-
[show abstract]
[hide abstract]
ABSTRACT: The aim of this contribution is the application of matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) in the area of photolithographic structuring. As proof of concept, this method was used to image an UV exposed negative photoresist layer, which is generally used to manufacture printed circuit boards (PCB) for electronic components. The negative photoresist layer consisting of the main component novolac, benzophenone as the active component, and the solvent tetrahydrofuran was mixed with the matrix dithranol and the salt additive LiTFA and spin-coated onto an ITO-conductive glass slide. To imprint an image on the created surface, a transparency with a printed wiring diagram was placed on top of it and irradiated by UV light for 15 min. The inspection of the efficient imprinting of the microstructure onto the photoresist layer was performed by MALDI-MSI. This unique application represents a further step toward the surface analysis of polymer films by this emerging life science imaging technique.
Analytical Chemistry 07/2012; 84(16):6921-5. · 5.86 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: An electrospray ionization quadrupole time-of-flight mass spectrometer has been utilized to investigate the relative ligand-binding strengths in a series of heteroleptic-charged iridium(III) complexes of the general formula [(C^N)(2) Ir(III) (S-tpy)](PF(6) ) by using variable collision energies. Collision-induced dissociation experiments were performed in order to study the stability of the Ir(III) complexes that are, for instance, suitable phosphors in light-emitting electrochemical cells. The ratio of signal intensities belonging to the fragment and the undissociated complex depends on the collision energy applied for the tandem mass spectra (MS/MS) analysis. By defining the threshold collision energy and the point of complete complex dissociation, it is possible to estimate the relative complex stabilities depending on the nature of the coordinated ligands [i.e. type of cyclometalating ligand (C^N), substituents on the S-shaped terpyridine (S-tpy)]. The collision energy values differed as a function of the coordination sphere of the Ir(III) centers.
Biological Mass Spectrometry 01/2012; 47(1):34-40. · 3.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: In this contribution, linear poly(ethylene imine) (PEI) polymers, which are of importance in gene delivery, are investigated in detail by using electrospray ionization-quadrupole-time of flight (ESI-Q-TOF) and matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (MS). The analyzed PEIs with different end groups were synthesized using the polymerization of substituted 2-oxazoline via a living cationic ring-opening polymerization (CROP) and a subsequent hydrolysis under acidic conditions. The main goal of this study was to identify linear PEI polymers in a detailed way to gain information about their fragmentation pathways. For this purpose, a detailed characterization of three different linear PEIs was performed by using ESI-Q-TOF and MALDI-TOF MS in combination with collision-induced dissociation (CID) experiments. In ESI-MS as well as MALDI-MS analysis, the obtained spectra of PEIs resulted in fitting mass distributions for the investigated PEIs. In the tandem MS analysis, a 1,2-hydride shift with a charge-remote rearrangement via a four-membered cyclic transition state, as well as charge-induced fragmentation reactions, was proposed as the main fragmentation mechanisms according to the obtained fragmentation products from the protonated parent peaks. In addition, heterolytic and homolytic cleavages were proposed as alternative fragmentation pathways. Moreover, a 1,4-hydrogen elimination was proposed to explain different fragmentation products obtained from the sodiated parent peaks.
Biological Mass Spectrometry 01/2012; 47(1):105-14. · 3.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This study presents the application of matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI) to monitor changes occurring at polymer surfaces. As an example, a poly(styrene) (PS) film was irradiated with ultraviolet (UV) light at 254 nm for different time intervals, while areas of the film were protected from UV light by covering it with an aluminum mask. After the UV treatment, the polymer surface was analyzed by MALDI-MSI. Time-dependent photo-induced cross-linking of the polymer film was observed, and a correlation curve between UV radiation time and area of cross-linking was constructed. This represents the first step towards the surface analysis of polymer components of photoresists and top coatings of cars, and it will also enable a new characterization strategy for combinatorial material research.
Rapid Communications in Mass Spectrometry 10/2011; 25(19):2809-14. · 2.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The manual interpretation of tandem mass spectra of synthetic polymers is very time-consuming. Therefore, a new software tool was developed to accelerate the interpretation of spectra obtained without requiring any further knowledge about the polymer class or the fragmentation behavior under high-energy collision-induced dissociation (CID) conditions. The software only requires an alphabetical list of elements and a peak list of the measured substance as an xml file for the evaluation of the chosen mass spectrum. Tandem mass spectra of different homopolymers, like poly(2-oxazoline)s, poly(ethylene glycol) and poly(styrene), were interpreted by the new software tool. This contribution describes a fast and automated software tool for the rapid analysis of homopolymers.
Rapid Communications in Mass Spectrometry 06/2011; 25(12):1765-78. · 2.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Taking advantage of the drop-on-demand capabilities of inkjet printing, the first example of a single tissue being used as a substrate for preparing combinatorial arrays of different matrix-assisted laser desorption/ionization (MALDI) matrices in multiple concentrations on a single chip is reported. By varying the number of droplets per spot that were printed, a gradient array of different amounts of matrix material could be printed on a single chip, while the selection of matrices could be adjusted by switching different matrix materials. The result was a two-dimensional array of multiple matrices on a single tissue slice, which could be analyzed microscopically and by MALDI to elucidate which combination of matrix and printing conditions offered the best resolution in terms of spot-to-spot distance and signal-to-noise ratios for proteins in the recorded MS spectra. This combinatorial approach enables the efficient optimization of possible matrices in an organized, side-by-side array format, which can particularly be useful for the detection of specific protein markers.
ACS combinatorial science. 03/2011; 13(3):218-22.
-
[show abstract]
[hide abstract]
ABSTRACT: Carcinoma tissue consists of not only tumor cells but also fibroblasts, endothelial cells or vascular structures, and inflammatory cells forming the supportive tumor stroma. Therefore, the spatial distribution of proteins that promote growth and proliferation in these complex functional units is of high interest. Matrix-assisted laser desorption/ionization imaging mass spectrometry is a newly developed technique that generates spatially resolved profiles of protein signals directly from thin tissue sections. Surface-enhanced laser desorption/ionization mass spectrometry (MS)combined with tissue microdissection allows analysis of defined parts of the tissue with a higher sensitivity and a broader mass range. Nevertheless, both MS-based techniques have a limited spatial resolution. IHC is a technique that allows a resolution down to the subcellular level. However, the detection and measurement of a specific protein expression level is possible only by semiquantitative methods. Moreover, prior knowledge about the identity of the proteins of interest is necessary. In this study, we combined all three techniques to gain highest spatial resolution, sensitivity, and quantitative information. We used frozen tissue from head and neck tumors and chose two exemplary proteins (HNP1-3 and S100A8) to highlight the advantages and disadvantages of each technique. It could be shown that the combination of these three techniques results in congruent but also synergetic data.
Journal of Histochemistry and Cytochemistry 10/2010; 58(10):929-37. · 2.72 Impact Factor
-
Journal of Polymer Science Part A Polymer Chemistry 09/2010; 48(20):4375 - 4384. · 3.92 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The detailed characterization of macromolecules plays an important role for synthetic chemists to define and specify the structure and properties of the successfully synthesized polymers. The search for new characterization techniques for polymers is essential for the continuation of the development of improved synthesis methods. The application of tandem mass spectrometry for the detailed characterization of synthetic polymers using the soft ionization techniques matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and electrospray ionization mass spectrometry (ESI-MS), which became the basic tools in proteomics, has greatly been increased in recent years and is summarized in this perspective. Examples of a variety of homopolymers, such as poly(methyl methacrylate), poly(ethylene glycol), as well as copolymers, e.g. copolyesters, are given. The advanced mass spectrometric techniques described in this review will presumably become one of the basic tools in polymer chemistry in the near future.
Biological Mass Spectrometry 09/2009; 44(9):1277-86. · 3.41 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The aim of this study is to compare the proteome of Prnp-/- (Zürich I) gene-ablated mouse brains with wild-type mouse brains. Fluorescence two-dimensional-difference gel electrophoresis (DIGE) and isotope-coded protein labeling (ICPL) were applied for brain homogenates. Similar quantitative protein profiles (<or=1.5-fold change, P<0.05) were obtained by quantitative two-dimensional-DIGE analysis of whole brain homogenates of two developmental stages (days 1 and 67). Complementary ICPL-liquid chromatography-mass spectrometry experiments (n=5) of whole brain homogenates and synaptosomes were performed. The abundance ratios of all proteins quantified did not exceed the statistical spread determined (<2-fold). Therefore, both of the two-dimensional-DIGE and ICPL analyses demonstrated a highly conserved quantitative protein profile in brain homogenates of Prnp-/- and Prnp+/+ mice.
Neuroreport 07/2008; 19(10):1027-31. · 1.66 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Within the Human Proteome Organization (HUPO) Brain Proteome Project, a pilot study was launched with reference samples shipped to nine international laboratories (see Hamacher et al., this Special Issue) to evaluate different proteome approaches in neuroscience and to build up a first version of a brain protein database. One part of the study addresses quantitative proteome alterations between three developmental stages (embryonic day 16; postnatal day 7; 8 weeks) of mouse brains. Five brains per stage were differentially analyzed by 2-D DIGE using internal standardization and overlapping pH gradients (pH 4-7 and 6-9). In total, 214 protein spots showing stage-dependent intensity alterations (> two-fold) were detected, 56 of which were identified. Several of them, e.g. members of the dihydropyrimidinase family, are known to be associated with brain development. To feed the HUPO BPP brain protein database, a robust 2-D LC-MS/MS method was applied to murine postnatal day 7 and human post-mortem brain samples. Using MASCOT and the IPI database, 350 human and 481 mouse proteins could be identified by at least two different peptides. The data are accessible through the PRIDE database (http://www.ebi.ac.uk/pride/).
PROTEOMICS 09/2006; 6(18):4950-66. · 4.51 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We have developed a method to visualize matrix-assisted laser desorption ionization imaging mass spectrometry (MALDI IMS) data aligned with optically determinable tissue structures in three dimensions. Details of the methodology are exemplified using the 3-D reconstruction of myelin basic protein (MBP) in the corpus callosum of a mouse brain. In this procedure, optical images obtained from serial coronal sections are first aligned to each other to reconstruct a surface of the corpus callosum from segmented contours of the aligned images. The MALDI IMS data are then coregistered to the optical images and superimposed into the surface to create the final 3-D visualization. Correlating proteomic data with anatomical structures provides a more comprehensive understanding of healthy and pathological brain functions, and holds promise to be utilized in more complex anatomical arrangements.
Journal of the American Society for Mass Spectrometry 08/2005; 16(7):1093-9. · 4.00 Impact Factor
