title: Probing proteins on functionalized silicon surfaces using matrix-assisted laser desorption/ionization mass spectrometry.
abstract: Flat H-terminated Si(111) substrates modified with alkyl monolayers terminated with hydrophobic and hydrophilic functional groups were prepared using known surface functionalization methods and characterized by FTIR, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The surfaces were then used for the study of non-specific binding of proteins from complex mixtures (using standard mixture of proteins with average molecular weight approximately 6-66 kDa) by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Protein adsorption on these surfaces (following on-probe fractionation of the mixture) was found to be dependent on the nature of surface functional groups, and nature and pH of rinsing solutions used. The results obtained in this work demonstrate that simple silicon-based surface modifications can be effective for direct analysis of complex mixtures by MALDI-MS. Preliminary results obtained using similarly functionalized porous silicon substrates proved that such substrates are (due to their increased surface areas) better performing than flat silicon.
authors.affiliation: Department of Chemistry, York University, 4700 Keele Street, Toronto, Ont. M3J 1P3, Canada.
authors.forename: Tadesse Z
authors.initials: TZ
authors.lastname: Mengistu
authors.forename: Leroi
authors.initials: L
authors.lastname: DeSouza
authors.forename: Sylvie
authors.initials: S
authors.lastname: Morin
mesh_terms: D000327:Adsorption; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force; D015335:Molecular Probes; D008970:Molecular Weight; D011506:Proteins / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D015335:Molecular Probes; D011506:Proteins; D012825:Silicon