The lifetime of singlet oxygen in cells: a pathway to increased efficacy of photodynamic therapy for cancer

Photodynamic therapy of cancer is based on the cytotoxic effect of singlet oxygen. Singlet oxygen is generated by the transfer of energy from photoactivated drug molecules (called photosensitizer) to molecular oxygen. The radius of cytotoxic activity of singlet oxygen is determined by the rate of diffusion and its lifetime. Previous research in this field has not provided a clear answer regarding the lifetime of singlet oxygen in cells. The main objective of this project is to determine the lifetime of singlet oxygen in cells and to obtain an answer to the above key issue of the mechanism of photodynamic therapy. In this project, we will monitor the quenching of phosphorescence of singlet oxygen produced by photosensitizers with excitation in the visible region of the spectrum, or by direct excitation of molecular oxygen by laser pulses at 765 nm. On the basis of the obtained results, we draw conclusions regarding the optimization of treatment processes associated with photodynamic therapy.