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Walz A, Stoiber K, Huettig A, Schlichting H, Barth JV. Navigate Flying Molecular Elephants Safely to the Ground: Mass-Selective Soft Landing up to the Mega-Dalton Range by Electrospray Controlled Ion-Beam Deposition. Anal Chem 2022; 94:7767-7778. [PMID: 35609119 PMCID: PMC9178560 DOI: 10.1021/acs.analchem.1c04495] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The prototype of a highly versatile and efficient preparative mass spectrometry system used for the deposition of molecules in ultrahigh vacuum (UHV) is presented, along with encouraging performance data obtained using four model species that are thermolabile or not sublimable. The test panel comprises two small organic compounds, a small and very large protein, and a large DNA species covering a 4-log mass range up to 1.7 MDa as part of a broad spectrum of analyte species evaluated to date. Three designs of innovative ion guides, a novel digital mass-selective quadrupole (dQMF), and a standard electrospray ionization (ESI) source are combined to an integrated device, abbreviated electrospray controlled ion-beam deposition (ES-CIBD). Full control is achieved by (i) the square-wave-driven radiofrequency (RF) ion guides with steadily tunable frequencies, including a dQMF allowing for investigation, purification, and deposition of a virtually unlimited m/z range, (ii) the adjustable landing energy of ions down to ∼2 eV/z enabling integrity-preserving soft landing, (iii) the deposition in UHV with high ion beam intensity (up to 3 nA) limiting contaminations and deposition time, and (iv) direct coverage control via the deposited charge. The maximum resolution of R = 650 and overall efficiency up to Ttotal = 4.4% calculated from the solution to UHV deposition are advantageous, whereby the latter can be further enhanced by optimizing ionization performance. In the setup presented, a scanning tunneling microscope (STM) is attached for in situ UHV investigations of deposited species, demonstrating a selective, structure-preserving process and atomically clean layers.
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Affiliation(s)
- Andreas Walz
- Physics Department E20, Technical University of Munich, 85748 Garching, Germany
| | - Karolina Stoiber
- Physics Department E20, Technical University of Munich, 85748 Garching, Germany
| | - Annette Huettig
- Physics Department E20, Technical University of Munich, 85748 Garching, Germany
| | - Hartmut Schlichting
- Physics Department E20, Technical University of Munich, 85748 Garching, Germany
| | - Johannes V Barth
- Physics Department E20, Technical University of Munich, 85748 Garching, Germany
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Su P, Chen X, Smith AJ, Espenship MF, Samayoa Oviedo HY, Wilson SM, Gholipour-Ranjbar H, Larriba-Andaluz C, Laskin J. Multiplexing of Electrospray Ionization Sources Using Orthogonal Injection into an Electrodynamic Ion Funnel. Anal Chem 2021; 93:11576-11584. [PMID: 34378383 DOI: 10.1021/acs.analchem.1c02092] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this contribution, we report an efficient approach to multiplex electrospray ionization (ESI) sources for applications in analytical and preparative mass spectrometry. This is achieved using up to four orthogonal injection inlets implemented on the opposite sides of an electrodynamic ion funnel interface. We demonstrate that both the total ion current transmitted through the mass spectrometer and the signal-to-noise ratio increase by 3.8-fold using four inlets compared to one inlet. The performance of the new multiplexing approach was examined using different classes of analytes covering a broad range of mass and ionic charge. A deposition rate of >10 μg of mass-selected ions per day may be achieved by using the multiplexed sources coupled to preparative mass spectrometry. The almost proportional increase in the ion current with the number of ESI inlets observed experimentally is confirmed using gas flow and ion trajectory simulations. The simulations demonstrate a pronounced effect of gas dynamics on the ion trajectories in the ion funnel, indicating that the efficiency of multiplexing strongly depends on gas velocity field. The study presented herein opens up exciting opportunities for the development of bright ion sources, which will advance both analytical and preparative mass spectrometry applications.
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Affiliation(s)
- Pei Su
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Xi Chen
- Department of Mechanical and Energy Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Andrew J Smith
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Michael F Espenship
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Hugo Y Samayoa Oviedo
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Solita M Wilson
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Habib Gholipour-Ranjbar
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Carlos Larriba-Andaluz
- Department of Mechanical and Energy Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Julia Laskin
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
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Affiliation(s)
- Pei Su
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Hang Hu
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Jonas Warneke
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
- Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Universität Leipzig, Linnestr. 2, 04103 Leipzig, Germany
| | | | - Gordon A. Anderson
- GAA Custom Engineering, LLC, POB 335, Benton City, Washington 99320, United States
| | - Julia Laskin
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
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Gu M, Yang L, Hase WL, Sun J, Zhang J. Energy Transfer of Peptide Ions Colliding with a Self‐Assembled Monolayer Surface. The Influence of Peptide Ion Size. CHINESE J CHEM 2019. [DOI: 10.1002/cjoc.201800544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Meng Gu
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology Harbin Heilongjiang 150001 China
| | - Li Yang
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology Harbin Heilongjiang 150001 China
| | - William L Hase
- Department of Chemistry and BiochemistryTexas Tech University Lubbock TX 79401 USA
| | - Jianmin Sun
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology Harbin Heilongjiang 150001 China
| | - Jiaxu Zhang
- MIIT Key Laboratory of Critical Materials Technology for New Energy Conversion and Storage, School of Chemistry and Chemical Engineering, Harbin Institute of Technology Harbin Heilongjiang 150001 China
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Affiliation(s)
- Qichi Hu
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Julia Laskin
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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Johnson GE, Gunaratne D, Laskin J. Soft- and reactive landing of ions onto surfaces: Concepts and applications. Mass Spectrom Rev 2016; 35:439-479. [PMID: 25880894 DOI: 10.1002/mas.21451] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 10/31/2014] [Indexed: 06/04/2023]
Abstract
Soft- and reactive landing of mass-selected ions is gaining attention as a promising approach for the precisely-controlled preparation of materials on surfaces that are not amenable to deposition using conventional methods. A broad range of ionization sources and mass filters are available that make ion soft-landing a versatile tool for surface modification using beams of hyperthermal (<100 eV) ions. The ability to select the mass-to-charge ratio of the ion, its kinetic energy and charge state, along with precise control of the size, shape, and position of the ion beam on the deposition target distinguishes ion soft landing from other surface modification techniques. Soft- and reactive landing have been used to prepare interfaces for practical applications as well as precisely-defined model surfaces for fundamental investigations in chemistry, physics, and materials science. For instance, soft- and reactive landing have been applied to study the surface chemistry of ions isolated in the gas-phase, prepare arrays of proteins for high-throughput biological screening, produce novel carbon-based and polymer materials, enrich the secondary structure of peptides and the chirality of organic molecules, immobilize electrochemically-active proteins and organometallics on electrodes, create thin films of complex molecules, and immobilize catalytically active organometallics as well as ligated metal clusters. In addition, soft landing has enabled investigation of the size-dependent behavior of bare metal clusters in the critical subnanometer size regime where chemical and physical properties do not scale predictably with size. The morphology, aggregation, and immobilization of larger bare metal nanoparticles, which are directly relevant to the design of catalysts as well as improved memory and electronic devices, have also been studied using ion soft landing. This review article begins in section 1 with a brief introduction to the existing applications of ion soft- and reactive landing. Section 2 provides an overview of the ionization sources and mass filters that have been used to date for soft landing of mass-selected ions. A discussion of the competing processes that occur during ion deposition as well as the types of ions and surfaces that have been investigated follows in section 3. Section 4 discusses the physical phenomena that occur during and after ion soft landing, including retention and reduction of ionic charge along with factors that impact the efficiency of ion deposition. The influence of soft landing on the secondary structure and biological activity of complex ions is addressed in section 5. Lastly, an overview of the structure and mobility as well as the catalytic, optical, magnetic, and redox properties of bare ionic clusters and nanoparticles deposited onto surfaces is presented in section 6.
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Affiliation(s)
- Grant E Johnson
- Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, MSIN K8-88, Richland, WA, 99352
| | - Don Gunaratne
- Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, MSIN K8-88, Richland, WA, 99352
| | - Julia Laskin
- Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, MSIN K8-88, Richland, WA, 99352
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Gunaratne KDD, Prabhakaran V, Ibrahim YM, Norheim RV, Johnson GE, Laskin J. Design and performance of a high-flux electrospray ionization source for ion soft landing. Analyst 2015; 140:2957-63. [DOI: 10.1039/c5an00220f] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A high-flux electrospray source enables deposition of micrograms of mass-selected ions for studies in catalysis and materials science.
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Affiliation(s)
| | | | - Yehia M. Ibrahim
- Biological Sciences Division and Environmental Molecular Sciences Laboratory
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Randolph V. Norheim
- Biological Sciences Division and Environmental Molecular Sciences Laboratory
- Pacific Northwest National Laboratory
- Richland
- USA
| | - Grant E. Johnson
- Pacific Northwest National Laboratory
- Physical Sciences Division
- Richland
- USA
| | - Julia Laskin
- Pacific Northwest National Laboratory
- Physical Sciences Division
- Richland
- USA
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Abstract
Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)3](2+) (bpy = bipyridine), onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.
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Affiliation(s)
- Grant E Johnson
- Physical Sciences Division, Pacific Northwest National Laboratory
| | | | - Julia Laskin
- Physical Sciences Division, Pacific Northwest National Laboratory;
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Pratihar S, Kohale SC, Vázquez SA, Hase WL. Intermolecular potential for binding of protonated peptide ions with perfluorinated hydrocarbon surfaces. J Phys Chem B 2014; 118:5577-88. [PMID: 24779856 DOI: 10.1021/jp410886s] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
An analytic potential energy function was developed to model both short-range and long-range interactions between protonated peptide ions and perfluorinated hydrocarbon chains. The potential function is defined as a sum of two-body potentials of the Buckingham form. The parameters of the two-body potentials were obtained by fits to intermolecular potential energy curves (IPECs) calculated for CF4, which represents the F and C atoms of a perfluoroalkane chain, interacting with small molecules chosen as representatives of the main functional groups and atoms present in protonated peptide ions: specifically, CH4, NH3, NH4(+), and HCOOH. The IPECs were calculated at the MP2/aug-cc-pVTZ level of theory, with basis set superposition error (BSSE) corrections. Good fits were obtained for an energy range extending up to about 400 kcal/mol. It is shown that the pair potentials derived from the NH3/CF4 and HCOOH/CF4 fits reproduce acceptably well the intermolecular interactions in HCONH2/CF4, which indicates that the parameters obtained for the amine and carbonyl atoms may be transferable to the corresponding atoms of the amide group. The derived potential energy function may be used in chemical dynamics simulations of collisions of peptide-H(+) ions with perfluorinated hydrocarbon surfaces.
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Affiliation(s)
- Subha Pratihar
- Department of Chemistry and Biochemistry, Texas Tech University , Lubbock, Texas 79409-1061, United States
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Affiliation(s)
- Jobin Cyriac
- DST Unit of
Nanoscience, Department
of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United
States
| | - T. Pradeep
- DST Unit of
Nanoscience, Department
of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, India
| | - H. Kang
- Department of Chemistry, Seoul National University, Gwanak-gu, Seoul 151-747,
Republic of Korea
| | - R. Souda
- International
Center for Materials
Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - R. G. Cooks
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United
States
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Cyriac J, Li G, Cooks RG. Vibrational Spectroscopy and Mass Spectrometry for Characterization of Soft Landed Polyatomic Molecules. Anal Chem 2011; 83:5114-21. [PMID: 21634371 DOI: 10.1021/ac200118f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Jobin Cyriac
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Guangtao Li
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - R. Graham Cooks
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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Abstract
Soft and reactive landing of mass-selected ions onto surfaces has become a topic of substantial interest due to its promising potential for the highly controlled preparation of materials. For example, there are possible applications in the production of peptide and protein microarrays for use in high-throughput screening, protein separation and conformational enrichment of peptides, redox protein characterization, thin-film production, and the preparation of catalysts through deposition of clusters and organometallic complexes. Soft landing overcomes many of the limitations associated with conventional thin-film production techniques and offers unprecedented selectivity and specificity of preparation of deposited species. This review discusses the fundamental aspects of soft and reactive landing of mass-selected ions on surfaces that pertain to applications of these techniques in biomaterials, molecular electronics, catalysis, and interfacial chemistry.
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Affiliation(s)
- Grant E Johnson
- Fundamental Science Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
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Johnson GE, Lysonski M, Laskin J. In Situ Reactivity and TOF-SIMS Analysis of Surfaces Prepared by Soft and Reactive Landing of Mass-Selected Ions. Anal Chem 2010; 82:5718-27. [DOI: 10.1021/ac100734g] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Grant E. Johnson
- Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, MSIN K8-88, Richland, Washington 99352
| | - Michael Lysonski
- Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, MSIN K8-88, Richland, Washington 99352
| | - Julia Laskin
- Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, MSIN K8-88, Richland, Washington 99352
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Mazzei F, Favero G, Frasconi M, Tata A, Pepi F. Electron-Transfer Kinetics of Microperoxidase-11 Covalently Immobilised onto the Surface of Multi-Walled Carbon Nanotubes by Reactive Landing of Mass-Selected Ions. Chemistry 2009; 15:7359-67. [DOI: 10.1002/chem.200900887] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Affiliation(s)
- Wen-Ping Peng
- Department of Chemistry, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907
| | - Michael P. Goodwin
- Department of Chemistry, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907
| | - Zongxiu Nie
- Department of Chemistry, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907
| | - Michael Volný
- Department of Chemistry, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907
| | - Zheng Ouyang
- Department of Chemistry, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907
| | - R. Graham Cooks
- Department of Chemistry, 560 Oval Drive, Purdue University, West Lafayette, Indiana 47907
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Mazzei F, Favero G, Frasconi M, Tata A, Tuccitto N, Licciardello A, Pepi F. Soft-Landed Protein Voltammetry: A Tool for Redox Protein Characterization. Anal Chem 2008; 80:5937-44. [DOI: 10.1021/ac8005389] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Franco Mazzei
- Dipartimento di Chimica e Tecnologie del Farmaco, “Sapienza” Università di Roma, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Viale Andrea Doria 6, 95125 Catania, Italy
| | - Gabriele Favero
- Dipartimento di Chimica e Tecnologie del Farmaco, “Sapienza” Università di Roma, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Viale Andrea Doria 6, 95125 Catania, Italy
| | - Marco Frasconi
- Dipartimento di Chimica e Tecnologie del Farmaco, “Sapienza” Università di Roma, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Viale Andrea Doria 6, 95125 Catania, Italy
| | - Alessandra Tata
- Dipartimento di Chimica e Tecnologie del Farmaco, “Sapienza” Università di Roma, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Viale Andrea Doria 6, 95125 Catania, Italy
| | - Nunzio Tuccitto
- Dipartimento di Chimica e Tecnologie del Farmaco, “Sapienza” Università di Roma, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Viale Andrea Doria 6, 95125 Catania, Italy
| | - Antonino Licciardello
- Dipartimento di Chimica e Tecnologie del Farmaco, “Sapienza” Università di Roma, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Viale Andrea Doria 6, 95125 Catania, Italy
| | - Federico Pepi
- Dipartimento di Chimica e Tecnologie del Farmaco, “Sapienza” Università di Roma, Piazzale Aldo Moro 5, 00185 Roma, Italy, and Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Viale Andrea Doria 6, 95125 Catania, Italy
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Wang P, Hadjar O, Gassman PL, Laskin J. Reactive landing of peptide ions on self-assembled monolayer surfaces: an alternative approach for covalent immobilization of peptides on surfaces. Phys Chem Chem Phys 2008; 10:1512-22. [PMID: 18327307 DOI: 10.1039/b717617a] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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.
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Affiliation(s)
- Peng Wang
- Pacific Northwest National Laboratory, Fundamental Science Directorate, Richland, WA 99352, USA
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