title: The dynamics of giant unilamellar vesicle oxidation probed by morphological transitions.
abstract: We have studied the dynamics of Lissamine Rhodamine B dye sensitization-induced oxidation of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) giant unilamellar vesicles (GUVs), where the progression of the underlying chemical processes was followed via vesicle membrane area changes. The surface-area-to-volume ratio of our spherical GUVs increased after as little as ten seconds of irradiation. The membrane area expansion was coupled with high amplitude fluctuations not typical of GUVs in isoosmotic conditions. To accurately measure the area of deformed and fluctuating membranes, we utilized a dual-beam optical trap (DBOT) to stretch GUV membranes into a geometrically regular shape. Further oxidation led to vesicle contraction, and the GUVs became tense, with micron-scale pores forming in the bilayer. We analyzed the GUV morphological behaviors as two consecutive rate-limiting steps. We also considered the effects of altering DOPC and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-(lissamine rhodamine B sulfonyl) (RhDPPE) concentrations. The resulting kinetic model allows us to measure how lipid molecular area changes during oxidation, as well as to determine the rate constants controlling how quickly oxidation products are formed. Controlled membrane oxidation leading to permeabilization is also a potential tool for drug delivery based on engineered photosensitizer-containing lipid vesicles.
authors.affiliation: Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1211, USA.
authors.forename: Shalene
authors.initials: S
authors.lastname: Sankhagowit
authors.affiliation: Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089-2560, USA.
authors.forename: Shao-Hua
authors.initials: SH
authors.lastname: Wu
authors.affiliation: Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089-2560, USA.
authors.forename: Roshni
authors.initials: R
authors.lastname: Biswas
authors.affiliation: Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1211, USA.
authors.forename: Carson T
authors.initials: CT
authors.lastname: Riche
authors.affiliation: Ming Hsieh Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90089-2560, USA.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Povinelli
authors.affiliation: Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1211, USA. Electronic address: malmstad@usc.edu.
authors.forename: Noah
authors.initials: N
authors.lastname: Malmstadt
mesh_terms: D007700:Kinetics; D008567:Membranes, Artificial; D010084:Oxidation-Reduction; D010713:Phosphatidylcholines / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D010713:Phosphatidylcholines; D012235:Rhodamines; C022027:lissamine rhodamine B; C017251:1,2-oleoylphosphatidylcholine
keywords: Giant unilamellar vesicle; Lipid oxidation; Lipid peroxidation; Membrane pore; Oxidation kinetic; Phospholipid tail scission