Pedersen, Brian Wett6; Breitenbach, Thomas7; Redmond, Robert W.5; Ogilby, Peter Remsen7
1 Interdisciplinary Nanoscience Center, Faculty of Science, Aarhus University, Aarhus University2 Department of Chemistry, Faculty of Science, Aarhus University, Aarhus University3 Department of Biomedicine - Forskning og uddannelse, Syd, Department of Biomedicine, Health, Aarhus University4 Department of Chemistry, Science and Technology, Aarhus University5 unknown6 Department of Biomedicine - Forskning og uddannelse, Syd, Department of Biomedicine, Health, Aarhus University7 Department of Chemistry, Science and Technology, Aarhus University
The response of a given cell to spatially-resolved sub-cellular irradiation of a singlet oxygen photosensitizer (protoporphyrin IX, PpIX) using a focused laser was assessed. In these experiments, incident light was scattered over a volume greater than that defi ned by the dimensions of the laser beam as a consequence of the inherent inhomogeneity of the cell. Upon irradiation at a wavelength readily absorbed by PpIX in a one-photon transition, this scattering of light eliminated any advantage accrued to the use of focused irradiation. However, upon irradiation at a longer wavelength where PpIX can only absorb light under non-linear two-photon conditions, meaningful intracellular resolution was achieved in the small spatial domain where the light intensity was high enough for absorption to occur.