title: Reactive landing of peptide ions on self-assembled monolayer surfaces: an alternative approach for covalent immobilization of peptides on surfaces.
abstract: Soft landing of mass-selected peptide ions onto reactive self-assembled monolayer surfaces (SAMs) was performed using a newly constructed ion deposition apparatus. SAM surfaces before and after soft landing were characterized ex situ using time-of-flight secondary-ion mass spectrometry (TOF-SIMS) and infrared reflection-absorption spectroscopy (IRRAS). We demonstrate that reactive landing (RL) results in efficient covalent linking of lysine-containing peptides onto the SAM of N-hydroxysuccinimidyl ester-terminated alkylthiol on gold (NHS-SAM). Systematic studies of the factors that affect the efficiency of RL revealed that the reaction takes place upon collision and is promoted by the kinetic energy of the ion. The efficiency of RL is maximized at ca. 40 eV collision energy. At high collision energies the RL efficiency decreases because of the competition with scattering of ions off the surface. The reaction yield is independent of the charge state of the projectile ions, suggesting that peptide ions undergo efficient neutralization upon collision. Chemical and physical properties of the SAM surface are also important factors that affect the outcome of RL. The presence of chemically reactive functional groups on the SAM surface significantly improves the reaction efficiency. RL of mass- and energy-selected peptide ions on surfaces provides a highly specific approach for covalent immobilization of biological molecules onto SAM surfaces.
authors.affiliation: Pacific Northwest National Laboratory, Fundamental Science Directorate, Richland, WA 99352, USA.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.forename: Omar
authors.initials: O
authors.lastname: Hadjar
authors.forename: Paul L
authors.initials: PL
authors.lastname: Gassman
authors.forename: Julia
authors.initials: J
authors.lastname: Laskin
mesh_terms: D000595:Amino Acid Sequence; D004800:Enzymes, Immobilized / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D008239:Lysine / Q000737:chemistry; D008956:Models, Chemical; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D018629:Spectrometry, Mass, Secondary Ion; D019265:Spectroscopy, Near-Infrared; D013388:Succinimides / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013499:Surface Properties
chemical_list: D004800:Enzymes, Immobilized; D007477:Ions; D010455:Peptides; D013388:Succinimides; D013438:Sulfhydryl Compounds; D006046:Gold; D008239:Lysine; C001426:N-hydroxysuccinimide