title: Structure and Volta potential of lipid multilayers: effect of X-ray irradiation.
abstract: The effect of hard X-ray radiation on the structure and electrostatics of solid-supported lipid multilayer membranes is investigated using a scanning Kelvin probe (SKP) integrated with a high-energy synchrotron beamline to enable in situ measurements of the membranes' local Volta potential (V(p)) during X-ray structural characterization. The undulator radiation employed does not induce any detectable structural damage, but the V(p) of both bare and lipid-modified substrates is found to undergo strong radiation-induced shifts, almost immediately after X-ray exposure. Sample regions that are macroscopically distant (~cm) from the irradiated region experience an exponential V(p) growth with a characteristic time constant of several minutes. The V(p) variations occurring upon periodic on/off X-ray beam switching are fully or partially reversible depending on the location and time-scale of the SKP measurement. The general relevance of these findings for synchrotron-based characterization of biomolecular thin films is critically reviewed.
authors.affiliation: Institute for X-ray Physics, University of Göttingen, Göttingen, Germany. sajalkg@gmail.com
authors.forename: S K
authors.initials: SK
authors.lastname: Ghosh
authors.forename: B
authors.initials: B
authors.lastname: Salgin
authors.forename: D
authors.initials: D
authors.lastname: Pontoni
authors.forename: T
authors.initials: T
authors.lastname: Reusch
authors.forename: P
authors.initials: P
authors.lastname: Keil
authors.forename: D
authors.initials: D
authors.lastname: Vogel
authors.forename: M
authors.initials: M
authors.lastname: Rohwerder
authors.forename: H
authors.initials: H
authors.lastname: Reichert
authors.forename: T
authors.initials: T
authors.lastname: Salditt
mesh_terms: D055664:Electrochemical Techniques; D008051:Lipid Bilayers / Q000737:chemistry* / Q000528:radiation effects*; D010713:Phosphatidylcholines / Q000737:chemistry*; D010718:Phosphatidylserines / Q000737:chemistry*; D017356:Synchrotrons; D014961:X-Ray Diffraction; D014965:X-Rays
chemical_list: D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D010718:Phosphatidylserines; C017251:1,2-oleoylphosphatidylcholine