The Experts below are selected from a list of 159 Experts worldwide ranked by ideXlab platform
Andreas Lendlein - One of the best experts on this subject based on the ideXlab platform.
-
poly ethylene glycol grafting to poly ether imide membranes influence on protein adsorption and Thrombocyte Adhesion
Macromolecular Bioscience, 2013Co-Authors: Axel T. Neffe, Toralf Roch, Friedrich Jung, Klaus Richau, Steffen Braune, Maik Von Ruestenlange, Karola Luetzow, Andreas LendleinAbstract:The chain length and end groups of linear PEG grafted on smooth surfaces is known to influence protein adsorption and Thrombocyte Adhesion. Here, it is explored whether established structure function relationships can be transferred to application relevant, rough surfaces. Functionalization of poly(ether imide) (PEI) membranes by grafting with monoamino PEG of different chain lengths (M-n=1kDa or 10kDa) and end groups (methoxy or hydroxyl) is proven by spectroscopy, changes of surface hydrophilicity, and surface shielding effects. The surface functionalization does lead to reduction of adsorption of BSA, but not of fibrinogen. The Thrombocyte Adhesion is increased compared to untreated PEI surfaces. Conclusively, rough instead of smooth polymer or gold surfaces should be investigated as relevant models.
-
surface functionalization of poly ether imide membranes with linear methylated oligoglycerols for reducing thrombogenicity
Macromolecular Rapid Communications, 2012Co-Authors: Maik Lange, Friedrich Jung, Axel T. Neffe, Klaus Richau, Steffen Braune, Karola Luetzow, Nico Scharnagl, Marie Weinhart, Rainer Haag, Andreas LendleinAbstract:Materials for biomedical applications are often chosen for their bulk properties. Other requirements such as a hemocompatible surface shall be fulfilled by suitable chemical functionalization. Here we show, that linear, side-chain methylated oligoglycerols (OGMe) are more stable to oxidation than oligo(ethylene glycol) (OEG). Poly(ether imide) (PEI) membranes functionalized with OGMes perform at least as good as, and partially better than, OEG functionalized PEI membranes in view of protein resistance as well as Thrombocyte Adhesion and activation. Therefore, OGMes are highly potent surface functionalizing molecules for improving the hemocompatibility of polymers.
-
effect of cytochrome p450 dependent epoxyeicosanoids on ristocetin induced Thrombocyte aggregation
Clinical Hemorheology and Microcirculation, 2012Co-Authors: F Jung, Andreas Lendlein, Christian Schulz, F Blaschke, Dominik N Muller, C Mrowietz, R P Franke, Wolfhagen SchunckAbstract:Epoxyeicosatrienoic acids (EETs) produced by cytochrome P450 (CYP)-dependent epoxidation of arachidonic acid (AA) inhibit Thrombocyte Adhesion to the vascular wall. Upon dietary omega-3 fatty acid supplementation, EETs are partially replaced by eicosapentaenoic acid (EPA)-derived epoxyeicosatetraenoic acids (EEQs) and docosahexaenoic acid (DHA)-derived epoxydocosapentaenoic acids (EDPs). We hypothesized that the omega-3 epoxy-metabolites may exhibit superior anti-thrombogenic properties compared to their AA-derived counterparts. To test this hypothesis, we analyzed the effects of 11,12-EET, 17,18-EEQ and 19,20-EDP on Ristocetin-induced Thrombocyte aggregation (RITA), a process that mimics Thrombocyte Adhesion to the vascular wall. The eicosanoids were added for 5, 30, or 60 minutes to Thrombocyte-rich plasma freshly prepared immediately after blood collection from stringently selected apparently healthy subjects. Thrombocyte aggregation was then induced by Ristocetin (0.75 mg/mL) and assessed by turbidimetric measurements. After 60 minutes of preincubation, all three epoxy-metabolites significantly decreased the rate of RITA. 17,18-EEQ and 19,20-EDP were effective already at 1 μM, whereas 5-fold higher concentrations were required with 11,12-EET. Addition of AUDA, an inhibitor of the soluble epoxide hydrolase, potentiated the effect of 17,18-EEQ resulting in a significant further decrease of the velocity as well as amplitude of the aggregation process. In contrast to their profound effects on RITA, none of the epoxy-metabolites was effective in reducing collagen- or ADP-induced Thrombocyte aggregation. These results indicate a highly specific role of CYP-eicosanoids in preventing thromboembolic events and suggest that the formation of 17,18-EEQ and 19,20-EDP may contribute to the anti-thrombotic effects of omega-3 fatty acids.
Axel T. Neffe - One of the best experts on this subject based on the ideXlab platform.
-
Multivalent grafting of hyperbranched oligo- and polyglycerols shielding rough membranes to mediate hemocompatibility.
Journal of materials chemistry. B, 2014Co-Authors: Axel T. Neffe, Maik Von Ruesten-lange, Karola Lützow, Toralf Roch, Tobias Becherer, Andreas F Thunemann, Anne Kruger, Klaus Richau, Steffen Braune, Friedrich JungAbstract:Hemocompatible materials are needed for internal and extracorporeal biomedical applications, which should be realizable by reducing protein and Thrombocyte Adhesion to such materials. Polyethers have been demonstrated to be highly efficient in this respect on smooth surfaces. Here, we investigate the grafting of oligo- and polyglycerols to rough poly(ether imide) membranes as a polymer relevant to biomedical applications and show the reduction of protein and Thrombocyte Adhesion as well as Thrombocyte activation. It could be demonstrated that, by performing surface grafting with oligo- and polyglycerols of relatively high polydispersity (>1.5) and several reactive groups for surface anchoring, full surface shielding can be reached, which leads to reduced protein adsorption of albumin and fibrinogen. In addition, adherent Thrombocytes were not activated. This could be clearly shown by immunostaining adherent proteins and analyzing the Thrombocyte covered area. The presented work provides an important strategy for the development of application relevant hemocompatible 3D structured materials.
-
poly ethylene glycol grafting to poly ether imide membranes influence on protein adsorption and Thrombocyte Adhesion
Macromolecular Bioscience, 2013Co-Authors: Axel T. Neffe, Toralf Roch, Friedrich Jung, Klaus Richau, Steffen Braune, Maik Von Ruestenlange, Karola Luetzow, Andreas LendleinAbstract:The chain length and end groups of linear PEG grafted on smooth surfaces is known to influence protein adsorption and Thrombocyte Adhesion. Here, it is explored whether established structure function relationships can be transferred to application relevant, rough surfaces. Functionalization of poly(ether imide) (PEI) membranes by grafting with monoamino PEG of different chain lengths (M-n=1kDa or 10kDa) and end groups (methoxy or hydroxyl) is proven by spectroscopy, changes of surface hydrophilicity, and surface shielding effects. The surface functionalization does lead to reduction of adsorption of BSA, but not of fibrinogen. The Thrombocyte Adhesion is increased compared to untreated PEI surfaces. Conclusively, rough instead of smooth polymer or gold surfaces should be investigated as relevant models.
-
surface functionalization of poly ether imide membranes with linear methylated oligoglycerols for reducing thrombogenicity
Macromolecular Rapid Communications, 2012Co-Authors: Maik Lange, Friedrich Jung, Axel T. Neffe, Klaus Richau, Steffen Braune, Karola Luetzow, Nico Scharnagl, Marie Weinhart, Rainer Haag, Andreas LendleinAbstract:Materials for biomedical applications are often chosen for their bulk properties. Other requirements such as a hemocompatible surface shall be fulfilled by suitable chemical functionalization. Here we show, that linear, side-chain methylated oligoglycerols (OGMe) are more stable to oxidation than oligo(ethylene glycol) (OEG). Poly(ether imide) (PEI) membranes functionalized with OGMes perform at least as good as, and partially better than, OEG functionalized PEI membranes in view of protein resistance as well as Thrombocyte Adhesion and activation. Therefore, OGMes are highly potent surface functionalizing molecules for improving the hemocompatibility of polymers.
Friedrich Jung - One of the best experts on this subject based on the ideXlab platform.
-
Multivalent grafting of hyperbranched oligo- and polyglycerols shielding rough membranes to mediate hemocompatibility.
Journal of materials chemistry. B, 2014Co-Authors: Axel T. Neffe, Maik Von Ruesten-lange, Karola Lützow, Toralf Roch, Tobias Becherer, Andreas F Thunemann, Anne Kruger, Klaus Richau, Steffen Braune, Friedrich JungAbstract:Hemocompatible materials are needed for internal and extracorporeal biomedical applications, which should be realizable by reducing protein and Thrombocyte Adhesion to such materials. Polyethers have been demonstrated to be highly efficient in this respect on smooth surfaces. Here, we investigate the grafting of oligo- and polyglycerols to rough poly(ether imide) membranes as a polymer relevant to biomedical applications and show the reduction of protein and Thrombocyte Adhesion as well as Thrombocyte activation. It could be demonstrated that, by performing surface grafting with oligo- and polyglycerols of relatively high polydispersity (>1.5) and several reactive groups for surface anchoring, full surface shielding can be reached, which leads to reduced protein adsorption of albumin and fibrinogen. In addition, adherent Thrombocytes were not activated. This could be clearly shown by immunostaining adherent proteins and analyzing the Thrombocyte covered area. The presented work provides an important strategy for the development of application relevant hemocompatible 3D structured materials.
-
poly ethylene glycol grafting to poly ether imide membranes influence on protein adsorption and Thrombocyte Adhesion
Macromolecular Bioscience, 2013Co-Authors: Axel T. Neffe, Toralf Roch, Friedrich Jung, Klaus Richau, Steffen Braune, Maik Von Ruestenlange, Karola Luetzow, Andreas LendleinAbstract:The chain length and end groups of linear PEG grafted on smooth surfaces is known to influence protein adsorption and Thrombocyte Adhesion. Here, it is explored whether established structure function relationships can be transferred to application relevant, rough surfaces. Functionalization of poly(ether imide) (PEI) membranes by grafting with monoamino PEG of different chain lengths (M-n=1kDa or 10kDa) and end groups (methoxy or hydroxyl) is proven by spectroscopy, changes of surface hydrophilicity, and surface shielding effects. The surface functionalization does lead to reduction of adsorption of BSA, but not of fibrinogen. The Thrombocyte Adhesion is increased compared to untreated PEI surfaces. Conclusively, rough instead of smooth polymer or gold surfaces should be investigated as relevant models.
-
surface functionalization of poly ether imide membranes with linear methylated oligoglycerols for reducing thrombogenicity
Macromolecular Rapid Communications, 2012Co-Authors: Maik Lange, Friedrich Jung, Axel T. Neffe, Klaus Richau, Steffen Braune, Karola Luetzow, Nico Scharnagl, Marie Weinhart, Rainer Haag, Andreas LendleinAbstract:Materials for biomedical applications are often chosen for their bulk properties. Other requirements such as a hemocompatible surface shall be fulfilled by suitable chemical functionalization. Here we show, that linear, side-chain methylated oligoglycerols (OGMe) are more stable to oxidation than oligo(ethylene glycol) (OEG). Poly(ether imide) (PEI) membranes functionalized with OGMes perform at least as good as, and partially better than, OEG functionalized PEI membranes in view of protein resistance as well as Thrombocyte Adhesion and activation. Therefore, OGMes are highly potent surface functionalizing molecules for improving the hemocompatibility of polymers.
Ursula Rauen - One of the best experts on this subject based on the ideXlab platform.
-
improvement of the cold storage of blood vessels with a vascular preservation solution study in porcine aortic segments
Journal of Vascular Surgery, 2008Co-Authors: Timo Wille, Herbert De Groot, Ursula RauenAbstract:Background Cold-induced injury to various cell types has been shown to be mediated predominantly by chelatable iron. For endothelial cells, this type of injury has so far only been shown in cultured cells. Hypothesizing that this iron-dependent cold-induced injury might also occur in the endothelium of intact vessels, we here set out to optimize the hypothermic storage of blood vessels. Methods Segments of porcine aorta were stored for 2 to 21 days in histidine-tryptophan-ketoglutarate (HTK) solution or in modified solutions with or without the iron chelators deferoxamine or LK 614 at 4°C. Parts of the segments were assayed immediately after cold storage, the other parts after subsequent rewarming. The percentage of dead (propidium iodide-positive) endothelial cells was assessed by "intravital" fluorescence microscopy, mitochondrial membrane potential was assessed by laser scanning microscopy after staining with tetramethylrhodamine methyl ester (TMRM) and Thrombocyte Adhesion was studied using 5-(and -6)-carboxy SNARF-1-stained Thrombocytes. Results The endothelium of porcine aortic segments sustained moderate injury during the cold incubation itself, but major injury during rewarming. The addition of the iron chelator deferoxamine (1 mmol/L) significantly inhibited cold-induced endothelial cell injury irrespective of the solution used for cold storage (eg, 14 days of cold storage + 3 hours rewarming: HTK 66 ± 7%, HTK + 1 mmol/L deferoxamine 40 ± 10% propidium iodide-positive endothelial cells). An amino acid (glycine, alanine, aspartate)-containing base solution with N-acetylhistidine as buffer was optimized. The optimized base solution with pH 7.0 and potassium and chloride as main ions yielded a further decrease of endothelial cell injury. Combination of deferoxamine (in lower concentration, ie, 0.1 mmol/L) with the new, more membrane-permeable iron chelator LK 614 (20 μmol/L) further improved preservation so that even after 3 weeks of cold storage plus 3 hours rewarming only 10 ± 1% of endothelial cells were propidium iodide positive. In this optimized solution, both endothelial cell survival and mitochondrial membrane potential were significantly better preserved than in the clinically used solutions HTK, University of Wisconsin (UW) and Perfadex, or in physiological saline. Thrombocyte Adhesion was also significantly reduced after cold storage in the optimized solution compared with HTK solution. Conclusion Cold-induced injury to the endothelium of porcine aortic segments is, as the injury to cultured endothelial cells, mediated by chelatable iron. Thus, iron chelators, but also optimized base solutions, are options to improve the storage of vascular endothelium. The optimized solution should now be tested in in vivo animal experiments.
H Reuther - One of the best experts on this subject based on the ideXlab platform.
-
Hemocompatibility of titanium-based coatings prepared by metal plasma immersion ion implantation and deposition
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2007Co-Authors: I Tsyganov, Manfred F Maitz, E Richter, H Reuther, A.i. Mashina, F. RustichelliAbstract:Metal plasma immersion ion implantation and deposition (MePIIID) has been proved to be an effective approach to enhance surface properties of various types of materials. In this work structure, phase composition, microhardness and surface properties, such as wettability and surface energy of layers of the ternary system Ti–N–O produced by MePIIID were investigated. To study the correlation between structure of coating and hemocompatibility the Thrombocyte Adhesion as well as the fibrinogen adsorption on the surface were measured. The blood compatibility of Ti oxide can be improved by the addition of nitrogen into the layer. The Thrombocyte Adhesion and fibrinogen adsorption were lower for TiNxOy than for TiO2. This correlates with a lower hydrophobicity and higher polar component of the surface energy for TiNxOy. The best hemocompatibility as well as the maximal microhardness have been found for the coating TiN0.4O1.6.
-
correlation between blood compatibility and physical surface properties of titanium based coatings
Surface & Coatings Technology, 2005Co-Authors: I Tsyganov, Manfred F Maitz, E Wieser, E Richter, H ReutherAbstract:Abstract Layers of Ti nitride, Ti oxynitrides TiN x O y and Ti oxide were produced by means of metal plasma immersion ion implantation and deposition (MePIIID) from a plasma produced by cathodic arc evaporation of Ti under addition of nitrogen and/or oxygen to the ambient near the substrate. The phase composition and structure of the layers are strongly dependent on the relation of the gases partial pressure. To study the correlation between blood compatibility and physical properties of the coating the Thrombocyte Adhesion and fibrinogen adsorption on the surface as well as wettability and surface energy were investigated. Thrombocyte Adhesion and fibrinogen adsorption are lower for TiN x O y than for TiO 2 . This correlates with a lower hydrophobicity and higher polar component of the surface energy for TiN x O y .