Developing cationic liposomes as carriers for photosensitizers

GONZÁLEZ GRAGLIA, MARÍA ANTONELLA; M. T. BAUMGARTNER; PRUCCA, CÉSAR G.; MIRETTI, MARIANA

Córdoba

Congreso; LI Reunión Anual de la Sociedad Argentina de Biofísica; 2023

Sociedad Argentina de Biofísica

Photodynamic therapy (PDT) is a therapeutic alternative to treat several pathologies from microbial infections to cancers. PDT consists of applying a photosensitizer (PS) that interacts with light in an appropriate wavelength, absorbing its energy and going from the basal to the excited singlet state. This excited state can experience intersystem crossing to the excited triplet state (3PS*). 3PS* can generate reactive oxygen species that induce injury and cellular death.Among more studied PS, phthalocyanines (Pcs) are second-generation photosensitizers that absorb light at 670 nm, have a long triplet lifetime, and generate singlet oxygen efficiently. The main inconvenience with this kind of PS is its hydrophobic nature, which limits its intravenous application. Here is where the use of a transporter for the Pc becomes an interesting strategy, being liposomes (LP) one of the most widely known and studied carriers. LP are biocompatible and biodegradable and they are composed of phospholipids. The present work aims to design cationic liposomes containing Zn-phthalocyanine, to increase the interactions between charged liposomes and cells or pathogens that exhibit anionic surfaces. To accomplish this purpose, liposomes composed of DOTAP (dioleoyl-3-trimethylammonium propane), DPPC and cholesterol were prepared at different ratios. For each composition, three ZnPc concentrations were tested: 0 μM, 5 μM and 20 μM. Photophysical properties such as light absorption and fluorescence emission, size and zeta potential were measured for each formulation.Size was measured for each formulation at 0, 7, 14, 21 and 28 days, considering day 0 as the preparation day. All compositions exhibited an increase over time, being the composition with cholesterol the most stable for all ZnPc concentrations.AgradecimientosM.A.G.G. thanks Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) for her fellowship. This work was supported by Secretaría de Ciencia y Tecnología, Universidad Nacional de Córdoba (SeCyT), and Fondo para la Investigación Científica y Tecnológica (FONCYT).