Chemical reactions induced in polymers by keV ions, electrons and photons

Marletta, Giovanni; Catalano, Stefano; Pignataro, S.

doi:10.1002/sia.740160185

Cited by 85 publications

(40 citation statements)

References 12 publications

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“…Spectra were taken while maintaining a primary ion dose of 3.3 ð 10 12 ions/cm 2 to ensure static SIMS conditions. 3 Mass resolution (m/m) at the C 4 H 8 N C peak was always greater than 6000. Spectra were collected from three spots on each sample.…”

Section: Tof-simsmentioning

confidence: 99%

Improving the interpretation of ToF‐SIMS measurements on adsorbed proteins using PCA

Brüning

Hellweg

Dambach

et al. 2006

Surface & Interface Analysis

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Analyzing different proteins with time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a big challenge owing to the absence of unique, identifying peaks between the protein spectra. One possibility for improving the interpretation of the protein spectra is the application of principal component analysis (PCA). The proteins fibronectin and collagen and three fibronectin-collagen mixtures, adsorbed on smooth silicon substrates, were analyzed with ToF-SIMS. The intensities of molecular protein fragment signals were used to perform a PCA calculation. It was shown that PCA could clearly distinguish the various protein mixtures. From the loadings, it was possible to draw conclusions about the peak intensity distribution. Furthermore, PCA was found to be an appropriate statistical tool to identify outlier.

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Section: Tof-simsmentioning

confidence: 99%

Improving the interpretation of ToF‐SIMS measurements on adsorbed proteins using PCA

Brüning

Hellweg

Dambach

et al. 2006

Surface & Interface Analysis

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“…The area of analysis for each spectrum was 100 m ϫ 10 m. The total ion dose used to acquire each spectrum was less than 2 ϫ 10 12 ions/cm 2 to ensure static conditions. 12 The mass resolution (m/⌬m) of the secondary ion peaks was typically between 6000 and 9500. At least three replicates were prepared for each sample, with three spectra acquired from each replicate.…”

Section: Tof-simsmentioning

confidence: 99%

Preserving the structure of adsorbed protein films for time‐of‐flight secondary ion mass spectrometry analysis

Xia

Castner

2003

J Biomedical Materials Res

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The characterization of adsorbed protein films with ultrahigh vacuum (UHV) surface analysis techniques requires dehydration of the samples, which can cause significant alterations in protein structure. It is desirable to preserve the structure of adsorbed protein films during drying, so UHV analysis could be done in a state that is more representative of proteins' actual structure in the aqueous environment. In this study, two methods, trehalose protection and glutaraldehyde fixation, were explored for their feasibility in preserving adsorbed protein structure for a powerful UHV surface analysis technique, time-of-flight secondary ion mass spectrometry (ToF-SIMS). Trehalose protection had shown some promise for ToF-SIMS analysis in our previous study and was further examined with the model protein fibrinogen in this study. Using the combination of principal component analysis (PCA) and static ToF-SIMS analysis, we found that trehalose protection could reduce the conformation change of fibrinogen upon drying, and prevent it from unfolding and exposing hydrophobic domains. Moreover, when the adsorbed protein film became more densely packed, the drying-induced changes in protein structure were reduced. Thus, the protection afforded by trehalose coating was more significant at lower protein surface concentrations. The other method, glutaraldehyde fixation, was used in ToF-SIMS analysis for the first time. The epsilon-amino group of lysine was identified as the major reactive group in the protein structure toward glutaraldehyde fixation. Structural differences observed between fibrinogen films that were glutaraldehyde fixed before drying and after drying were similar to those observed between trehalose-protected and-unprotected dried fibrinogen films. Glutaraldehyde fixation was found to be a viable, alternative stabilizing method to trehalose protection for ToF-SIMS analysis.

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“…3(a) includes four parts, TP (69, 70), GM (104, 105), CK (115, 116) and GC (126, 127), out of the six underlined parts in the above sequence. In addition, one of the other two parts MK (11,12) is very close to this site, and the other LC(75, 76) can also be at this site, because it is in the form of a random coil which does not maintain a stable structure. The ribbon diagram of the lysozyme is shown in Fig.…”

Section: Kvf[grc]elaa Amkrhgldny Rgyslgnwvc Aakfesnfnt Qatnrntdgs Tdymentioning

confidence: 94%

“…Positive ion spectra which were obtained with TOF-SIMS to TRIFT-IV (Physical Electronics, Eden Prairie, MN, USA) using 12 keV Ga + and 17 keV C 60 + primary ion sources, were acquired at up to 1000 m/z while maintaining the primary ion dose at less than 10 12 ions/cm 2 to ensure static conditions [11] All the spectra were calibrated to the CH 3 + , C 2 H 5 + , C 3 H 5 + and C 4 H 7 + peaks before data analysis.…”

Section: Tof-sims Measurementmentioning

confidence: 99%

Investigation of molecular surfaces with time‐of‐flight secondary ion mass spectrometry

Aoyagi

Namekawa

Yamamoto

et al. 2010

Surface & Interface Analysis

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TOF-SIMS is a promising technique for evaluating biodevices due to its ultrahigh surface sensitivity. Since a cluster ion source such as C 60 + provides low collision energy per atom, time-of-flight secondary ion mass spectrometry (TOF-SIMS) with the cluster ion is useful for detecting the uppermost surface of molecules immobilized on a substrate, and therefore, enables the evaluation of the orientation of these immobilized biomolecules. Effects of TOF-SIMS with C 60 + were investigated in this study. A relatively small protein, lysozyme, and polypeptides having five amino acid residues, Leu-enkephalin and Met-enkephalin, were employed as model samples. The protein and the polypeptides were immobilized on aminosilanized-indium-tin oxide (ITO) coated glass plates at their N-terminal residues by covalent bonding. The aminosilanized-ITO plate without protein or polypeptide was also prepared as a control sample. After freeze-drying, the samples were measured with TOF-SIMS using gallium and C 60 + cluster ion sources, and then TOF-SIMS spectra were analyzed to select peaks specific to each biomolecule by a comparison between the samples. As a result, the C 60 + primary ion source showed advantages in evaluating biomolecules, because more peaks at a higher mass generated from the biomolecules can be obtained using C 60 + than Ga + or Au 3 + as the primary ion source, although no difference was detected between the two polypeptide samples under the current measurement conditions.

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Chemical reactions induced in polymers by keV ions, electrons and photons

Cited by 85 publications

References 12 publications

Improving the interpretation of ToF‐SIMS measurements on adsorbed proteins using PCA

Improving the interpretation of ToF‐SIMS measurements on adsorbed proteins using PCA

Preserving the structure of adsorbed protein films for time‐of‐flight secondary ion mass spectrometry analysis

Investigation of molecular surfaces with time‐of‐flight secondary ion mass spectrometry

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