title: Comparison of photosensitizer (AIPcS2) quantification techniques: in situ fluorescence microsampling versus tissue chemical extraction.
abstract: A noninvasive in situ fluorescence-based method for the quantification of the photosensitizer chloroaluminum disulfonated phthalocyanine was compared to the highly accurate but nonreal time ex vivo spectrofluorometry method. Our in vivo fluorescence technique is designed to allow real-time assessment of photosensitizer in tumor and normal tissues and therefore temporally optimal light delivery. Laser-induced fluorescence was used to measure photosensitizer concentration from multiple microscopic regions of tissue. Ex vivo chemical extraction was used to quantify photosensitizer concentration in the same volume of tissue. The amount of photosensitizer in the vascular and/or parenchymal compartments of skeletal muscle and liver was determined by quantifying fluorescent signal in vivo, ex vivo and after blood removal. Confocal microscopy was used to spatially document photosensitizer localization 30 min and 24 h after delivery. While a linear correlation can exist between the fluorescence intensity measured by our fiber-optic bundle system and actual tissue concentration, temporal changes to this calibration line exist as the photosensitizer changes its partitioning fraction between the blood (vasculature) and the tissue parenchyma. In situ photosensitizer fluorescence microsampling (dosimetry) systems can be performed in real time and linearly correlated to actual tissue concentration with minimal intertissue variance. Tissue-specific differences may require temporal alterations in the calibration.
authors.affiliation: Department of Surgery, Dartmouth-Hitchcock Medical Center, One Medical Center Drive, Lebanon, NH 03756, USA.
authors.forename: C C
authors.initials: CC
authors.lastname: Lee
authors.forename: B W
authors.initials: BW
authors.lastname: Pouge
authors.forename: R R
authors.initials: RR
authors.lastname: Strawbridge
authors.forename: K L
authors.initials: KL
authors.lastname: Moodie
authors.forename: L R
authors.initials: LR
authors.lastname: Bartholomew
authors.forename: G C
authors.initials: GC
authors.lastname: Burke
authors.forename: P J
authors.initials: PJ
authors.lastname: Hoopes
mesh_terms: D000818:Animals; D005260:Female; D008099:Liver / Q000737:chemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence / Q000379:methods*; D009942:Organometallic Compounds / Q000032:analysis*; D010777:Photochemistry; D017319:Photosensitizing Agents / Q000032:analysis*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D014018:Tissue Distribution
chemical_list: D009942:Organometallic Compounds; D017319:Photosensitizing Agents; C439084:chloroaluminum disulfonated phthalocyanine