UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2011 Meeting


Section: Optics, Spectroscopy, Plasma and Lasers


Title:
Time-resolved phosphorescence spectroscopy to measure the photodynamic efficiency of some phthalocyanine sensitizers


Authors:
M.L. Pascu, A. Staicu, A. Pascu, M. Boni


Affiliation:
National Institute for Lasers, Plasma and Radiation Physics Bucharest, Laser Department, Atomistilor 409, 077125 Magurele, Bucharest, Romania


E-mail
alex.pascu@inflpr.ro


Keywords:
time-resolved phosphorescence spectroscopy, phthalocyanine


Abstract:
The presentation will contain the following main aspects: Photodynamic therapy - what is it, how it works. The three elements requested: sensitizer - oxygen - light. The key element of the therapy: the photo-activated sensitizer. Phthalocyanines (macrocyclic compounds) are already of a second generation type of sensitizers for photodynamic therapy. Our focus was on metallated phthalocyanines with diamagnetic metals in the middle of their macrocycle (Zn, Cu etc). Generation of active species: the sequence of elementary molecular and intermolecular processes triggered from the absorption of a photon, to the emergence of reactive species. The special significance of the triplet state in generating active species. Main active species in PDT - the oxygen molecule in its singlet excited state. Quantum yield of the active species singlet oxygen. Measuring the population of oxygen molecules in its singlet state - chemical methods, physical methods. The spectroscopic method of the measurement of the phosphorescence intensity of the molecule of oxygen in its singlet state (λ = 1270 nm) - the most direct, specific, and which can be time-resolved. The experimental measurement setup: (i) the subassembly for laser induced generation of oxygen singlet by phthalocyanine sensitizers. Laser: pulsed YAG-Nd laser frequency doubled, tripled or quadrupled; 6 nanoseconds FWHM pulse width; pulse energy 300 mJ @ 532 nm, 180 mJ @ 355 nm, 100 mJ @ 266 nm. (ii) (ii) the subassembly for time-resolved detection of the phosphorescence of the singlet oxygen and data processing. Key element: cooled photomultiplier sensitive @ 1270 nm. Data collection with digital oscilloscope. Data obtained in measurements of (i) the quantum yields and (ii) the life-time of the population of oxygen molecules in the singlet state generated by photoactivated diamagnetic-metallated phthalocyanines in organic solvent.