7 results on '"Stepula, Elzbieta"'
Search Results
2. Evaluation of 3D gold nanodendrite layers obtained by templated galvanic displacement reactions for SERS sensing and heterogeneous catalysis
- Author
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Han, Weijia, Stepula, Elzbieta, Philippi, Michael, Schlücker, Sebastian, and Steinhart, Martin
- Subjects
Physics - Applied Physics ,Condensed Matter - Materials Science - Abstract
Dense layers of overlapping three-dimensional (3D) gold nanodendrites characterized by high specific surfaces as well as by abundance of sharp edges and vertices creating high densities of SERS hotspots are promising substrates for SERS-based sensing and catalysis. We have evaluated to what extent structural features of 3D gold nanodendrite layers can be optimized by the initiation of 3D gold nanodendrite growth at gold particles rationally positioned on silicon wafers. For this purpose, galvanic displacement reactions yielding 3D gold nanodendrites were guided by hexagonal arrays of parent gold particles with a lattice constant of 1.5 micrometers obtained by solid-state dewetting of gold on topographically patterned silicon wafers. Initiation of the growth of dendritic features at edges of the gold particles resulted in the formation of 3D gold nanodendrites while limitation of dendritic growth to the substrate plane was prevented. The regular arrangement of the parent gold particles supported the formation of dense layers of overlapping 3D gold nanodendrites that were sufficiently homogeneous within the resolution limits of Raman microscopes. Consequently, SERS mapping experiments revealed a reasonable degree of uniformity. The proposed preparation algorithm comprises only bottom-up process steps that can be carried out without use of costly instrumentation.
- Published
- 2019
- Full Text
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3. Influence of the PAN:PEO Ratio on the Morphology of Needleless Electrospun Nanofiber Mats Before and After Carbonization.
- Author
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Mpofu, Nonsikelelo Sheron, Topuz, Yusuf, Stepula, Elzbieta, Güth, Uwe, Grothe, Timo, Storck, Jan Lukas, Wortmann, Martin, Mahltig, Boris, and Ehrmann, Andrea
- Subjects
ETHYLENE oxide ,POLYMER blends ,POLYMERIC membranes ,SCANNING electron microscopy ,MOLECULAR weights - Abstract
Nanofiber mats with a high surface-to-volume ratio can be prepared by electrospinning. The Porosity is sometimes reported to be tunable by blending different materials, e.g., water-soluble poly(ethylene oxide) (PEO) with not water-soluble poly(acrylonitrile) (PAN). Here, nanofiber mats were electrospun from different PAN:PEO ratios, using a wire-based electrospinning machine "Nanospider Lab". Investigations of the as-spun nanofiber mats as well as of membranes after washing off the water-soluble PEO by scanning electron microscopy (SEM) revealed severe differences in the nanofiber mat morphologies, such as varying fiber diameters and especially non-fibrous areas in the carbonized nanofiber mats, depending on the amount of PEO in the nanofiber mat as well as the molecular weight of the PEO. Similarly, the ratio and molecular weight of PEO influenced the results of stabilization and carbonization. This paper discusses the possibility of tailoring nanofiber porosity for the potential use of PAN nanofiber mats in tissue engineering, filtration, and other applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. ImmunoSERS microscopy for the detection of smooth muscle cells in atherosclerotic plaques
- Author
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Wiercigroch, Ewelina, Stepula, Elzbieta, Mateuszuk, Lukasz, Zhang, Yuying, Baranska, Malgorzata, Chlopicki, Stefan, Schlücker, Sebastian, and Malek, Kamilla
- Published
- 2019
- Full Text
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5. Opto‐Lipidomics of Tissues.
- Author
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Jensen, Magnus, Liu, Shiyue, Stepula, Elzbieta, Martella, Davide, Birjandi, Anahid A., Farrell‐Dillon, Keith, Chan, Ka Lung Andrew, Parsons, Maddy, Chiappini, Ciro, Chapple, Sarah J., Mann, Giovanni E., Vercauteren, Tom, Abbate, Vincenzo, and Bergholt, Mads S.
- Subjects
DESORPTION electrospray ionization ,OPTICAL spectra ,VIBRATIONAL spectra ,LIPID metabolism ,RAMAN scattering ,CEREBRAL arteries - Abstract
Lipid metabolism and signaling play pivotal functions in biology and disease development. Despite this, currently available optical techniques are limited in their ability to directly visualize the lipidome in tissues. In this study, opto‐lipidomics, a new approach to optical molecular tissue imaging is introduced. The capability of vibrational Raman spectroscopy is expanded to identify individual lipids in complex tissue matrices through correlation with desorption electrospray ionization (DESI) – mass spectrometry (MS) imaging in an integrated instrument. A computational pipeline of inter‐modality analysis is established to infer lipidomic information from optical vibrational spectra. Opto‐lipidomic imaging of transient cerebral ischemia‐reperfusion injury in a murine model of ischemic stroke demonstrates the visualization and identification of lipids in disease with high molecular specificity using Raman scattered light. Furthermore, opto‐lipidomics in a handheld fiber‐optic Raman probe is deployed and demonstrates real‐time classification of bulk brain tissues based on specific lipid abundances. Opto‐lipidomics opens a host of new opportunities to study lipid biomarkers for diagnostics, prognostics, and novel therapeutic targets. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Opto‐Lipidomics of Tissues
- Author
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Jensen, Magnus, primary, Liu, Shiyue, additional, Stepula, Elzbieta, additional, Martella, Davide, additional, Birjandi, Anahid A., additional, Farrell‐Dillon, Keith, additional, Chan, Ka Lung Andrew, additional, Parsons, Maddy, additional, Chiappini, Ciro, additional, Chapple, Sarah J., additional, Mann, Giovanni E., additional, Vercauteren, Tom, additional, Abbate, Vincenzo, additional, and Bergholt, Mads S., additional
- Published
- 2023
- Full Text
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7. Immun-SERS-Mikroskopie an einzelnen Zellen
- Author
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Stepula, Elzbieta, Schlücker, Sebastian, and Schlücker, Sebastian (Akademische Betreuung)
- Subjects
ddc:540 ,Chemie ,Fakultät für Chemie » Physikalische Chemie - Abstract
Immuno-SERS microscopy (iSERS) is an emerging immuno-based method for protein localization on cells and tissue sections. Antibodies bind specifically to certain proteins that are expressed in the cells or tissues. The antibodies are labeled with plasmonically active noble metal nanoparticles, which are functionalized with Raman-active molecules. The detection is carried out by surface-enhanced Raman scattering (SERS). In this study, gold/gold core/satellite particles (AuKSP) were used as SERS nanotags, which are conjugated to antibodies. The AuKSP consist of positively charged core and negatively charged satellite particles, which were assembled through electrostatic interactions. AuKSP, consisting of 50 nm core and 20 nm satellites, were separated using Asymmetric Flow-Field Flow Fractionation and analyzed online via light absorption and scattering. At first, a separation method for these nanoparticles was developed and optimized. The analysis of the fractograms, which represent the separation behavior of the nanoparticles, exhibit differences in quality between different batches of nanoparticles. The AuKSP were then functionalized with a polyethylene glycol (PEG) shell and conjugated to antibodies in order to localize the predictive biomarker PD-L1 in single-cell experiments. The expression of PD-L1 in cancer tissue strongly correlates with the patients’ response to immunotherapy with checkpoint inhibitors. The localization of this antigen is therefore of great importance. The binding specificity of the SERS-labeled antibodies was additionally confirmed using a negative control experiment. Finally, a proof-of-concept study was carried out, in which multicolor localization of a protein was demonstrated using iSERS microscopy. First, smaller AuKSP were synthesized (30 + 17 nm) and six different Raman reporter molecules were selected. Six spectrally distinguishable SERS nanotags with a similar SERS signal intensity were synthesized. An antibody (anti-HER2) was conjugated to each of the six different SERS nanotags. Subsequently, the prominent biomarker HER2 could be localized on individual SkBr-3 cells using six different SERS nanotag/anti HER2 antibody conjugates. This study is the first step towards the parallel localisation of several proteins on the same cell or tissue section. Dissertation, Universität Duisburg-Essen, 2020
- Published
- 2020
- Full Text
- View/download PDF
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