title: AC-electric field dependent electroformation of giant lipid vesicles.
abstract: Giant vesicles of larger than 5 microm, which have been of intense interest for their potential as drug delivery vehicles and as a model system for cell membranes, can be rapidly formed from a spin-coated lipid thin film under an electric field. In this work, we explore the AC-field dependent electroformation of giant lipid vesicles in aqueous media over a wide range of AC-frequency from 1 Hz to 1 MHz and peak-to-peak field strength from 0.212 V/mm to 40 V/mm between two parallel conducting electrode surfaces. By using fluorescence microscopy, we perform in-situ microscopic observations of the structural evolution of giant vesicles formed from spin-coated lipid films under varied uniform AC-electric fields. The real-time observation of bilayer bulging from the lipid film, vesicle growth and fusing further examine the critical role of AC-induced electroosmotic flow of surrounding fluids for giant vesicle formation. A rich AC-frequency and field strength phase diagram is obtained experimentally to predict the AC-electroformation of giant unilamellar vesicles (GUVs) of l-alpha-phosphatidylcholine, where a weak dependence of vesicle size on AC-frequency is observed at low AC-field voltages, showing decreased vesicle size with a narrowed size distribution with increased AC-frequency. Formation of vesicles was shown to be constrained by an upper field strength of 10 V/mm and an upper AC-frequency of 10 kHz. Within these parameters, giant lipid vesicles were formed predominantly unilamellar and prevalent across the entire electrode surfaces.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame IN, USA.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Politano
authors.forename: Victoria E
authors.initials: VE
authors.lastname: Froude
authors.forename: Benxin
authors.initials: B
authors.lastname: Jing
authors.forename: Yingxi
authors.initials: Y
authors.lastname: Zhu
mesh_terms: D004337:Drug Carriers / Q000737:chemistry; D055664:Electrochemical Techniques / Q000379:methods*; D008051:Lipid Bilayers / Q000737:chemistry; D008055:Lipids / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D013678:Technology, Pharmaceutical / Q000379:methods*; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D004337:Drug Carriers; D008051:Lipid Bilayers; D008055:Lipids; D053835:Unilamellar Liposomes