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- Engberg, Anna E., et al.
(författare)
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Blood protein-polymer adsorption : Implications for understanding complement-mediated hemoincompatibility
- 2011
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Ingår i: Journal of Biomedical Materials Research - Part A. - : Wiley. - 1549-3296. ; 97A:1, s. 74-84
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to create polymeric materials with known properties to study the preconditions for complement activation. Initially, 22 polymers were screened for complement activating capacity. Based on these results, six polymers (P1-P6) were characterized regarding physico-chemical parameters, for example, composition, surface area, pore size, and protein adsorption from human EDTA-plasma. P2, P4, and reference particles of polystyrene and polyvinyl chloride, were hydrophobic, bound low levels of protein and were poor complement activators. Their accessible surface was limited to protein adsorption in that they had pore diameters smaller than most plasma proteins. P1 and P3 were negatively charged and adsorbed IgG and C1q. A 10-fold difference in complement activation was attributed to the fact that P3 but not P1 bound high amounts of C1-inhibitor. The hydrophobic P5 and P6 were low complement activators. They selectively bound apolipoproteins AI and AIV (and vitronectin), which probably limited the binding of complement activators to the surface. We demonstrate the usefulness of the modus operandi to use a high-throughput procedure to synthesize a great number of novel substances, assay their physico-chemical properties with the aim to study the relationship between the initial protein coat on a surface and subsequent biological events. Data obtained from the six polymers characterized here, suggest that a complement-resistant surface should be hydrophobic, uncharged, and have a small available surface, accomplished by nanostructured topography. Additional attenuation of complement can be achieved by selective enrichment of inert proteins and inhibitors.
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- Engberg, Anna E., 1982-, et al.
(författare)
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EVALUATION OF THE HEMOCOMPATIBILITY OF NOVEL POLYMERIC MATERIALS
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- When a biomaterial surface comes in contact with blood an immediate adsorption of plasma proteins to the surface will occur, and the cascade systems in the blood, such as the complement, coagulation and contact system, will be activated to various degrees. The intensity of this reaction will determine the hemocompatibility of the materials. Here we present an evaluation of the link between the composition, the physico-chemical properties and the protein adsorption properties of six newly synthesized polymers (P1-P6) and the hemocompatibility.The hemocompatibility of the polymeric surfaces was evaluated in human blood plasma and whole blood. Commercially available polyvinylchloride (PVC) was used as reference material. The hemocompatibility of the polymeric surfaces was evaluated with regard to complement activation (C3a and sC5-9 generation) and coagulation activation (platelet loss and TAT-formation) and cytokine productions (27 analytes in multiplex assay) after contact with whole blood. Contact activation was quantified by analyses of FXIIa-C1INH, FXIa-C1INH, and kallikrein-C1INH complexes.Polymers P2 (p<0.05 for C3a), P3, P5 and P6 showed less complement activation, and polymers P1 and P4 (p<0.05 for platelet loss), as well as P5 and P6 showed less coagulation activation compared with reference PVC. Polymers P1-P3 induced activation of the contact system, P3 being the most potent. Secretion of 17 cytokines including chemokines and growth factors were differentially influenced by the polymers, P1 and P3 being significantly (p<0.05) more compatible for five of the analytes.Collectively these data demonstrate that the composition of the polymers clearly leads to different biological properties as a consequence of distinctive physico-chemical properties and protein adsorption patterns.1
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- Engberg, Anna E., et al.
(författare)
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Prediction of inflammatory responses induced by biomaterials in contact with human blood using protein fingerprint from plasma
- 2015
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Ingår i: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 36, s. 55-65
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Tidskriftsartikel (refereegranskat)abstract
- Inappropriate complement activation is often responsible for incompatibility reactions that occur when biomaterials are used. Complement activation is therefore a criterion included in legislation regarding biomaterials testing. However, no consensus is yet available regarding appropriate complement-activation-related test parameters. We examined protein adsorption in plasma and complement activation/cytokine release in whole blood incubated with well-characterized polymers. Strong correlations were found between the ratio of C4 to its inhibitor C4BP and generation of 10 (mainly pro-inflammatory) cytokines, including IL-17, IFN-gamma, and IL-6. The levels of complement activation products correlated weakly (C3a) or not at all (C5a, sC5b-9), confirming their poor predictive values. We have demonstrated a direct correlation between downstream biological effects and the proteins initially adhering to an artificial surface after contact with blood. Consequently, we propose the C4/C4BP ratio as a robust, predictor of biocompatibility with superior specificity and sensitivity over the current gold standard. (C) 2014 Elsevier Ltd. All rights reserved.
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- Nilsson Ekdahl, Kristina, et al.
(författare)
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Blood protein-polymer adsorption fingerprinting: Implications for understanding hemoocompatibility and for biomaterial design.
- 2011
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Ingår i: Journal of Biomedical Materials Research. Part A. - : Wiley. - 1549-3296 .- 1552-4965. ; 97A:1, s. 74-84
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to create polymeric materials with known properties to study the preconditions for complement activation. Initially, 22 polymers were screened for complement activating capacity. Based on these results, six polymers (P1-P6) were characterized regarding physico-chemical parameters, for example, composition, surface area, pore size, and protein adsorption from human EDTA-plasma. P2, P4, and reference particles of polystyrene and polyvinyl chloride, were hydrophobic, bound low levels of protein and were poor complement activators. Their accessible surface was limited to protein adsorption in that they had pore diameters smaller than most plasma proteins. P1 and P3 were negatively charged and adsorbed IgG and C1q. A 10-fold difference in complement activation was attributed to the fact that P3 but not P1 bound high amounts of C1-inhibitor. The hydrophobic P5 and P6 were low complement activators. They selectively bound apolipoproteins Al and AIV (and vitronectin), which probably limited the binding of complement activators to the surface. We demonstrate the usefulness of the modus operandi to use a high-throughput procedure to synthesize a great number of novel substances, assay their physico-chemical properties with the aim to study the relationship between the initial protein coat on a surface and subsequent biological events. Data obtained from the six polymers characterized here, suggest that a complement-resistant surface should be hydrophobic, uncharged, and have a small available surface, accomplished by nanostructured topography. Additional attenuation of complement can be achieved by selective enrichment of inert proteins and inhibitors.
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- Rosengren-Holmberg, Jenny P., et al.
(författare)
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Heparin molecularly imprinted surfaces for the attenuation of complement activation in blood
- 2015
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Ingår i: Biomaterials Science. - : Royal Society of Chemistry (RSC). - 2047-4830 .- 2047-4849. ; 3:8, s. 1208-1217
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Tidskriftsartikel (refereegranskat)abstract
- Heparin-imprinted synthetic polymer surfaces with the ability to attenuate activation of both the complement and the coagulation system in whole blood were successfully produced. Imprinting was achieved using a template coated with heparin, a highly sulfated glycosaminoglycan known for its anticoagulant properties. The N,N'-diacryloylpiperazine-methacrylic acid copolymers were characterized using goniometry, AFM and XPS. The influence of the molecular imprinting process on morphology and template rebinding was demonstrated by radioligand binding assays. Surface hemocompatibility was evaluated using human whole blood without anticoagulants followed by measurement of complement activation markers C3a and sC5b-9 and platelet consumption as a surrogate coagulation activation marker. The observed low thrombogenicity of this copolymer combined with the attenuation of complement activation induced by the molecular imprint offer potential for the development of self-regulating surfaces with important potential clinical applications. We propose a mechanism for the observed phenomena based upon the recruitment of endogenous sulfated glycosaminoglycans with heparin-like activities.
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- Rosengren-Holmberg, Jenny P., et al.
(författare)
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Synthesis and ligand recognition of paracetamol selective polymers: semi-covalent versus non-covalent molecular imprinting.
- 2009
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Ingår i: Organic and biomolecular chemistry. - : Royal Society of Chemistry (RSC). - 1477-0520 .- 1477-0539. ; 7, s. 3148-3155
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Tidskriftsartikel (refereegranskat)abstract
- Three molecular imprinting strategies, each based upon a series of ethylene glycol dimethacrylate (EGDMA) cross-linked co-polymers, have been used to produce materials selective for the commonly used analgesic and antipyretic agent paracetamol (p-acetaminophen or 4-acetamidophenol) (1). The polymers were synthesised using either a semi-covalent imprinting strategy based upon 4-acetamidophenyl-(4-vinylphenyl) carbonate (4) or a non-covalent strategy based on methacrylic acid (MAA) as the functional monomer, or by employing a combination of these strategies. Radioligand binding studies demonstrated low template affinity in polymers offering only a single electrostatic interaction point for recognition via the phenolic residue in the template, whereas binding was substantially increased upon the introduction of a second binding mode, namely interaction at the acetamide moiety. HPLC analyses revealed no imprinting effect in the purely semi-covalent system, and only a minor effect in the purely non-covalent systems. However, a pronounced imprinting effect was demonstrated for polymers prepared by a combination of semi-covalent and non-covalent imprinting. This study illustrates a limitation of both the non-covalent and the semi-covalent strategies when it comes to achieving imprinted selectivity for small and poorly functionalised templates such as paracetamol. Parallels with conclusions from studies with antibodies are discussed.
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- Sundberg, Mark, et al.
(författare)
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Selective spatial localization of actomyosin motor function by chemical surface patterning
- 2006
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 22:17, s. 7302-7312
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Tidskriftsartikel (refereegranskat)abstract
- We have previously described the efficient guidance and unidirectional sliding of actin filaments along nanosized tracks with adsorbed heavy meromyosin (HMM; myosin II motor fragment). In those experiments, the tracks were functionalized with trimethylchlorosilane (TMCS) by chemical vapor deposition (CVD) and surrounded by hydrophilic areas. Here we first show, using in vitro motility assays on nonpatterned and micropatterned surfaces, that the quality of HMM function on CVD-TMCS is equivalent to that on standard nitrocellulose substrates. We further examine the influences of physical properties of different surfaces (glass, SiO2, and TMCS) and chemical properties of the buffer solution on motility. With the presence of methylcellulose in the assay solution, there was HMM-induced actin filament sliding on both glass/SiO2 and on TMCS, but the velocity was higher on TMCS. This difference in velocity increased with decreasing contact angles of the glass and SiO2 surfaces in the range of 20-67 degrees (advancing contact angles for water droplets). The corresponding contact angle of CVD-TMCS was 81 degrees. In the absence of methylcellulose, there was high-quality motility on TMCS but no motility on glass/SiO2. This observation was independent of the contact angle of the glass/SiO2 surfaces and of HMM incubation concentrations (30-150 mu g mL(-1)) and ionic strengths of the assay solution (20-50 mM). Complete motility selectivity between TMCS and SiO2 was observed for both nonpatterned and for micro- and nanopatterned surfaces. Spectrophotometric analysis of HMM depletion during incubation, K/EDTA ATPase measurements, and total internal reflection fluorescence spectroscopy of HMM binding showed only minor differences in HMM surface densities between TMCS and SiO2/glass. Thus, the motility contrast between the two surface chemistries seems to be attributable to different modes of HMM binding with the hindrance of actin binding on SiO2/glass.
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