DEVELOPMENT AND EVALUATION OF ZINC PHTHALOCYANINE LOADED PCL NANOPARTICLES FOR PHOTODYNAMIC THERAPY USE

TF06

Soares, MV

Ramos-Junior, PRS

Oliveira, MR

Ricci-Junior, E

Laboratório de Desenvolvimento Galênico, Departamento de Medicamentos, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro.

Nanocarriers as polymeric nanoparticles (Nps) have been used to overcome drugs insolubility problems and improve bioavailability and target. Zinc phthalocyanine (ZnPc) is a second generation of photosensitizer used in cancer photodynamic therapy. However, it is hydrophobic and insoluble in acceptable physiologically solvents. The objective of this work is the development and characterization of poly-ε-caprolactone (PCL) nanoparticles to load ZnPc for photodynamic therapy use. Nps were prepared using nanoprecipitation method. Nanoprecipitation involves the dispersion of the polymer and the photosensitizer in acetone, which is added into an aqueous phase containing a surfactant under moderate stirring. The acetone was removed by evaporation under reduced pressure and the suspension of Nps was centrifugated and freeze-dried. Nps were prepared with different amounts of polymer, surfactant, organic solvent and aqueous phase to modify the particle size. Size distribution and morphology were analyzed by laser light scattering and transmission electron microscopy (TEM). Encapsulation efficiency was determined by a fluorescence emission method. The fluorescence emission intensity was correlated with the ZnPc concentration in acetone (μg/ml) to obtain the standard curve. The standard solutions were excited at 602 nm and the fluorescence emission spectra recorded between 630 to 730 nm using a spectrofluorimeter. ZnPc standard solution and ZnPc loaded Nps were also analyzed for fluorescence emission for spectroscopic characterization. The smallest nanoparticles were obtained from two samples prepared in triplicate containing 50 mg (A) or 100 mg PCL (B), 25 ml acetone, 0.3 mg ZnPc and 50 ml aqueous phase (1% surfactant). The Nps have a mean diameter of 259.1 ± 2.1 nm (A) and 341.2 ± 4.5 nm (B), a narrow size distribution with a polydispersive index of 0.11 ± 0.03 (A) and 0.11 ± 0.02 (B), smooth surface and spherical shape. The process yield was 33.5 ± 1.8% (A) and 62.3 ± 4.5% (B). The intensity of fluorescence emission of ZnPc correlated linearly with the concentration over the 0.02 – 0.1 μg/ml ZnPc range. The precision of the standard curve was below 5%. The correlation coefficient was 0.9999, with excellent linearity. The encapsulation efficiency was 45 ± 3.7% (A) and 57 ± 1.9% (B). ZnPc loaded Nps maintains its spectroscopic behavior after encapsulation. Nanoprecipitation is an adequate method to encapsulate ZnPc in PCL particles with nanometric size and satisfactory encapsulation efficiency.