On the Separation of Isotopes in Quantity by Electromagnetic Means

Smith, Lloyd P.; Parkins, William E.; Forrester, A. Theodore

doi:10.1103/physrev.72.989

Cited by 51 publications

(19 citation statements)

References 5 publications

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“…The giant effort to enrich fissionable materials for the first nuclear explosions in the 1940s was the singular example of using pMS in the distant past of mass spectrometry's 100-year history (29). At that time this approach was too inefficient for other applications.…”

Section: Introductionmentioning

confidence: 99%

Mass Spectrometry as a Preparative Tool for the Surface Science of Large Molecules

Rauschenbach

Ternes

Harnau

et al. 2016

Annual Rev. Anal. Chem.

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Measuring and understanding the complexity that arises when nanostructures interact with their environment are one of the major current challenges of nanoscale science and technology. High-resolution microscopy methods such as scanning probe microscopy have the capacity to investigate nanoscale systems with ultimate precision, for which, however, atomic scale precise preparation methods of surface science are a necessity. Preparative mass spectrometry (pMS), defined as the controlled deposition of m/z filtered ion beams, with soft ionization sources links the world of large, biological molecules and surface science, enabling atomic scale chemical control of molecular deposition in ultrahigh vacuum (UHV). Here we explore the application of high-resolution scanning probe microscopy and spectroscopy to the characterization of structure and properties of large molecules. We introduce the fundamental principles of the combined experiments electrospray ion beam deposition and scanning tunneling microscopy. Examples for the deposition and investigation of single particles, for layer and film growth, and for the investigation of electronic properties of individual nonvolatile molecules show that state-of-the-art pMS technology provides a platform analog to thermal evaporation in conventional molecular beam epitaxy. Additionally, it offers additional, unique features due to the use of charged polyatomic particles. This new field is an enormous sandbox for novel molecular materials research and demands the development of advanced molecular ion beam technology.

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Section: Introductionmentioning

confidence: 99%

Mass Spectrometry as a Preparative Tool for the Surface Science of Large Molecules

Rauschenbach

Ternes

Harnau

et al. 2016

Annual Rev. Anal. Chem.

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“…Preparation of directionally aligned ahelical peptide layers on substrates has attracted significant attention because the resulting strong net dipole is useful for a variety of applications in photonics, [2,3] molecular electronics, [4] and catalysis. Existing technologies for the production of a-helical peptide surfaces are based on a variety of solution-phase synthetic strategies [2,5,8] that usually require relatively large quantities of purified materials.Preparative mass spectrometry based on soft landing (SL) [9][10][11][12][13][14][15][16][17][18] of mass-selected ions is a viable alternative to the existing surface modification approaches. Existing technologies for the production of a-helical peptide surfaces are based on a variety of solution-phase synthetic strategies [2,5,8] that usually require relatively large quantities of purified materials.…”

mentioning

confidence: 99%

Helical Peptide Arrays on Self‐Assembled Monolayer Surfaces through Soft and Reactive Landing of Mass‐Selected Ions

Wang

Laskin

2008

Angew Chem Int Ed

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The a helix, a common building block of the protein secondary structure, plays an important role in determining protein structure and function. The biological function of the a helix is mainly attributed to its large macrodipole [1] originating from the alignment of individual dipole moments of peptide bonds. Preparation of directionally aligned ahelical peptide layers on substrates has attracted significant attention because the resulting strong net dipole is useful for a variety of applications in photonics, [2,3] molecular electronics, [4] and catalysis. [5][6][7] In addition, conformationally-selected a-helical peptide arrays can be used for detailed characterization of molecular recognition steps critical for protein folding, enzyme function, and DNA binding by proteins. Existing technologies for the production of a-helical peptide surfaces are based on a variety of solution-phase synthetic strategies [2,5,8] that usually require relatively large quantities of purified materials.Preparative mass spectrometry based on soft landing (SL) [9][10][11][12][13][14][15][16][17][18] of mass-selected ions is a viable alternative to the existing surface modification approaches. It has been demonstrated that SL enables highly specific preparation of uniform thin films of biological molecules on substrates. [19][20][21] In addition, reactive landing (RL), in which SL is followed by covalent linking of molecules to chemically reactive surfaces, can be used for controlled immobilization of peptides and proteins on solid supports. [22,23] Because SL is a relatively gentle ion deposition technique, it is easy to preserve the primary structure of deposited species. However, it is very difficult to control the secondary structure of soft-landed biomolecules, because electrospray ionization (ESI) utilized in these experiments generates ions in a variety of different conformations. Previous studies reported retention of the secondary and possibly tertiary structure by soft-landed proteins. [19a, 21, 22] Herein, we demonstrate that SL can be used to prepare peptides on substrates in stable conformations that do not exist in solution.This study focuses on the preparation of conformationally-selected peptide arrays using SL of mass selected peptide ions on self-assembled monolayer (SAM) surfaces. The singly protonated Ac-A 15 K peptide was selected as a model system for this study because ion mobility measurements and molecular dynamics (MD) simulations demonstrated that this peptide forms a very stable a-helical conformation in the gas phase, which is stabilized by the interaction between the protonated C-terminal lysine residue and the dipole of the helix.[24] Formation of the a-helical peptide array is demonstrated on an inert SAM of alkylthiol on gold (HSAM) and covalent immobilization of the Ac-A 15 K peptide on a reactive SAM of N-hydroxysuccinimidyl ester terminated alkylthiol on gold (NHS-SAM) with retention of the secondary structure. Because the NHS-SAM surface readily reacts with primary amino groups in proteins or pepti...

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“…To accomplish this, we collected the viral ions from a glycerol-coated brass plate placed in front of the detector (Figure 3a). The separation and collection of ions within a mass spectrometer for purification was inspired by early Calutron mass spectrometers used to separate uranium isotopes [16]. The isolated virus sample was then directly analyzed by negative-stain transmission electron microscopy (TEM).…”

Section: Virus and Spore Viabilitymentioning

confidence: 99%

“…Another motivation for analyzing viruses was that while convincing evidence existed regarding the observation of noncovalent interactions with mass spectrometry [1–7, 10], a common question was (and still is) whether native conformations are preserved throughout the vaporization, ionization and mass analysis within the vacuum of the mass spectrometer [15]. A third question, reminiscent of the Manhattan Project where Calutron mass spectrometers were used to separate uranium isotopes [16], is whether this technology can be used as a viable separation and collection device for biomolecules. Our work on viruses attempted to address these issues with the analysis 40 MDa tobacco mosaic virus.…”

Section: Introductionmentioning

confidence: 99%

Staying Alive: Measuring Intact Viable Microbes with Electrospray Ionization Mass Spectrometry

Forsberg

Fang

Siuzdak

2016

J. Am. Soc. Mass Spectrom.

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Mass spectrometry has traditionally been the technology of choice for small molecule analysis, making significant inroads into metabolism, clinical diagnostics and pharmacodynamics since the 1960s. In the mid 1980s, with the discovery of electrospray ionization (ESI) for biomolecule analysis, a new door opened for applications beyond small molecules. Initially proteins were widely examined, followed by oligonucleotides and other nonvolatile molecules. Then in 1991, three intriguing studies reported using mass spectrometry to examine noncovalent protein complexes, results that have been expanded on for the last 25 years. Those experiments also raised the question, how soft is ESI and can it be used to examine even more complex interactions. Our lab addressed these questions with the analyses of viruses, which were initially tested for viability following electrospray ionization and their passage through a quadrupole mass analyzer by placing them on an active medium that would allow them to propagate. This observation has been replicated on multiple different systems including experiments on an even bigger microbe, a spore. The question of analysis was also addressed in the early 2000’s with charge detection mass spectrometry. This unique technology could simultaneously measure mass-to-charge and charge, allowing for the direct determination of the mass of a virus. More recent experiments on spores and enveloped viruses have given us insight into the range of mass spectrometry’s capabilities (reaching 100 trillion daltons), beginning to answer fundamental questions regarding the complexity of these organisms beyond proteins and genes, and how small molecules are integral to these supramolecular living structures.

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On the Separation of Isotopes in Quantity by Electromagnetic Means

Cited by 51 publications

References 5 publications

Mass Spectrometry as a Preparative Tool for the Surface Science of Large Molecules

Mass Spectrometry as a Preparative Tool for the Surface Science of Large Molecules

Helical Peptide Arrays on Self‐Assembled Monolayer Surfaces through Soft and Reactive Landing of Mass‐Selected Ions

Staying Alive: Measuring Intact Viable Microbes with Electrospray Ionization Mass Spectrometry

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