) is a broadly used technique for killing diseased cells by incorporating a combination of light and a light-activated drug, known as a photosensitizer (PS). In general, the singlet excited state of the PS formed upon absorption of light undergoes intersystem crossing to a populate triplet excited state. This transfers energy to ground-state triplet molecular oxygen (3O2) generating singlet oxygen (1O2). Singlet oxygen is extremely reactive and toxic; under physiological conditions it only diffuses a distance of about 2 μm before reacting or relaxing to its ground state. Thus biomolecules in solution are oxidized if they react with singlet oxygen before it deactivates. These processes are summarized below.
 Photo of PDT treatment (left) and energetic showing photosensitization of singlet oxygen (right). |
PDT is currently used to treat a wide range of diseases characterized by neoplastic growth, such as various cancers, actinic keratosis and age-related macular degeneration. In the absence of light the PS compounds are benign, thus systemic toxicity is rare and treatment may be repeated without acquiring resistance.
My research in this field is particularly aimed at:
- heavy-atom-free photosensitizers which are less toxic and expensive compared to conventional ones
- molecules capable of binding and slow thermal release of singlet oxygen for combined PDT/photothermal treatments
- singlet oxygen sensing and bioimaging