Cluster Primary Ion Source Research Articles

Mass Spectrometry Imaging Shows Cocaine and Methylphenidate Have Opposite Effects on Major Lipids in Drosophila Brain.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to study the effects of cocaine versus methylphenidate administration on both the localization and abundance of lipids in Drosophila melanogaster brain. A J105 ToF-SIMS with a 40 keV gas cluster primary ion source enabled us to probe molecular ions of biomolecules on the fly with a spatial resolution of ∼3 μm, giving us unique insights into the effect of these drugs on molecular lipids in the nervous system. Significant changes in phospholipid composition were observed in the central brain for both. Principal components image analysis revealed that changes occurred mainly for phosphatidylcholines, phosphatidylethanolamines, and phosphatidylinositols. When the lipid changes caused by cocaine were compared with those induced by methylphenidate, it was shown that these drugs exert opposite effects on the brain lipid structure. We speculate that this might relate to the molecular mechanism of cognition and memory.

Applications of ToF-SIMS for imaging and depth profiling commercial materials

The development of cluster primary ion sources such as Aun+, Bin+, SF5+, C60+, and Arn+ has been an exciting advancement in SIMS analysis. Relative to atomic primary ion sources, cluster ion sources provide higher secondary ion yields. Furthermore, C60+ and Arn+ impart significantly less chemical damage to the sample thus enabling molecular depth profiling. Molecular depth profiling using cluster primary ion sources is routinely used to characterize a wide range of commercially important materials, including organic light emitting diode, biomaterials and pharmaceuticals, adhesives, and architectural paints and coatings. This paper highlights the application of time of flight secondary ion mass spectrometry (ToF-SIMS) to study contact lenses and acrylic-based paints. In the first application, ToF-SIMS was used to investigate the surface composition of two commercial contact lenses. Lens material I is composed of 2-hydroxy-ethyl methacrylate (HEMA) and glycerol methacrylate while lens material II is composed of HEMA and 2-methacryloxyethyl phosphorylcholine cross-linked with ethyleneglycol dimethacrylate. The ToF-SIMS data confirm the presence of the 2-methacryloxyethyl phosphorylcholine on the surface of lens material II. ToF-SIMS was also used to characterize a HEMA-based contact lens which had been worn for about 4 weeks. The analysis reveals the presence of N-containing species, fatty acids, phosphorylcholine, and dioctyldecyl dimethyl ammonium. Arn+ gas cluster ion beams (GCIB) depth profiling indicates the N-containing species, the fatty acids, and the dioctyldecyl dimethyl ammonium are concentrated at the surface. In the second application, a combination of O2+ and Arn+ GCIB depth profiling was used to study the pigment levels in acrylic-based paints. The O2+ beam was used to profile into the bulk of the dried paint film and Arn+ gas cluster beam was then used to remove the damaged material. ToF-SIMS analysis of the crater bottom reveals differences in pigment levels. The combined O2+ and Arn+ GCIB depth profiling is an effective way of characterizing materials composed of both organic and inorganic components.

Mass spectrometry imaging tools in oncology.

MS imaging allows profiling and imaging of compounds directly from tumor tissue, tissue microarrays and tissue-engineered models of tumors. Methodologies for the quantitative analysis of localized/colocalized ion signals from a single cancer cell would be a major advance. Alternative methods of generating ions to matrix-assisted laser desorption ionization are increasingly employed. Desorption electrospray ionization has been used for the intraoperative diagnosis of human brain tumors and secondary ion MS imaging with cluster primary ion sources has been used for high spatial resolution imaging tumor sections. Extensive validation of the technique for the analysis of disease biomarkers is required, if imaging MS is to have a future role in the clinic.

Prospect of increasing secondary ion yields in ToF‐SIMS using water cluster primary ion beams

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 = 1−10 000) 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+, Ar3000+ and C60+ primary ion beams at 20 keV. An enhancement in yields up to a factor of around 4 is observed under water cluster impact, in comparison with C60+ at 1 × 1011 ions/cm2 ion dose, whereas this increases by around 10–50 times at high ion dose conditions. Copyright © 2014 John Wiley & Sons, Ltd.

Are cluster ion analysis beams good choices for hydrogen depth profiling using time‐of‐flight secondary ion mass spectrometry?

AbstractFor more than three decades, time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) has been used for elemental depth profiling. In recent years, cluster primary ion sources (principally, C60+, Bin+, and Aun+) have become widely available, and they can greatly enhance the signal intensity of molecular ions (10–1000 times). Understanding the performance of cluster ion analysis beams used in elemental depth profiling can greatly assist normal ToF‐SIMS users in choosing the optimal analysis beam for depth profiling work. Presently, however, the experimental data are lacking, and such choices are difficult to make. In this paper, hydrogen and deuterium depth profiling were studied using six different analysis beams—25 keV Bi+, Bi3+, Bi5+, 50 keV Bi32+, 10 keV C60+, and 20 keV C602+. The effort shows that cluster primary ions do enhance H− and D− yields, but the enhancement is only about 1.5–4.0 times when compared to atomic Bi+ ions. Because the currents of atomic ion analysis beams are much stronger than the currents of cluster ion analysis beams for most commercial ToF‐SIMS instruments, the atomic ion analysis beams can provide the strongest H− and D− signal intensities, and may be the best choices for hydrogen and deuterium depth profiling. In addition, two representative nuclides, 30Si and 18O, were also studied and yielded results similar to those of H− and D−. Copyright © 2011 John Wiley & Sons, Ltd.

Relative Quantification of Exogenous Phospholipids Regulating Exocytosis by TOF SIMS of Hydrated Single Cells

Phospholipids in single cells have been studied by time of flight secondary ion mass spectrometry (TOF SIMS) in combination with a newly developed spring-loaded freeze fracture device. The freeze fracture device sandwiches the cell suspension between two silicon shards and is fast frozen in liquid propane at liquid nitrogen temperature. This procedure provides a snapshot of the chemical distribution in a living hydrated cell. A TOF SIMS IV instrument from ION-TOF GmbH equipped with a Bi liquid metal cluster primary ion source to image cells under static conditions was used.Single frozen hydrated rat pheochromocytoma (PC12) cellshave been used. These cells have diameters between 10 and 20 µm and are commonly used to study exocytosis. In amperometric studies we have found that incubation with lipids can alter the rate of exocytosis, apparently by altering the membrane composition. By use of a Bi cluster primary ion source, sub cellular images of phospholipids in single PC12 cells have been obtained without the need of exogenous labeling. Fragment ions from phosphatidylcholine (PC) are found at m/z 184 and 224 and fragment ions from phosphoethanolamine at m/z 124 and 142.Using the freeze fracture device we relatively quantify exogenous deuterized phospholipids that are incorporated into the plasma membrane by PC12 cells during incubation. Incubation under the same conditions as for the amperometry experiments results in membrane composition changes that are a fraction of a percent, apparently indicating that a very small change in composition leads to a significant change in the rate of exocytosis.

Relationships Between Cluster Secondary Ion Mass Intensities Generated by Different Cluster Primary Ions

Measurements are described to evaluate the constitution of secondary ion mass spectra for both monatomic and cluster primary ions. Previous work shows that spectra for different primary ions may be accurately described as the product of three material-dependent component spectra, two being raised to increasing powers as the cluster size increases. That work was for an organic material and, here, this is extended to (SiO(2))(t)OH(-) clusters from silicon oxide sputtered by 25 keV Bi(n)(+) cluster primary ions for n = 1, 3, and 5 and 1 < or = t < or = 15. These results are described to a standard deviation of 2.4% over 6 decades of intensity by the product of a constant with a spectrum, H(SiOH)*, and a power law spectrum in t. This evaluation is extended, using published data for Si(t)(+) sputtered from Si by 9 and 18 keV Au(-) and Au(3)(-), with confirmation that the spectra are closely described by the product of a constant with a spectrum, H(Si)*, and a simple spectrum that is an exponential dependence on t, both being raised to appropriate powers. This is confirmed with further published data for 6, 9, 12, and 18 keV Al(-) and Al(2)(-) primary cluster ions. In all cases, the major effect of intensity is then related to the deposited energy of the primary ion at the surface. The constitution of SIMS spectra, for monatomic and cluster primary ion sources, is shown, in all cases, to be consistent with the product of a constant with two component spectra raised to given powers.

1P-070 飛行時間型二次イオン質量分析法による固定化ポリペプチドの評価におけるクラスター一次イオン源の影響(蛋白質-計測・解析の方法論,第47回日本生物物理学会年会)

1P-070 飛行時間型二次イオン質量分析法による固定化ポリペプチドの評価におけるクラスター一次イオン源の影響(蛋白質-計測・解析の方法論,第47回日本生物物理学会年会)

Comparison of secondary ion intensity enhancement from polymers on silicon and silver substrates by using Au-TOF-SIMS

The usefulness of the usage of cluster primary ion source together with an Ag substrate and detection of Ag cationized molecular ions was studied from the standpoint to realize high sensitivity TOF-SIMS analysis of organic materials. Although secondary ions from polymer thin films on a Si substrate can be detected in a higher sensitivity with Au 3 + cluster primary ion compared with Ga + ion bombardment, it was clearly observed that the secondary ion intensities from samples on an Ag substrate showed quite a different tendency from that on Si. When monoatomic primary ions, e.g., Au + and Ga +, were used for the measurement of the sample on an Ag substrate, [M+Ag] + ions (M corresponds to polyethylene glycol molecule) were detected in a high sensitivity. On the contrary, when Au 3 + was used, no intensity enhancement of [M+Ag] + ions was observed. The acceleration energy dependence of the detected secondary ions implies the different ionization mechanisms on the different substrates.

Biomarkers at the microscopic range: ToF‐SIMS molecular imaging of Archaea‐derived lipids in a microbial mat

ABSTRACTTime‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS) with a bismuth cluster primary ion source was used for analysing microbial lipid biomarkers in 10‐µm‐thick microscopic cryosections of methanotrophic microbial mats from the Black Sea. Without further sample preparation, archaeal isopranyl glycerol di‐ and tetraether core lipids, together with their intact diglycoside (gentiobiosyl‐) derivatives, were simultaneously identified by exact mass determination. Utilizing the imaging capability of ToF‐SIMS, the spatial distributions of these biomarkers were mapped at a lateral resolution of &lt; 5 µm in 500 × 500 µm2 areas on the mat sections. Using cluster projectiles in the burst alignment mode, it was possible to reach a lateral resolution of 1 µm on an area of 233 × 233 µm, thus approaching the typical size of microbial cells. The mappings showed different ‘provenances’ within the sections that are distinguished by individual lipid fingerprints, namely (A) the diethers archaeol and hydroxyarchaeol co‐occurring with glycerol dialkyl glycerol tetraethers (GDGT), (B) hydroxyarchaeol and dihydroxyarchaeol, and (C) GDGT and gentiobiosyl‐GDGT. Because ToF‐SIMS is a virtually nondestructive technique affecting only the outermost layers of the sample surface (typically 10–100 nm), it was possible to further examine the studied areas using conventional microscopy, and associate the individual lipid patterns with specific morphological traits. This showed that provenance (B) was frequently associated with irregular, methane‐derived CaCO3 crystallites, whereas provenance (C) revealed a population of fluorescent, filamentous microorganisms showing the morphology of known methanotrophic ANME‐1 archaea. The direct coupling of imaging mass spectrometry with microscopic techniques reveals interesting perspectives for the in‐situ study of lipids in geobiology, microbial ecology, and organic geochemistry. After further developing protocols for handling different kinds of environmental samples, ToF‐SIMS could be used as a tool to attack many challenging problems in these fields, such as the attribution of biological source(s) to particular biomarkers in question, or the high‐resolution tracking of biogeochemical processes in modern and ancient natural environments.

Analysis of archaeal core ether lipids using Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS): Exploring a new prospect for the study of biomarkers in geobiology.

The capability of Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) of analysing molecular archaeal biomarkers in geobiological samples was tested and demonstrated. Using a bismuth cluster primary ion source, isopranyl glycerol di- and tetraether core lipids were detected in small amounts of total organic extracts from methanotrophic microbial mats, simultaneously and without further chemical treatment and chromatographic separation. ToF-SIMS was also employed to track the distribution of fossilized ether lipids in a massive carbonate (aragonite) microbialite that precipitated as a result of the microbial anaerobic oxidation of methane. An unambiguous signal was obtained when analysing a freshly broken rock surface (base of a microdrill core). Though some limitation occurred due to µm-topographical effects (sample roughness), it was possible to display the abundance of high molecular weight (C86 ) of tetraethers exposed in particular regions of the rock surface. 'Molecular mapping' revealed that a part of these molecules was encased within the rock fabric in a cluster-like distribution that might trace the arrangement of the calcifying microbial colonies in the once active mat system. The results reveal promising perspectives of ToF-SIMS for (i) the quasi-nondestructive analysis of lipids in extremely small geobiological samples at low concentrations; (ii) resolving the spatial distribution of these compounds on a µm2 - to cm2 -scale; and (iii) the more exact assignment of lipid biomarkers to their biological source.

Evaluation of secondary ion yield enhancement from polymer material by using TOF-SIMS equipped with a gold cluster ion source

We investigated the enhancement of the secondary ion intensity in the TOF-SIMS spectra obtained by Au + and Au 3 + bombardment in comparison with Ga + excitation using polymer samples with different molecular weight distributions. Since the polymer samples used in this experiment have a wide molecular weight distribution, the advantages of the gold cluster primary ion source over monoatomic ion could accurately be evaluated. It was observed that the degree of fragmentation decreased by the usage of cluster primary ion beam compared with monoatomic ion beam, which was observed as a shift of the intensity distribution in the spectra. It was also found out that the mass effect of Au + and Ga + as monoatomic primary ion, resulted in about 10–60 times of enhancement for both samples with different molecular distributions. On the other hand, the Au 3 + bombardment caused intensity enhancement about 100–2600 compared with Ga + bombardment, depending on the mass range of the detected secondary ion species. The cluster primary ion effect of Au 3 +, compared with Au +, therefore, was estimated to be about 10–45.

Auクラスター一次イオン源を用いたTOF-SIMS測定における二次イオン強度増大効果

Enhancement of the secondary ion intensity in the TOF-SIMS spectra obtained by Au+ and Au3+ bombardment was investigated in comparison with Ga+ excitation using polymer samples with different molecular weight distributions. Since the polymer samples used in this experiment have wide molecular weight distributions, the advantages of a gold cluster primary ion source over a monoatomic ion source could systematically be evaluated. It was found that a Au primary ion source for a TOF-SIMS instrument has advantages in such terms as (1) the mass effect of the monoatomic primary ion, i.e., Au+ vs. Ga+, (2) the cluster primary ion effect of Au3+ compared with Au+ and Ga+, and (3)decrease in the degree of fragmentation by usage of a cluster primary ion beam compared with a monoatomic ion beam.

Secondary Ion MS Imaging of Lipids in Picoliter Vials with a Buckminsterfullerene Ion Source

Investigation of the spatial distribution of lipids in cell membranes can lead to an improved understanding of the role of lipids in biological function and disease. Time-of-flight secondary ion mass spectrometry is capable of molecule-specific imaging of biological molecules across single cells and has demonstrated potential for examining the functional segregation of lipids in cell membranes. In this paper, standard SIMS spectra are analyzed for phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine, phosphatidylinositol, cholesterol, and sulfatide. Importantly, each of the lipids result in signature mass spectral peaks that allow them to be identified. These signature peaks are also useful for imaging experiments and are utilized here to simultaneously image lipids on a micrometer scale in picoliter vials. Because the low secondary ion signal achieved for lipids from an atomic primary ion source makes cell-imaging experiments challenging, improving signal with cluster primary ion sources is of interest. Here, we compare the secondary ion yield for seven lipids using atomic (Ga+ or In+) ion sources and a buckminsterfullerene (C60+) primary ion source. A 40-1000-fold improvement in signal is found with C60+ relative to the other two ion sources, indicating great promise for future cellular imaging applications using the C60+ probe.