Developing cationic liposomes as carriers for photosensitizers.

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

Congreso; LI Reunión Anual Sociedad Argentina de Biofisica; 2023

Photodynamic therapy (PDT) is a therapeutic alternative to treat several pathologies frommicrobial infections to cancers. PDT consists of applying a photosensitizer (PS) thatinteracts with light in an appropriate wavelength, absorbing its energy and going fromthe basal to the excited singlet state. This excited state can experience intersystemcrossing to the excited triplet state (3PS*). 3PS* can generate reactive oxygen species thatinduce injury and cellular death.Among more studied PS, phthalocyanines (Pcs) are second-generation photosensitizersthat absorb light at 670 nm, have a long triplet lifetime, and generate singlet oxygenefficiently. The main inconvenience with this kind of PS is its hydrophobic nature, whichlimits its intravenous application. Here is where the use of a transporter for the Pcbecomes an interesting strategy, being liposomes (LP) one of the most widely known andstudied carriers. LP are biocompatible and biodegradable and they are composed ofphospholipids.The present work aims to design cationic liposomes containing Zn-phthalocyanine, toincrease the interactions between charged liposomes and cells or pathogens that exhibitanionic surfaces. To accomplish this purpose, liposomes composed of DOTAP (dioleoyl-3-trimethylammonium propane), DPPC and cholesterol were prepared at different ratios. Foreach composition, three ZnPc concentrations were tested: 0 μM, 5 μM and 20 μM.Photophysical properties such as light absorption and fluorescence emission, size and zetapotential were measured for each formulation.Size was measured for each formulation at 0, 7, 14, 21 and 28 days, considering day 0 asthe preparation day. All compositions exhibited an increase over time, being thecomposition with cholesterol the most stable for all ZnPc concentrations.