Visualising the intracellular environment during normal cell function and photodynamic therapy using advanced imaging techniques

Photodynamic Therapy (PDT) is an established method to treat the variety of cancers (particularly lung, head, neck and non-melanoma skin cancer) and for treating the disease known as acute macular degeneration (AMD) which is a main source of legal blindness in old people. It is based on the light activation of the sensitizer molecules preferentially localised in the cancerous tissues, which produce cytotoxic species such as singlet oxygen, which kill surrounding cells in the target areas. For full understanding of PDT mechanism it is crucial to be able to visualise the localisation of both the sensitiser and cytotoxic species within cells. This proposal seeks to use advanced imaging techniques, the combination of fluorescence, Raman and second harmonic generation imaging to visualise individual intracellular events during normal cell function and PDT-induced cell death. We will take advantage of high two-photon absorption (TPA) cross sections of conjugated porphyrin dimers for TPA PDT and TPA intracellular imaging for high image resolution, deeper tissue penetration and precise application of light for the benefit of treatments of diseases such as AMD, where out of focus damage should be minimised. Series of sensitisers would be screened for photophysical properties, cell localisation and PDT action in vitro to reveal the best candidates for in vivo testing. We will combine imaging results for the sensitisers with that of singlet oxygen, the cytotoxic species responsible for cell death, which would provide us with the insight of the PDT mechanism in cellulo. This is an interdisciplinary project involving molecular design, synthesis, photophysics, photochemistry, imaging, spectroscopy and cell biology.