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- Jones, E. A., et al.
(författare)
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ToF-SIMS analysis of bio-systems: Are polyatomic primary ions the solution?
- 2006
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 252:19, s. 6844-6854
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Konferensbidrag (refereegranskat)abstract
- We discuss the potential of cluster ion beams for overcoming difficulties experienced within molecular analysis in conventional static secondary ion mass spectrometry (SIMS). Consideration of secondary ion yield, surface damage and molecular depth profiling is included. Examples of the greatly increased secondary ion yields from 'real world' samples such as bacterial membranes are illustrated, the increase in information then benefiting multivariate analysis techniques such as principal component analysis (PCA). The increased efficiency of secondary ion formation with cluster beams, in conjunction with the reduced subsurface damage associated with C-60 bombardment is exemplified using a depth profile through a phospholipid layer, where molecular information is obtained even following doses of 2 x 10(15) ions/cm(2). This is developed further to the identification of molecular ions from the interior of etched cells. Challenges that cannot be solved solely by increased secondary ion yields and low sample damage have been considered and complications due to the influence of matrix effects along with the effect of salt concentration on the fate of molecular signals in depth profiles of biomaterials have been investigated. (c) 2006 Elsevier B.V. All rights reserved.
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- Yokoyama, Y., et al.
(författare)
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Peptide Fragmentation and Surface Structural Analysis by Means of ToF-SIMS Using Large Cluster Ion Sources
- 2016
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Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 88:7, s. 3592-3597
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Tidskriftsartikel (refereegranskat)abstract
- Peptide or protein structural analysis is crucial for the evaluation of biochips and biodevices, therefore an analytical technique with the ability to detect and identify protein and peptide species directly from surfaces with high lateral resolution is required. In this report, the efficacy of ToF-SIMS to analyze and identify proteins directly from surfaces is evaluated. Although the physics governing the SIMS bombardment process precludes the ability for researchers to detect intact protein or larger peptides of greater than a few thousand mass unit directly, it is possible to obtain information on the partial structures of peptides or proteins using low energy per atom argon duster ion beams. Large cluster ion beams, such as Ar dusters and C-60 ion beams, produce spectra similar to those generated by tandem MS. The SIMS bombardment process also produces peptide fragment ions not detected by conventional MS/MS techniques. In order to clarify appropriate measurement conditions for peptide structural analysis, peptide fragmentation dependency on the energy of a primary ion beam and ToF-SIMS specific fragment ions are evaluated. It was found that the energy range approximately 6 <= E/n <= 10 eV/atom is most effective for peptide analysis based on peptide fragments and [M + H] ions. We also observed the cleaving of side chain moieties at extremely low-energy E/n <= 4 eV/atom.
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- Armitage, Emily G, et al.
(författare)
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Time-of-flight SIMS as a novel approach to unlocking the hypoxic properties of cancer
- 2013
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Ingår i: Surface and Interface Analysis. - 1096-9918 .- 0142-2421. ; 45:1, s. 282-285
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Tidskriftsartikel (refereegranskat)abstract
- It is known that hypoxia-inducible factor 1 (HIF-1) activity results in the coordinated up-regulation of a large number of proteins that facilitate cell survival in tumours; however, the effect of HIF-1 on cancer metabolism is less well characterised. With knowledge of the specific effect of HIF-1 on cancer metabolism, biomarkers could be identified for which new drugs could be targeted. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) offers the potential to analyse intact cells in situ and has a mass spectral coverage that is applicable to metabolic profiling. It has been used to analyse the effects of HIF-1 on multicellular tumour models. Multicellular tumour spheroids (MTSs) have been cultured from human colon carcinoma cells with and without the expression of HIF-1, and the surface of the cross sections of each MTS has been analysed. Because metabolic profiling is an emerging field in ToF-SIMS, there is a requirement to determine which metabolites can be detected using this technique and which of those can be identified in complex mixtures within biological samples. For this, a selection of metabolites have been analysed, and the ToF-SIMS standard spectra acquired have been used to localise metabolites in MTS sections. The comparison of metabolic profiles of MTSs with and without the expression of HIF-1 has elucidated potential biomarkers for tumour survival in hypoxia, some of which may be HIF-1 regulated.
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- Fletcher, John, 1978, et al.
(författare)
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Rapid discrimination of the causal agents of urinary tract infection using ToF-SIMS with chemometric cluster analysis
- 2006
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 252:19, s. 6869-6874
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Konferensbidrag (refereegranskat)abstract
- Advances in time of flight secondary ion mass spectrometry (ToF-SIMS) have enabled this technique to become a powerful tool for the analysis of biological samples. Such samples are often very complex and as a result full interpretation of the acquired data can be extremely difficult. To simplify the interpretation of these information rich data, the use of chemometric techniques is becoming widespread in the ToF-SIMS community. Here we discuss the application of principal components-discriminant function analysis (PC-DFA) to the separation and classification of a number of bacterial samples that are known to be major causal agents of urinary tract infection. A large data set has been generated using three biological replicates of each isolate and three machine replicates were acquired from each biological replicate. Ordination plots generated using the PC-DFA are presented demonstrating strain level discrimination of the bacteria. The results are discussed in terms of biological differences between certain species and with reference to FT-IR, Raman spectroscopy and pyrolysis mass spectrometric studies of similar samples. (c) 2006 Elsevier B.V. All rights reserved.
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- Fletcher, John S., et al.
(författare)
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Prospect of increasing secondary ion yields in ToF-SIMS using water cluster primary ion beams
- 2014
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Ingår i: Surface and Interface Analysis. - : Wiley. - 0142-2421 .- 1096-9918. ; 46, s. 51-53
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Tidskriftsartikel (refereegranskat)abstract
- Low ionization yields in time of flight secondary ion mass spectrometry (ToF-SIMS) particularly from single cells and tissues are proving to be a significant limitation in allowing this technique to reach its full potential. A number of approaches including embedding the sample in water or spraying water above sample surface has shown great prospective for increasing the ionization yield by a factor of 10 to 100 through proton mediated' reaction. Based on this hypothesis, a water cluster primary ion source has been developed in collaboration with Ionoptika Ltd to generate giant water cluster ions (H2O)(n)(+) (n=1-10000) using a similar supersonic jet expansion methodology as for argon cluster beams. The ion yields of arginine, cholesterol, angiotensin II and a lipid mix have been measured under static and high ion dose conditions using (H2O)(5000)(+), (H2O)(3000)(+), Ar-3000(+) and C-60(+) primary ion beams at 20keV. An enhancement in yields up to a factor of around 4 is observed under water cluster impact, in comparison with C-60(+) at 1x10(11)ions/cm(2) ion dose, whereas this increases by around 10-50 times at high ion dose conditions. Copyright (c) 2014 John Wiley & Sons, Ltd.
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- Kawashima, T., et al.
(författare)
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Examination of fragment ions of polystyrene in TOF-SIMS spectra using MS/MS
- 2014
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Ingår i: Surface and Interface Analysis. - : Wiley. - 0142-2421 .- 1096-9918. ; 46, s. 92-95
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Tidskriftsartikel (refereegranskat)abstract
- In this study, tendencies of ionization and cleavage processes of time-of-flight (TOF)-SIMS were examined using MS/MS, which enables an easy qualitative analysis of organic matters, to clarify the fragment ions showing structures of the organic materials. In this paper, a result of reviewing fragment ions in TOF-SIMS spectra for polystyrene (PS) as the representative material is shown. Samples were measured with collision induced dissociation (CID)-MS/MS of 1200L (Varian Inc., USA) and TOF-SIMS J105 (Ionoptika Ltd, UK) for the examination of fragment ions of the PS in TOF-SIMS spectra. The use of CID MS/MS with a wide range of energy distribution is effective for the study of the ionization and cleavage process of TOF-SIMS. As a result, the fragment ions representing the PS structure were clarified, which is useful for the material definition. The qualitative analysis was also applied to the fragment ions particularly obtained in this examination. It is suggested that the examination of the fragmentation process using MS/MS is useful for the mass spectra analysis of organic materials in TOF-SIMS. Copyright (c) 2014 John Wiley & Sons, Ltd.
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| 11. |
- Kotze, Helen L., et al.
(författare)
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ToF-SIMS as a tool for metabolic profiling small biomolecules in cancer systems
- 2013
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Ingår i: Surface and Interface Analysis. - 1096-9918 .- 0142-2421. ; 45:1, s. 277-281
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Tidskriftsartikel (refereegranskat)abstract
- Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is emerging as a tool for studying the metabolism of disease. ToF-SIMS enables chemical specificity in addition to high spatial resolution imaging of biological samples from cells to tissue. Here, ToF-SIMS has been used to investigate the metabolic regulation of hypoxia-induced chemoresistance to doxorubicin treatment using multicellular tumour spheroids. Imaging principal component analysis (PCA) was used as a tool to identify the regions of chemistry present within the image that differ as a result of drug treatment. A series of metabolite ToF-SIMS spectra were acquired, which were used to identify quasi-molecular ions and fragments correlated to the PCA loading plots. Metabolite patterns have been identified as potential biomarkers of hypoxia-induced chemoresistance.
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