Evaluation of cholesterol effect in DPPC liposome-phthalocyanine interaction

GONZÁLEZ M A; GOROD N S; BORIONI J L; TEMPESTI T C; PUIATTI M.; MIRETTI M.

Jornada; LatinXChem22; 2022

LatinXChem22

Phthalocyanines (Pcs) and their derivatives have been considered excellent photosensitizers for photodynamic therapy.[1] Most Pcs are aromatic and lipophilic with a lack solubility in aqueous media, which results in a significant limiting factor in their intravenous administration. To improve solubility, Pcs have been incorporated into several delivery systems, such as liposomes (LP), micelles, and nanoparticles. Several studies using liposomes as carriers for Pcs were reported in the last years.[2] Due to lipophilic nature, Pcs molecules can be entrapped into lipophilic chains in the phospholipid bilayer, decreasing aggregation and, consequently, increasing their photody- namic efficiency [3]. In this work, we evaluated the behavior of two Pcs, Zn(II)phthalocyanine, and a tetra-aminoderivative (TaZnPc) in lipid membranes of DPPC and different cholesterol (chol) rates. Four liposome formulations were prepared with DPPC with 0, 30, and 45% chol. The incorporation of Pcs into liposomes was evaluated by fluorescence spectroscopy at different times. The results show that ZnPc is incorporated in the hydrophobic region of liposomes in all formulations evaluated. In the same way, the behavior of TAZnPc for DPPC liposomes was similar to those obtained with ZnPc, showing the incorporation into the phospholipid bilayer. However, for membranes with chol, in all rates evaluated, TAZnPc did not show incorporation into the bilayer. Also, was simulated this interaction with molecular dynamics. It was observed the same behavior as in experimental trials. In conclusion, ZnPc interacts with all membranes evaluated, but the presence of chol did affect the internalization of TAZnPc.