Redistribution of Foscan from plasma proteins to model membranes

Photodynamic therapy is a comparatively novel modality of tumours treatment that includes simultaneous action of photosensitizers, light and oxygen. Photosensitizer redistribution between plasma proteins and biomembranes define photosensitizers interaction with cells, their intracellular localizatio...

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Bibliographic Details
Published in:Photochemical & photobiological sciences 2006-08, Vol.5 (8), p.770-777
Main Authors: Sasnouski, Siarhei, Kachatkou, Dzmitry, Zorin, Vladimir, Guillemin, François, Bezdetnaya, Lina
Format: Article
Language:English
Subjects:
Binding Sites
Biochemistry, Molecular Biology
Biophysics
Blood Proteins - chemistry
Cholesterol, HDL - chemistry
Fluorescence Resonance Energy Transfer - methods
Kinetics
Life Sciences
Lipids - chemistry
Membranes, Artificial
Mesoporphyrins - chemistry
Models, Molecular
Photosensitizing Agents - chemistry
Sensitivity and Specificity
Thermodynamics
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Summary:Photodynamic therapy is a comparatively novel modality of tumours treatment that includes simultaneous action of photosensitizers, light and oxygen. Photosensitizer redistribution between plasma proteins and biomembranes define photosensitizers interaction with cells, their intracellular localization and kinetics of sensitizers accumulation in the tumour. Present study investigates the kinetics of Foscan release from plasma proteins to model membranes using fluorescence resonance energy transfer (FRET) from label, covalently bound to protein, to sensitizer. We have demonstrated very slow kinetics of Foscan release from protein complexes with rate constants of (1.7 +/- 0.1) x 10(-3) s(-1) for albumin and (1.6 +/- 0.3) x 10(-4) s(-1) for high-density lipoproteins (HDL). Foscan redistributes by both collision and diffusion-mediated transfer from complexes with HDL, with bimolecular rate constant k(out) = (8.8 +/- 1.4) x 10(-2) M(-1) s(-1). Thermodynamic considerations proposed that sensitizer release from HDL into the aqueous medium is unfavourable and collision mechanism appeared to be a preferred mode of transfer in biological environment. Slow rates of Foscan redistribution from plasma proteins should be considered while planning dosimetry protocol of Foscan-PDT.
ISSN:1474-905X
1474-9092
DOI:10.1039/b603840a