Direct imaging of singlet oxygen luminescence in photodynamic therapy

Abstract

s / Photodiagnosis and Photodynamic Therapy 12 (2015) 325–375 341 Quantum dot-sensitiser conjugates for two-photon excited photodynamic therapy Colin Fowley, Anthony P. McHale, Bridgeen McCaughan, Aurore Fraix, Salvatore Sortino, John F. Callan School of Pharmacy, Ulster University, Northern Ireland, United Kingdom Currently approved photosensitisers (PS) absorb light in the visible region of the electromagnetic spectrum, well below the wavelengths where light has maximum penetration through human tissue (i.e. 750–900nm). As a result, significant effort has been devoted to developing sensitisers that absorb in or close to this region. Adopting an alternative approach conventional sensitisers are indirectly excited by longer wavelength light through an energy transfer (FRET) process. Carbon Quantum Dots (CQDs) are a relatively new class of fluorescent nanoparticle have two-photon excitation (TPE) absorption cross-sections some three orders of magnitudes greater than organic dye based sesnitisers. By covalently attaching the CQDs to a conventional sensitiser the latter is indirectly excited upon TPE of the CQD at 800nm. Specifically, we have prepared a CQD-PPIX conjugate and demonstrated its ability to significantly reduce the viability of cancer cells in vitro and tumour volume in vivo upon TPE. Furthermore, we have prepared a CQD-nitroaniline conjugate allowing production of the cytotoxic NO radical upon TPE of the CQD at 800nm and demonstrated this conjugates cytotoxic potential in vitro and in vivo. The production of NO radical is an oxygen independent process, and may improve the potential of this technique in hypoxic environments. http://dx.doi.org/10.1016/j.pdpdt.2015.07.066 Roadmap toward the standardization of photodynamic therapy for port wine stains Xiaoming Hu, Feng Juan Zhang School of Life Science, Beijing Institute of Technology, China Photodynamic therapy (PDT) has demonstrated its safety and effectiveness in dermatology. However, large-scale prospective, comparative, and controlled clinical studies are still required to better understand the complex relation between treatment outcomeand lightparameters aswell as to standardizePDTprocedures worldwide. With the proposed digital illumination instrument, an approach toward the standardization of port wine stains is introduced in this paper. A 3D patient model is reconstructed in the preoperative period, and the lesion point clouds are further rated into different levels with a superpixel algorithm according to their color and distance. The optimized treatment direction and dose can be adjusted in each small patch with the same disease rated by the doctor. In the intraoperative period, the light source for treatment can be synchronized with the blood oxygen saturation, and the response during the treatment and dose adjustment are recorded for subsequent study. The actual dose in each patch is accumulated in the postoperative period, and the outcome is analyzed and compared with that of the previous 3D lesion model. Hence, an optimized treatment plan can be proposed individually in the succeeding treatment session, and a comparative and controlled statistical analysis can be performed. http://dx.doi.org/10.1016/j.pdpdt.2015.07.067 Direct imaging of singlet oxygen luminescence in photodynamic therapy