title: Engineering matrix-free laser desorption ionization mass spectrometry using glancing angle deposition films.
abstract: BACKGROUND
  Thin, nanoporous films fabricated using Glancing Angle Deposition (GLAD) technology are demonstrated for solid matrix laser desorption/ionization mass spectrometry (SMALDI-MS). GLAD allows facile engineering of nanoporosity, film thickness, post alignment, and material composition, as demonstrated here by the fabrication of Co-GLAD and Si-GLAD films for SMALDI, and by exploration of the SMALDI performance as a function of thickness, post density, and angle of the post relative to surface normal.
  
  
  METHODS
  GLAD films were prepared by electron beam evaporation onto silicon substrates, using steep angles of incidence for the vacuum deposition, with computer controlled substrate rotation. LDI from the GLAD films was evaluated using an MDS-Sciex time-of-flight (TOF) MALDI mass spectrometer.
  
  
  RESULTS
  Co-GLAD films give a limit of quantitation of 6 fmol for complex carbohydrate derivatives, and slanted-post Si-GLAD films show up to three times higher sensitivity than vertical post structures. Reproducibility of both Si and Co films is much higher than conventional MALDI methods for m/z below at least 2100 Da. Both reproducibility and detection limits are comparable to or better than other nano-structured materials. Co-GLAD films are significantly better in performance than Co powders or Co thin films on silicon substrates previously evaluated.
  
  
  CONCLUSIONS
  The flexibility of GLAD for thin film fabrication of LDI materials is demonstrated by the range of nanoporous materials that can be grown, and the fine control over structural conformation, thickness and porosity. Copyright © 2017 John Wiley & Sons, Ltd.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, AB, Canada, T6G 2G2.
authors.forename: Reshma
authors.initials: R
authors.lastname: Singh
authors.affiliation: Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada, T6G 2V4.
authors.forename: Louis W
authors.initials: LW
authors.lastname: Bezuidenhout
authors.affiliation: National Institute for Nanotechnology, National Research Council Canada, Edmonton, AB, Canada, T6G 2M9.
authors.forename: Abebaw
authors.initials: A
authors.lastname: Jemere
authors.affiliation: Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada, T6G 2V4.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada, T6G 2V4.|National Institute for Nanotechnology, National Research Council Canada, Edmonton, AB, Canada, T6G 2M9.
authors.forename: Michael
authors.initials: M
authors.lastname: Brett
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, AB, Canada, T6G 2G2.|National Institute for Nanotechnology, National Research Council Canada, Edmonton, AB, Canada, T6G 2M9.
authors.forename: D Jed
authors.initials: DJ
authors.lastname: Harrison