37 research outputs found

    Characterization of Polymer Membranes by MALDI Mass-Spectrometric Imaging Techniques

    No full text
    For physical and chemical characterization of polymers, a wide range of analytical methods is available. Techniques like NMR and X-ray are often combined for a detailed characterization of polymers used in medical applications. Over the past few years, MALDI mass-spectrometry has been developed as a powerful tool for space-resolved analysis, not least because of its mass accuracy and high sensitivity. MALDI imaging techniques combine the potential of mass-spectrometric analysis with imaging as additional spatial information. MALDI imaging enables the visualization of localization and distribution of biomolecules, chemical compounds, and other molecules on different surfaces. In this study, surfaces of polymeric dialyzer membranes, consisting of polysulfone (PS) and polyvinylpyrrolidone (PVP), were investigated, regarding chemical structure and the compound’s distribution. Flat membranes as well as hollow fiber membranes were analyzed by MALDI imaging. First, analysis parameters like laser intensity and laser raster step size (spatial resolution in resulting image) were established in accordance with polymer’s characteristics. According to the manufacturing process, luminal and abluminal membrane surfaces are characterized by differences in chemical composition and physical characteristics. The MALDI imaging demonstrated that the abluminal membrane surface consists more of polysulfone than polyvinylpyrrolidone, and the luminal membrane surface displayed more PVP than PS. The addition of PVP as hydrophilic modifier to polysulfone-based membranes increases the biocompatibility of the dialysis membranes. The analysis of polymer distribution is a relevant feature for characterization of dialysis membranes. In conclusion, MALDI imaging is a powerful technique for polymer membrane analysis, regarding not only detection and identification of polymers but also localization and distribution in membrane surfaces

    Linearity results of A) SPARC and B) PR3.

    No full text
    <p>For each biomarker a high concentration sample was serially diluted and theoretical values were compared to the experimental.</p

    Validation of the “<i>artificial artery</i>” as <i>in vitro</i> co-culture system with arterial functional characteristics mimicking <i>in vivo</i> conditions of the vasculature.

    No full text
    <p>Semi-quantitative RT-PCR analysis showing the total VWF mRNA expression in co-colonized HUVECs and HUASMCs. RNA of both cell types was isolated separately. The expression of VWF in 0.1 N/m<sup>2</sup> stimulated HUVECs was taken as reference. (<b>A</b>) MALDI mass spectrum from supernatants of the “<i>artificial artery”</i> after each day. Randomly selected peptides show constant molecular mass-signal intensities over a period of five days (abscissa: relative molecular mass m/z, z = 1; ordinate: relative intensity, arbitrary units). (<b>B</b>) MALDI mass spectrum of the supernatant of endothelial cells after stimulation with 3.0 N/m<sup>2</sup> (upper spectrum) and without stimulation (0.1 N/m<sup>2</sup>) (lower spectrum) (abscissa: relative molecular mass, m/z, z = 1; ordinate: relative intensity, arbitrary units). (<b>C</b>) Relative mass-signal intensities of Up<sub>4</sub>A in secretomes isolated from HUVECs, HUASMCs, and HUVEC/HUASMC co-cultures in the “<i>artificial artery</i>” after stimulating with 3 N/m<sup>2</sup> for five days. (<b>D</b>) Semi-quantitative RT-PCR analyses showing the total mRNA expression of KLF2, TIMP1, and CCND1 in co-colonized HUVECs exposed to 3 N/m<sup>2</sup> for five days. The expression of each gene in 0.1 N/m<sup>2</sup> stimulated HUVECs was taken as reference. (<b>E</b>) Semi-quantitative RT-PCR analysis showing the total EDN1 mRNA expression in co-colonized HUVECs (0.1 N/m<sup>2</sup> vs. 3 N/m<sup>2</sup>) and HUASMCs (0.1 N/m<sup>2</sup> vs. 3 N/m<sup>2</sup>). The expression of END1 in 0.1 N/m<sup>2</sup> stimulated HUVECs was taken as reference.</p

    Hoechst 33342 staining of human primary cell nuclei colonized onto polypropylene hollow fiber membranes.

    No full text
    <p>(<b>A</b>) Longitudinal section of the inside of a hollow fiber membrane confluently colonized with HUVECs and stained with Hoechst 33342 after 0.1 N/m<sup>2</sup> applied for 24 h (magnification: 1∶100). (<b>B</b>) Longitudinal section of the outside of a HUASMC mono-culture module stimulated with low laminar FSS for 24 h (magnification: 1∶100). (<b>C</b>) Cross-section of a polypropylene hollow fiber co-colonized with HUVECs and HUASMCs. In focus are HUVECs on the inside upon 0.1 N/m<sup>2</sup> applied for five days (magnification: 1∶100). (<b>D</b>) Cross-section of a co-culture module showing HUASMCs on the outside of a hollow fiber after low laminar FSS stimulation for five days (magnification: 1∶100).</p

    Morphological pictures of HUVEC/HUASMC co-cultures upon physiological FSS conditions.

    No full text
    <p>(<b>A</b>) Scanning electron microscopy picture of the homogenously colonized inside of a hollow fiber with confluently grown and characteristically cobblestone shaped human primary endothelial cells upon the application of low laminar FSS (0.1 N/m<sup>2</sup>) for 24 h (magnification: 1∶500). (<b>B</b>) Scanning electron microscopy picture of HUASMCs on the hollow fiber outside with their typical cell cytoskeletal structure and morphology upon 0.1 N/m<sup>2</sup> applied for 24 h (magnification: 1∶400). (<b>C</b>) Confocal microscopic immunolocalization of Cadherin-5 in co-cultivated HUVECs exposed to low laminar FSS (0.1 N/m<sup>2</sup>) over a period of five days (magnification: 1∶400). (<b>D</b>)Cadherin-5 in HUVECs upon high laminar FSS (3 N/m<sup>2</sup>) (magnification: 1∶400). (<b>E</b>) Confocal microscopic immunolocalization of α-smooth-muscle-actin in co-cultivated HUASMCs upon 3 N/m<sup>2</sup> luminally applied for a five day period (magnification: 1∶400). (<b>F</b>) α-smooth-muscle-actin in co-cultivated HUASMCs upon high laminar FSS (3 N/m<sup>2</sup>) (magnification: 1∶400).</p
    corecore