Photosensitized Radical Mediated Lipid Peroxidation in Single Giant Unilamellar Vesicles (GUVs)

ANDRES M. DURANTINI; ISABEL BACELLAR; MAURICIO DA SILVA BAPTISTA; GONZALO COSA

Torornto

Conferencia; 100th Canadian Chemistry Conference and Exhibition; 2017

PDTis an established approach for the targeted destruction of pathologiccells and tissue. It provides a potent platform for the treatment of cancers anddrug-resistant microbes. The main mechanism of action relies on the photo-oxidationof biological membranes by oxidizing the lipids. Giventhe role of lipid photo-oxidation in PDT and other photobiological processessuch as photoaging, we sought to develop methods to study in real-time theformation of lipid peroxyl radicals in giant unilamellar vesicles (GUVs) towardgaining a mechanistic understanding of the process. In this work, we describe the use of wide fieldfluorescence microscopy jointly with a fluorogenic α-tocopherol analogue probe previouslydeveloped by us (H2B-PMHCactivated by reaction with lipid peroxyl radicals and singlet oxygen (1O2)).  This probe is able to report with incredible sensitivity and in singleGUVs membrane peroxidation with a variety of photosensitizers. Thesephotosensitizers are capable of producing free radicals by type I and type II mechanismwith different efficiencies and different degrees of binding to lipidsmembranes. Our results provide insight on how these parameters constraint lipidperoxidation.