TY - JOUR A1 - Bakirci, Ezgi A1 - Frank, Andreas A1 - Gumbel, Simon A1 - Otto, Paul F. A1 - Fürsattel, Eva A1 - Tessmer, Ingrid A1 - Schmidt, Hans‐Werner A1 - Dalton, Paul D. T1 - Melt Electrowriting of Amphiphilic Physically Crosslinked Segmented Copolymers JF - Macromolecular Chemistry and Physics N2 - Various (AB)\(_{n}\) and (ABAC)\(_{n}\) segmented copolymers with hydrophilic and hydrophobic segments are processed via melt electrowriting (MEW). Two different (AB)\(_{n}\) segmented copolymers composed of bisurea segments and hydrophobic poly(dimethyl siloxane) (PDMS) or hydrophilic poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEG-PPO) segments, while the amphiphilic (ABAC)\(_{n}\) segmented copolymers consist of bisurea segments in the combination of hydrophobic PDMS segments and hydrophilic PPO-PEG-PPO segments with different ratios, are explored. All copolymer compositions are processed using the same conditions, including nozzle temperature, applied voltage, and collector distance, while changes in applied pressure and collector speed altered the fiber diameter in the range of 7 and 60 µm. All copolymers showed excellent processability with MEW, well-controlled fiber stacking, and inter-layer bonding. Notably, the surfaces of all four copolymer fibers are very smooth when visualized using scanning electron microscopy. However, the fibers show different roughness demonstrated with atomic force microscopy. The non-cytotoxic copolymers increased L929 fibroblast attachment with increasing PDMS content while the different copolymer compositions result in a spectrum of physical properties. KW - melt electrowriting KW - 3D printing KW - additive manufacturing KW - electrohydrodynamics Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257572 VL - 222 IS - 22 ER - TY - JOUR A1 - Kade, Juliane C. A1 - Otto, Paul F. A1 - Luxenhofer, Robert A1 - Dalton, Paul D. T1 - Melt electrowriting of poly(vinylidene difluoride) using a heated collector JF - Polymers for Advanced Technologies N2 - Previous research on the melt electrowriting (MEW) of poly(vinylidene difluoride) (PVDF) resulted in electroactive fibers, however, printing more than five layers is challenging. Here, we investigate the influence of a heated collector to adjust the solidification rate of the PVDF jet so that it adheres sufficiently to each layer. A collector temperature of 110°C is required to improve fiber processing, resulting in a total of 20 fiber layers. For higher temperatures and higher layers, an interesting phenomenon occurred, where the intersection points of the fibers coalesced into periodic spheres of diameter 206 ± 52 μm (26G, 150°C collector temperature, 2000 mm/min, 10 layers in x- and y-direction).The heated collector is an important component of a MEW printer that allows polymers with a high melting point to be processable with increased layers. KW - additive manufacturing KW - polymer processing KW - melt electrowriting KW - electroactive Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-318493 SN - 1042-7147 VL - 32 IS - 12 SP - 4951 EP - 4955 ER - TY - JOUR A1 - Huss, André M. A1 - Halbgebauer, Steffen A1 - Öckl, Patrick A1 - Trebst, Corinna A1 - Spreer, Annette A1 - Borisow, Nadja A1 - Harrer, Andrea A1 - Brecht, Isabel A1 - Balint, Bettina A1 - Stich, Oliver A1 - Schlegel, Sabine A1 - Retzlaff, Nele A1 - Winkelmann, Alexander A1 - Roesler, Romy A1 - Lauda, Florian A1 - Yildiz, Özlem A1 - Voß, Elke A1 - Muche, Rainer A1 - Rauer, Sebastian A1 - Bergh, Florian Then A1 - Otto, Markus A1 - Paul, Friedemann A1 - Wildemann, Brigitte A1 - Kraus, Jörg A1 - Ruprecht, Klemens A1 - Stangel, Martin A1 - Buttmann, Mathias A1 - Zettl, Uwe K. A1 - Tumani, Hayrettin T1 - Importance of cerebrospinal fluid analysis in the era of McDonald 2010 criteria: a German-Austrian retrospective multicenter study in patients with a clinically isolated syndrome JF - Journal of Neurology N2 - The majority of patients presenting with a first clinical symptom suggestive of multiple sclerosis (MS) do not fulfill the MRI criteria for dissemination in space and time according to the 2010 revision of the McDonald diagnostic criteria for MS and are thus classified as clinically isolated syndrome (CIS). To re-evaluate the utility of cerebrospinal fluid (CSF) analysis in the context of the revised McDonald criteria from 2010, we conducted a retrospective multicenter study aimed at determining the prevalence and predictive value of oligoclonal IgG bands (OCBs) in patients with CIS. Patients were recruited from ten specialized MS centers in Germany and Austria. We collected data from 406 patients; at disease onset, 44/406 (11 %) fulfilled the McDonald 2010 criteria for MS. Intrathecal IgG OCBs were detected in 310/362 (86 %) of CIS patients. Those patients were twice as likely to convert to MS according to McDonald 2010 criteria as OCB-negative individuals (hazard ratio = 2.1, p = 0.0014) and in a shorter time period of 25 months (95 % CI 21-34) compared to 47 months in OCB-negative individuals (95 % CI 36-85). In patients without brain lesions at first attack and presence of intrathecal OCBs (30/44), conversion rate to MS was 60 % (18/30), whereas it was only 21 % (3/14) in those without OCBs. Our data confirm that in patients with CIS the risk of conversion to MS substantially increases if OCBs are present at onset. CSF analysis definitely helps to evaluate the prognosis in patients who do not have MS according to the revised McDonald criteria. KW - multiple sklerosis KW - MRI criteria KW - conversion KW - MS KW - CSF KW - biomarker KW - OCB Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-186619 VL - 263 IS - 12 ER - TY - JOUR A1 - Renner, Tobias A1 - Otto, Paul A1 - Kübler, Alexander C. A1 - Hölscher-Doht, Stefanie A1 - Gbureck, Uwe T1 - Novel adhesive mineral-organic bone cements based on phosphoserine and magnesium phosphates or oxides JF - Journal of Materials Science: Materials in Medicine N2 - Present surgical situations require a bone adhesive which has not yet been developed for use in clinical applications. Recently, phosphoserine modified cements (PMC) based on mixtures of o-phosphoserine (OPLS) and calcium phosphates, such as tetracalcium phosphate (TTCP) or α-tricalcium phosphate (α-TCP) as well as chelate setting magnesium phosphate cements have gained increasing popularity for their use as mineral bone adhesives. Here, we investigated new mineral-organic bone cements based on phosphoserine and magnesium phosphates or oxides, which possess excellent adhesive properties. These were analyzed by X-ray diffraction, Fourier infrared spectroscopy and electron microscopy and subjected to mechanical tests to determine the bond strength to bone after ageing at physiological conditions. The novel biomineral adhesives demonstrate excellent bond strength to bone with approximately 6.6–7.3 MPa under shear load. The adhesives are also promising due to their cohesive failure pattern and ductile character. In this context, the new adhesive cements are superior to currently prevailing bone adhesives. Future efforts on bone adhesives made from phosphoserine and Mg2+ appear to be very worthwhile. Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-357342 VL - 34 ER -