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Fluorescence Anisotropy Imaging Reveals Localization of meso ‐Tetrahydroxyphenyl Chlorin in the Nuclear Envelope
Author(s) -
Foster Thomas H.,
Pearson Benjamin D.,
Mitra Soumya,
Bigelow Chad E.
Publication year - 2005
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/2005-08-11-rn-646
Subject(s) - anisotropy , fluorescence anisotropy , fluorescence , polarization (electrochemistry) , confocal , chemistry , dipole , molecular physics , photosensitizer , photochemistry , monolayer , photodynamic therapy , biophysics , materials science , nuclear magnetic resonance , optics , physics , organic chemistry , biology , biochemistry
We have measured the intrinsic fluorescence anisotropies of six photosensitizers in homogeneous solution, and we have imaged the anisotropies of these sensitizers in tumor cell monolayers using polarization‐sensitive laser‐scanning confocal microscopy. The intrinsic anisotropies are unremarkable and are within the approximate range of 0.2–0.27. In cells, however, very interesting behavior is exhibited by meso ‐tetrahydroxyphenyl chlorin (mTHPC). Polarization‐sensitive images of mTHPC's fluorescence show a pronounced banding of alternating high and low anisotropy consistent with an ordering of the sensitizer in the nuclear envelope, indicating that this structure is a target of photodynamic damage with this sensitizer. None of the other sensitizers exhibits localization to the nuclear envelope. The frequency distributions of the intracellular anisotropies of the sensitizers exhibit variable peaks and widths. An unusual case is that of Photofrin, with a peak in its anisotropy frequency distribution of –0.12. The change from a positive intrinsic anisotropy in homogeneous solution to a negative value in cells suggests an environmentally induced change in the relative orientations of the absorption and emission dipole moments.