Photophysical properties of microencapsulated phthalocyanines.

VIRGINIA DIZ, GABRIELA A. GAUNA, CRISTIAN A. STRASSERT, JOSEFINA AWRUCH,LELIA E. DICELIO.

Moscú, Rusia

Congreso; Fifth International Conference on Porphyrins and Phthalocyanines (ICPP-5).; 2008

Sociedad de Porfirinas y Ftalocianinas

Nanoparticle systems such as nanocapsules, nanospheres, liposomes, Au or Ag nanoparticles and polymeric nanoparticles, present potential applications for the administration of therapeutic molecules. The aim of this project is to study  the physicochemical characterization of these drug carriers in terms of particle size distribution, morphology,  polymer molecular weight, and surface charge.  The photophysical properties of the sensitizers in association with aggregation results were evaluated in order to apply these systems for photobiological purposes.  Novel zinc (II)  phthalocyanines with different lipophilicity: 2,3,9,10,16,17,23,24-octakis[(N,N-dimethylaminoethylsulfanyl)]phthalocyaninatozinc(II) (S1), tetrakis(N,N-dibutylaminoethoxy)phth-alocyaninatozinc(II) (B), and  2,3,9,10,16,17,23,24-octakis[(N,N,N-trimethylamonium)ethylsulfanyl]phthaloc-yaninatozinc(II) octaiodide (S2 ) were incorporated into liposomes and in homogeneous media  in order to analyze their photophysical characteristics. S1 and B zinc (II) phthalocyanines were loaded in liposomes of soybean phosphatidylcholine (0.015 M),1 resulting 100 nm mean size vesicles whereas S2 was incorporated into sodium polymethacrilate (PMA). The absorption spectra of S1 and B in THF show a Q band at lmax 705 nm and 675 nm respectively2 whereas S2 in water shows two bands  at 657.5 nm  and 699 nm corresponding to the dimer and the monomer. The addition of PMA induces monomerization of S2 up to a concentration of [PMA] = 1.0 x 10-7 M. The increase in  PMA concentration does not change monomer – dimer relationship. The fluorescence quantum yield (FF) and singlet molecular oxygen quantum yield (FD) for S1 and B were performed at dye concentrations of  5.6 x10-6 M  in THF and liposomes.  THF values of FF are 0.26 and 0.23 for S1 and B respectively, and FD is 0.69 for both dyes. The fluorescence quantum yields of S2 in H2O and in PMA are in all cases lower than 10-3. Photophysical properties of S1 in liposomes do not differ from those obtained with THF, B is not incorporated into liposomes. Further photophysical studies are in progress.