LUNEX5: A French FEL Test Facility Light Source Proposal

http://accelconf.web.cern.ch/AccelConf/IPAC2012/papers/tuppp005.pdfInternational audienceLUNEX5 is a new Free Electron Laser (FEL) source project aimed at delivering short and coherent X-ray pulses to probe ultrafast phenomena at the femto-second scale, to investigate extremely low density samples as well as to image individual nm scale objects

The LUNEX5 project

http://accelconf.web.cern.ch/AccelConf/FEL2012/papers/froa03.pdfInternational audienceLUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short, intense, and coherent pulses in the soft X-ray region. The project consists of a Free Electron Laser (FEL) line enabling the most advanced seeding configurations: High order Harmonic in Gas (HHG) seeding and Echo Enable Harmonic Generation (EEHG) with in-vacuum (potentially cryogenic) undulators of 15 and 30 mm period. Two accelerator types feed this FEL line : a 400 MeV Conventional Linear Accelerator (CLA) using superconducting cavities compatible with a future upgrade towards high repetition rate, for the investigations of the advanced FEL schemes; and a 0.4 - 1 GeV Laser Wake Field Accelerator (LWFA), to be qualified in view of FEL application, in the single spike or seeded regime. Two pilot user experiments for timeresolved studies of isolated species and solid state matter dynamics will take benefit of LUNEX5 FEL radiation and provide feedback of the performance of the different schemes under real user conditions

Time-of-Flight Secondary Ion Mass Spectrometry Investigation of the Orientation of Adsorbed Antibodies on SAMs Correlated to Biorecognition Tests

The adsorption of an antiglutamate dehydrogenase (Anti-GDH) antibody on different surfaces was studied to probe its orientation and bioactivity. Three different situations were investigated: physisorption on a −COOH-terminated thiols self-assembled monolayer (SAM) on gold, covalent grafting on the same SAM using NHS-EDC activation, and physisorption on a −CH₃ SAM. The orientation of the antibody was investigated combining time-of-flight secondary ion mass spectrometry and principal component analysis. Several orientations are proposed for each case and compared to the results of biorecognition measurements with the antigen (GDH). At each step, protein layers were characterized ex-situ with polarization-modulated infrared reflection absorption spectroscopy and in situ (i.e., in the liquid phase) with quartz crystal microbalance with dissipation monitoring. Biorecognition measurements showed interesting correlations with proposed protein orientations. The role of hydrophobic and/or electrostatic interactions and that of covalent bonding are discussed to underline the influence of the orientation on the bioactivity of adsorbed Anti-GDH

Probing the Orientation of β‑Lactoglobulin on Gold Surfaces Modified by Alkyl Thiol Self-Assembled Monolayers

The adsorption of a globular protein on chemically well controlled surfaces was investigated in order to correlate its orientation to the surface properties. To this end, three different alkyl thiols, differing by their end group (−COOH, −CH₃, and −NH₂), were used to build up self-assembled monolayers (SAMs) on gold substrates. β-Lactoglobulin (βLG) was then adsorbed on these SAMs by immersion in a phosphate buffer solution. The surface modification with alkyl thiols and the subsequent adsorption of proteins were characterized <i>ex situ</i> by polarization modulated infrared reflection–absorption spectroscopy (PM-IRRAS) and X-ray photoelectron spectroscopy (XPS). The adsorption behavior of proteins was also monitored <i>in situ</i> using quartz crystal microbalance with dissipation measurements (QCM-D). Direct evidence regarding the protein orientation in the adsorbed state was obtained by means of time-of-flight secondary ion mass spectrometry (ToF-SIMS). Principal component analysis (PCA), performed on the ToF-SIMS results, enables to separate the samples and shows that the proteins display different distributions of amino acids at the surface depending on the conditioning thiol layer. Our results revealed that the adsorption mode of the protein is influenced by the thiol end groups, and specific orientations of the protein on the surface are proposed for the different substrates