Soft laser desorption

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Soft laser desorption (SLD) is laser desorption of large molecules that results in ionization without fragmentation. "Soft" in the context of ion formation means forming ions without breaking chemical bonds. "Hard" ionization is the formation of ions with the breaking of bonds and the formation of fragment ions.

Contents

Background

The term "soft laser desorption" has not been widely used by the mass spectrometry community, which in most cases uses matrix-assisted laser desorption/ionization (MALDI) to indicate soft laser desorption ionization that is aided by a separate matrix compound. The term soft laser desorption was used most notably by the Nobel Foundation in public information released in conjunction with the 2002 Nobel Prize in Chemistry. [1] Koichi Tanaka was awarded 1/4 of the prize for his use of a mixture of cobalt nanoparticles and glycerol in what he called the “ultra fine metal plus liquid matrix method” of laser desorption ionization. With this approach, he was able to demonstrate the soft ionization of proteins. [2] The MALDI technique was demonstrated (and the name coined) in 1985 by Michael Karas, Doris Bachmann, and Franz Hillenkamp, [3] but ionization of proteins by MALDI was not reported until 1988, immediately after Tanaka's results were reported.

Some have argued that Karas and Hillenkamp were more deserving of the Nobel Prize than Tanaka because their crystalline matrix method is much more widely used than Tanaka's liquid matrix. [4] [5] Countering this argument is the fact that Tanaka was the first to use a 337 nm nitrogen laser while Karas and Hillenkamp were using a 266 nm Nd:YAG laser. The "modern" MALDI approach came into being several years after the first soft laser desorption of proteins was demonstrated. [6] [7] [8]

The term soft laser desorption is now used to refer to MALDI as well as "matrix free" methods for laser desorption ionization with minimal fragmentation. [9]

Variants

Graphite

The surface-assisted laser desorption/ionization (SALDI) approach uses a liquid plus graphite particle matrix. [10] [11] A colloidal graphite matrix has been called "GALDI" for colloidal graphite-assisted laser desorption/ionization. [12]

Nanostructured surfaces

The desorption ionization on silicon (DIOS) approach is laser desorption/ionization of a sample deposited on a porous silicon surface. [13] Nanostructure-initiator mass spectrometry (NIMS) is a variant of DIOS that uses "initiator" molecules trapped in the nanostructures. [14] Although nanostructures are typically formed by etching, laser etching can also be used, for example as in laser-induced silicon microcolumn arrays (LISMA) for matrix-free mass spectrometry analysis. [15]

Nanowires

A commercial NALDI target NALDI Target.jpg
A commercial NALDI target

Silicon nanowires were initially developed as a DIOS-MS application. [16] This approach was later commercialized as Nanowire-assisted laser desorption/ionization (NALDI) uses a target consisting of nanowires made from metal oxides or nitrides. [17] NALDI targets are available from Bruker Daltonics (although they are marketed as "nanostructured" rather than "nanowire" targets).

Surface-enhanced laser desorption/ionization (SELDI)

The surface-enhanced laser desorption/ionization (SELDI) variant is similar to MALDI, but uses a biochemical affinity target. [18] [19] The technique known as surface-enhanced neat desorption (SEND) [18] is a related variant of MALDI with the matrix is covalently linked to the target surface. The SELDI technology was commercialized by Ciphergen Biosystems in 1997 as the ProteinChip system. It is now produced and marketed by Bio-Rad Laboratories.

Other methods

The technique known as laser induced acoustic desorption (LIAD) is transmission geometry LDI with a metal film target. [20] [21]

Related Research Articles

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<span class="mw-page-title-main">Ion source</span> Device that creates charged atoms and molecules (ions)

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<span class="mw-page-title-main">Koichi Tanaka</span> Japanese electrical engineer (born 1959)

Koichi Tanaka is a Japanese electrical engineer who shared the Nobel Prize in Chemistry in 2002 for developing a novel method for mass spectrometric analyses of biological macromolecules with John Bennett Fenn and Kurt Wüthrich.

<span class="mw-page-title-main">Matrix-assisted laser desorption/ionization</span> Ionization technique

In mass spectrometry, matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that uses a laser energy-absorbing matrix to create ions from large molecules with minimal fragmentation. It has been applied to the analysis of biomolecules and various organic molecules, which tend to be fragile and fragment when ionized by more conventional ionization methods. It is similar in character to electrospray ionization (ESI) in that both techniques are relatively soft ways of obtaining ions of large molecules in the gas phase, though MALDI typically produces far fewer multi-charged ions.

<span class="mw-page-title-main">History of mass spectrometry</span>

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<span class="mw-page-title-main">MALDI imaging</span>

MALDI mass spectrometry imaging (MALDI-MSI) is the use of matrix-assisted laser desorption ionization as a mass spectrometry imaging technique in which the sample, often a thin tissue section, is moved in two dimensions while the mass spectrum is recorded. Advantages, like measuring the distribution of a large amount of analytes at one time without destroying the sample, make it a useful method in tissue-based study.

<span class="mw-page-title-main">Protein mass spectrometry</span> Application of mass spectrometry

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<span class="mw-page-title-main">Matrix-assisted laser desorption electrospray ionization</span>

Matrix-assisted laser desorption electrospray ionization (MALDESI) was first introduced in 2006 as a novel ambient ionization technique which combines the benefits of electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI). An infrared (IR) or ultraviolet (UV) laser can be utilized in MALDESI to resonantly excite an endogenous or exogenous matrix. The term 'matrix' refers to any molecule that is present in large excess and absorbs the energy of the laser, thus facilitating desorption of analyte molecules. The original MALDESI design was implemented using common organic matrices, similar to those used in MALDI, along with a UV laser. The current MALDESI source employs endogenous water or a thin layer of exogenously deposited ice as the energy-absorbing matrix where O-H symmetric and asymmetric stretching bonds are resonantly excited by a mid-IR laser.

<span class="mw-page-title-main">Desorption atmospheric pressure photoionization</span>

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<span class="mw-page-title-main">Ambient ionization</span>

Ambient ionization is a form of ionization in which ions are formed in an ion source outside the mass spectrometer without sample preparation or separation. Ions can be formed by extraction into charged electrospray droplets, thermally desorbed and ionized by chemical ionization, or laser desorbed or ablated and post-ionized before they enter the mass spectrometer.

<span class="mw-page-title-main">Franz Hillenkamp</span> German chemist (1936–2014)

Franz Hillenkamp was a German scientist known for his development of the laser microprobe mass analyzer and, with Michael Karas, matrix-assisted laser desorption/ionization (MALDI).

<span class="mw-page-title-main">Surface-assisted laser desorption/ionization</span>

Surface-assisted laser desorption/ionization (SALDI) is a soft laser desorption technique used for mass spectrometry analysis of biomolecules, polymers, and small organic molecules. In its first embodiment Koichi Tanaka used a cobalt/glycerol liquid matrix and subsequent applications included a graphite/glycerol liquid matrix as well as a solid surface of porous silicon. The porous silicon represents the first matrix-free SALDI surface analysis allowing for facile detection of intact molecular ions, these porous silicon surfaces also facilitated the analysis of small molecules at the yoctomole level. At present laser desorption/ionization methods using other inorganic matrices such as nanomaterials are often regarded as SALDI variants. As an example, silicon nanowires as well as Titania nanotube arrays (NTA) have been used as substrates to detect small molecules. SALDI is used to detect proteins and protein-protein complexes. A related method named "ambient SALDI" - which is a combination of conventional SALDI with ambient mass spectrometry incorporating the direct analysis real time (DART) ion source has also been demonstrated. SALDI is considered one of the most important techniques in MS and has many applications.

<span class="mw-page-title-main">Robert J. Cotter</span>

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<span class="mw-page-title-main">Desorption/ionization on silicon</span> Soft laser desorption method

Desorption/ionization on silicon (DIOS) is a soft laser desorption method used to generate gas-phase ions for mass spectrometry analysis. DIOS is considered the first surface-based surface-assisted laser desorption/ionization (SALDI-MS) approach. Prior approaches were accomplished using nanoparticles in a matrix of glycerol, while DIOS is a matrix-free technique in which a sample is deposited on a nanostructured surface and the sample desorbed directly from the nanostructured surface through the adsorption of laser light energy. DIOS has been used to analyze organic molecules, metabolites, biomolecules and peptides, and, ultimately, to image tissues and cells.

In mass spectrometry, a matrix is a compound that promotes the formation of ions. Matrix compounds are used in matrix-assisted laser desorption/ionization (MALDI), matrix-assisted ionization (MAI), and fast atom bombardment (FAB).

References

  1. ↑ "The Nobel Prize in Chemistry 2002". The Nobel Foundation. 9 October 2002. Retrieved 2013-01-31.
  2. ↑ Tanaka, Koichi; Hiroaki Waki; Yutaka Ido; Satoshi Akita; Yoshikazu Yoshida; Tamio Yoshida; T. Matsuo (1988). "Protein and polymer analyses up to m/z 100 000 by laser ionization time-of-flight mass spectrometry". Rapid Communications in Mass Spectrometry . 2 (8): 151–153. Bibcode:1988RCMS....2..151T. doi:10.1002/rcm.1290020802.
  3. ↑ Karas, M.; Bachmann, D.; Hillenkamp, F. (1985). "Influence of the Wavelength in High-Irradiance Ultraviolet Laser Desorption Mass Spectrometry of Organic Molecules". Anal. Chem. 57 (14): 2935–9. doi:10.1021/ac00291a042.
  4. ↑ Spinney, Laura (December 11, 2002). "Nobel Prize controversy". The Scientist. Archived from the original on May 17, 2007. Retrieved 2007-08-29.
  5. ↑ "ABC News Online: 2002 Nobel chemistry choice sparks protest". B.U. Bridge. Boston University. December 2002. Retrieved 2007-08-29.
  6. ↑ Beavis RC, Chait BT (1989). "Matrix-assisted laser-desorption mass spectrometry using 355 nm radiation". Rapid Commun. Mass Spectrom. 3 (12): 436–9. Bibcode:1989RCMS....3..436B. doi:10.1002/rcm.1290031208. PMID   2520224.
  7. ↑ Beavis RC, Chait BT (1989). "Cinnamic acid derivatives as matrices for ultraviolet laser desorption mass spectrometry of proteins". Rapid Commun. Mass Spectrom. 3 (12): 432–5. Bibcode:1989RCMS....3..432B. doi:10.1002/rcm.1290031207. PMID   2520223.
  8. ↑ Strupat K, Karas M, Hillenkamp F; Karas; Hillenkamp (1991). "2,5-Dihidroxybenzoic acid: a new matrix for laser desorption-ionization mass spectrometry". Int. J. Mass Spectrom. Ion Process. 72 (111): 89–102. Bibcode:1991IJMSI.111...89S. doi:10.1016/0168-1176(91)85050-V.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ↑ Vertes, Akos (2007). "Soft Laser Desorption Ionization — Maldi, Dios and Nanostructures". Laser Ablation and its Applications. Springer Series in Optical Sciences. Vol. 129. pp. 505–528. doi:10.1007/978-0-387-30453-3_20. ISBN   978-0-387-30452-6.
  10. ↑ Sunner, J.; Dratz, E.; Chen, Y.-C. (1995). "Graphite surface-assisted laser desorption/ionization time-of-flight mass spectrometry of peptides and proteins from liquid solutions". Anal. Chem. 67 (23): 4335–42. doi:10.1021/ac00119a021. PMID   8633776.
  11. ↑ Dale, Michael J.; Knochenmuss, Richard; Zenobi, Renato (1996). "Graphite/Liquid Mixed Matrices for Laser Desorption/Ionization Mass Spectrometry". Analytical Chemistry. 68 (19): 3321–9. doi:10.1021/ac960558i. PMID   21619267.
  12. ↑ Cha, Sangwon; Yeung, Edward S. (2007). "Colloidal Graphite-Assisted Laser Desorption/Ionization Mass Spectrometry and MSnof Small Molecules. 1. Imaging of Cerebrosides Directly from Rat Brain Tissue". Analytical Chemistry. 79 (6): 2373–85. doi:10.1021/ac062251h. PMID   17288467.
  13. ↑ Wei, J.; Buriak, J. M.; Siuzdak, G. (1999). "Desorption-ionization mass spectrometry on porous silicon". Nature. 399 (6733): 243–246. Bibcode:1999Natur.399..243W. doi:10.1038/20400. PMID   10353246. S2CID   4314372.
  14. ↑ Northen, Trent R.; Yanes, Oscar; Northen, Michael T.; Marrinucci, Dena; Uritboonthai, Winnie; Apon, Junefredo; Golledge, Stephen L.; Nordström, Anders; Siuzdak, Gary (2007). "Clathrate nanostructures for mass spectrometry". Nature. 449 (7165): 1033–6. Bibcode:2007Natur.449.1033N. doi:10.1038/nature06195. PMID   17960240. S2CID   4404703.
  15. ↑ Chen, Yong; Vertes, Akos (2006). "Adjustable Fragmentation in Laser Desorption/Ionization from Laser-Induced Silicon Microcolumn Arrays". Analytical Chemistry. 78 (16): 5835–44. doi:10.1021/ac060405n. PMID   16906730.
  16. ↑ Go EP, Apon JV, Luo G, Saghatelian A, Daniels RH, Sahi V, Dubrow R, Cravatt BF, Vertes A, Siuzdak G (March 2005). "Desorption/ionization on silicon nanowires". Anal Chem. 77 (6): 1641–6. doi:10.1021/ac048460o. PMID   15762567.
  17. ↑ Kang, Min-Jung; Pyun, Jae-Chul; Lee, Jung-Chul; Choi, Young-Jin; Park, Jae-Hwan; Park, Jae-Gwan; Lee, June-Gunn; Choi, Heon-Jin (2005). "Nanowire-assisted laser desorption and ionization mass spectrometry for quantitative analysis of small molecules". Rapid Communications in Mass Spectrometry. 19 (21): 3166–3170. Bibcode:2005RCMS...19.3166K. doi:10.1002/rcm.2187.
  18. 1 2 Hutchens, T. W.; Yip, T. T. (1993). "New desorption strategies for the mass spectrometric analysis of macromolecules". Rapid Commun. Mass Spectrom. 7 (7): 576–580. Bibcode:1993RCMS....7..576H. doi:10.1002/rcm.1290070703.
  19. ↑ Poon TC (2007). "Opportunities and limitations of SELDI-TOF-MS in biomedical research: practical advices". Expert Review of Proteomics. 4 (1): 51–65. doi:10.1586/14789450.4.1.51. PMID   17288515. S2CID   30115034.
  20. ↑ Golovlev, V. V.; Allman, S. L.; Garrett, W. R.; Taranenko, N. I.; Chen, C. H. (December 1997). "Laser-induced acoustic desorption". International Journal of Mass Spectrometry and Ion Processes. 169–170: 69–78. Bibcode:1997IJMSI.169...69G. doi:10.1016/S0168-1176(97)00209-7.
  21. ↑ Somuramasami J, Kenttämaa HI (2007). "Evaluation of a Novel Approach for Peptide Sequencing: Laser-induced Acoustic Desorption Combined with Chemical Ionization and Collision-activated Dissociation in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer". J. Am. Soc. Mass Spectrom. 18 (3): 525–40. doi:10.1016/j.jasms.2006.10.009. PMC   1945181 . PMID   17157527.
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