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  • 1.
    Arvidsson, Sara
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Askendal, Agneta
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Lindahl, Tomas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry.
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Detection of surface bound complement at increasing serum anticoagulant concentrations2008In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 62, p. 214-219Article in journal (Refereed)
    Abstract [en]

      

  • 2.
    Arvidsson, Sara
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Askendal, Agneta
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Blood plasma contact activation on silicon titanium and aluminium2007In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 28, p. 1346-1354Article in journal (Refereed)
    Abstract [en]

       

  • 3.
    Arwin, Hans
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Askendal, Agneta
    Linköping University, Department of Physics, Chemistry and Biology.
    Berlind, Torun
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Optics .
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Thompson, Dan W
    Department of electrical engineering University of Nebraska.
    Tiwald, T
    Woollam, John A.
    Department of electrical engineering University of Nebraska.
    Infrared ellipsometry studies of temperature effects on multilayers of ANTI-human serum albumin and its antigen2005In: E-MRS,2005, 2005Conference paper (Other academic)
  • 4.
    Arwin, Hans
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
    Askendal, Agneta
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Tengvall, Pentti
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Thompson, Daniel W.
    University of Nebraska, Lincoln, NE, USA.
    Woollam, John A.
    J. A. Woollam Co., Inc, Lincoln, NE, USA.
    Infrared ellipsometry studies of thermal stability of protein monolayers and multilayers2008In: Physica Status Solidi. C: Current Topics in Solid State Physics, ISSN 1862-6351, Vol. 5, no 5, p. 1438-1441Article in journal (Refereed)
    Abstract [en]

    Methodology for studies of effects of heating multilayers of human serum albumin (HSA) and anti-HSA is presented. Multilayers of anti-HSA were prepared on silicon substrates and studied with infrared spectroscopic ellipsometry equipped with a heat stage. The refractive index N = n + ik and the layer thickness are determined and the amide bands are analyzed. It is found that HSA/anti-HSA multilayers are stable for shorter times at temperatures above 100 °C, except for small thickness changes. Also pilot studies of effects of heating monolayers of proteins adsorbed on gold substrates is presented.

  • 5.
    Benesch, Johan
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Askendal, Agneta
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Quantification of adsorbed human serum albumin at solid interfaces: A comparison between radioimmunoassay (RIA) and simple null ellipsometry2000In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 18, no 2, p. 71-81Article in journal (Refereed)
    Abstract [en]

    Radioimmunoassay (RIA) and null ellipsometry are two common methods to quantify adsorbed proteins. However, the accuracy of null ellipsometry with a constant protein refractive index (n=1.465, k=0) at ?=632.8 nm has this far not been explored. The present study compared the methods, and the degree of agreement between the simplified single wavelength null ellipsometry and RIA to quantify adsorbed proteins was explored on different surfaces. The quantification methods agreed well when Angstrom smooth hydrophilic or hydrophobic silicon surfaces, and freshly radio-labelled proteins were used. Some discrepancies were noted when either rough surface or stored and aged labelled proteins were used. The differences decreased when the aged protein solution was equilibrated with freshly dissolved proteins at room temperature (RT) for a few hours prior to the surface incubations. Significant differences were also noted between the methods when albumin was adsorbed at it's iso-electric point (pH 4.8). Copyright (C) 2000 Elsevier Science B.V.

  • 6.
    Benesch, Johan
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Askendal, Agneta
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    The determination of thickness and surface mass density of mesothick immunoprecipitate layers by null ellipsometry and protein 125Iodine labeling2002In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 249, no 1, p. 84-90Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to ellipsometrically determine the thickness and surface mass density in air for up to 110-nm-thick organic layers made of alternatingly deposited layers of HSA and polyclonal anti-HSA on hydrophobic silicon. The ellipsometrically determined thickness was compared to that obtained by AFM and the deposited surface mass density calibrated with 125I-labeled proteins. The results indicate a good agreement in protein layer thickness between AFM and ellipsometry when the protein film refractive index Nfilm = 1.5 -0i, although then the calculated surface mass density from the ellipsometry data became grossly overestimated by the Cuypers one-component formula. A good agreement in the surface mass density was obtained when the M/A ratio in this formula was lowered from 4.14 to 2.35. This approach indicates a convenient means of determining the refractive indices and surface mass densities of mesothick organic layers proteins on solid supports. © 2002 Elsevier Science (USA).

  • 7.
    Ericsson, Emma
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Faxälv, Lars
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry.
    Weissenrieder, Anna
    St Paul, USA.
    Askendal, Agneta
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Tengvall, Pentti
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Glycerol monooleate-blood interactions2009In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 68, no 1, p. 20-26Article in journal (Refereed)
    Abstract [en]

    In the present study the initial blood compatibility of glycerol monooleate (GMO)-coated surfaces was evaluated after deposition to surfaces and in bulk. The model surface was silica onto which multiple layers of fibrinogen or human serum albumin (HSA) was immobilized. The protein-coated surfaces were subsequently dip-coated in GMO in ethanol and used for blood plasma and whole blood experiments. The characterization methods included null ellipsometry, scanning electron microscopy, imaging of coagulation, hemolysis test and whole blood coagulation time by free oscillation rheometry.

    The results showed a GMO film thickness of approximately 350 angstrom (similar to 4 mu g/cm(2)) upon dip-coating in ethanolic solution. A major part of the deposited layer detached in aqueous solutions, especially during shear conditions. The coagulation time on GMO was significantly prolonged compared to that on HSA coated silica. Whole blood tests showed that GMO is a very weak hemolytic agent. Deposited GMO detached easily from surfaces upon rinsing or shearing, although a stable layer with undefined phase structure and a thickness of 50-70 angstrom remained on HSA and fibrinogen precoated surfaces. This indicates that GMO has stronger adhesive forces to its substrate compared to the cohesive forces acting within the bulk GMO. The ability of GMO to detach from itself and tentatively form micelles or lipid bilayers when subjected to flowing blood may be of use in extravascular applications. It is concluded that GMO results in weak blood activation, and the material may in spite of this be suitable in selected biomaterial applications, especially as a biosealant and in colloidal dispersions.

  • 8.
    Linderbäck, Paula
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Harmankaya, Necati
    Gothenburg University.
    Askendal, Agneta
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Areva, Sami
    University of Turku.
    Lausmaa, Jukka
    SP Technical Research Institute Sweden.
    Tengvall, Pentti
    Gothenburg University.
    The effect of heat- or ultra violet ozone-treatment of titanium on complement deposition from human blood plasma2010In: BIOMATERIALS, ISSN 0142-9612, Vol. 31, no 18, p. 4795-4801Article in journal (Refereed)
    Abstract [en]

    Titanium (Ti) is a well known metallic biomaterial extensively used in dental, orthopaedic-, and occasionally also in blood contacting applications. It integrates well to bone and soft tissues, and is shown upon blood plasma contact to activate the intrinsic pathway of coagulation and bind complement factor 3b. The material properties depend largely on those of the nm-thick dense layer of TiO2 that becomes rapidly formed upon contact with air and water. The spontaneously formed amorphous Ti-oxide has a pzc similar to 5-6 and its water solubility is at the order of 1-2 micromolar. It is often subjected to chemical- and heat treatments in order to increase the anatase- and ruble crystallinity, to modify the surface topography and to decrease the water solubility. In this work, we prepared sol gel derived titanium and smooth PVD titanium surfaces, and analysed their oxide and protein deposition properties in human blood plasma before and after annealing at 100-500 degrees C or upon UVO-treatment for up to 96 hours. The blood plasma results show that complement deposition vanished irreversibly after heat treatment at 250-300 degrees C for 30 minutes or after UVO exposure for 24 hours or longer. XPS and infrared spectroscopy indicated change of surface water/hydroxyl binding upon the heat- and UVO treatments, and increased Ti oxidation. XRD analysis confirmed an increased crystallinity and both control (untreated) and annealed smooth titanium displayed low XRD-signals indicating some nanocrystallinity, with predominantly anatase phase. The current results show that the behaviour of titanium dioxide in blood contact can be controlled through relatively simple means, such as mild heating and illumination in UV-light, which both likely irreversibly change the stoichiometry and structure of the outmost layers of titanium dioxide and its OH/H2O binding characteristics.

  • 9.
    Pasternak, Björn
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Orthopaedics and Sports Medicine . Linköping University, Faculty of Health Sciences.
    Missios, Anna
    Askendal, Agneta
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Tengvall, Pentti
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Aspenberg, Per
    Linköping University, Department of Clinical and Experimental Medicine, Orthopaedics and Sports Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Orthopaedic Centre, Department of Orthopaedics Linköping.
    Doxycycline-coated sutures improve the suture-holding capacity of the rat Achilles tendon2007In: Acta Orthopaedica, ISSN 1745-3674, Vol. 78, no 5, p. 680-686Article in journal (Refereed)
    Abstract [en]

    There is evidence of high matrix metalloproteinase (MMP) activity around sutures inserted into tendons. This probably results in tissue breakdown, allowing the suture to cut through the tendon, and thus contributes to repair-site elongation and gap formation. We therefore hypothesized that treatment with the MMP inhibitor doxycycline would improve the sutureholding capacity of tendon. Animals, methods and results In the first sub-study, rats received a suture in the Achilles tendon. One group was treated with systemic doxycycline and the other received no treatment. At 3, 5, and 7 days, suture-holding capacity was measured mechanically. The pull-out force and energy were reduced in all tendons, at 3 days compared to freshly inserted sutures, but no further reduction was detected at later time points. Doxycycline- treated tendons showed improved suture-holding capacity as measured by higher energy uptake than in untreated tendons. Force at failure showed a trend towards improvement. The effect was most evident on day 3. In the second sub-study, sutures were coated with doxycycline. At 3 days, local doxycycline treatment caused improved suture-holding capacity—as measured by higher force at failure and higher energy uptake.

  • 10.
    Sjöwall, Christoffer
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Rheumatology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Rheumatology in Östergötland.
    Wetterö, Jonas
    Linköping University, Department of Clinical and Experimental Medicine, Rheumatology. Linköping University, Faculty of Health Sciences.
    Bengtsson, Torbjörn
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Askendal, Agneta
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Skogh, Thomas
    Linköping University, Department of Clinical and Experimental Medicine, Rheumatology. Linköping University, The Institute of Technology. Östergötlands Läns Landsting, Centre for Medicine, Department of Rheumatology in Östergötland.
    Tengvall, Pentti
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Solid-phase classical complement activation by C-reactive protein (CRP) is inhibited by fluid-phase CRP-C1q interaction2007In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 352, no 1, p. 251-258Article in journal (Refereed)
    Abstract [en]

    C-reactive protein (CRP) interacts with phosphorylcholine (PC), Fcγ receptors, complement factor C1q and cell nuclear constituents, yet its biological roles are insufficiently understood. The aim was to characterize CRP-induced complement activation by ellipsometry. PC conjugated with keyhole limpet hemocyanin (PC-KLH) was immobilized to cross-linked fibrinogen. A low-CRP serum with different amounts of added CRP was exposed to the PC-surfaces. The total serum protein deposition was quantified and deposition of IgG, C1q, C3c, C4, factor H, and CRP detected with polyclonal antibodies. The binding of serum CRP to PC-KLH dose-dependently triggered activation of the classical pathway. Unexpectedly, the activation was efficiently down-regulated at CRP levels >150 mg/L. Using radial immunodiffusion, CRP–C1q interaction was observed in serum samples with high CRP concentrations. We propose that the underlying mechanism depends on fluid-phase interaction between C1q and CRP. This might constitute another level of complement regulation, which has implications for systemic lupus erythematosus where CRP is often low despite flare-ups.

  • 11.
    Tengvall, Pentti
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Arvidsson, Sara
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Askendal, Agneta
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Ellipsometric detection of blood plasma contact activation on model biomaterial surfaces2007In: ICSE4,2007, 2007Conference paper (Other academic)
  • 12.
    Tengvall, Pentti
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Arvidsson, Sara
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Askendal, Agneta
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Factor XII Dependent Complement Deposition from Blood Plasma onto Silicon,Ttitanium and Aluminium2007In: 21 st European Conference on Biomaterials,2007, 2007Conference paper (Other academic)
    Abstract [en]

      

  • 13.
    Tengvall, Pentti
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Askendal, Agneta
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Ellipsometric in vitro studies on blood plasma and serum adsorption to zirconium2001In: Journal of Biomedical Materials Research, ISSN 0021-9304, E-ISSN 1097-4636, Vol. 57, no 2, p. 285-290Article in journal (Refereed)
    Abstract [en]

    Ellipsometry/ antibody techniques were used to study the adsorption of heparinized human blood plasma and serum onto spontaneously oxidized zirconium, and a colorimetric assay measured the formation of kallikrein by the surface in citrated plasma. After 10 min incubation in the blood plasma the protein film thickness was approximately 4.2 nm, and the film bound polyclonal antibodies mainly against high molecular weight kininogen (HMWK), immunoglobulin G (IgG) and fibrinogen. After 5 or 60 min of incubations in whole normal or EGTA sera, antibodies against complement factor 3 (C3) and complement factor 3d (C3d) deposited to the surface. Factor H and complement factor 1q (C1q) were detected similarly after I and 5 min of incubation in 1-10% normal serum in veronal buffer, respectively. The indications are that upon contact with blood plasma, zirconium activates the intrinsic pathway of coagulation and is opsonized with C3. The failure to detect properdin and transient presence of factor H at the surface suggest that complement binds to zirconium although the activation becomes quickly down-regulated. (C) 2001 John Wiley & Sons, Inc.

  • 14.
    Tengvall, Pentti
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Askendal, Agneta
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Lundström, Ingemar
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Ellipsometric in vitro studies on the activation of complement by human immunoglobulins M and G after adsorption to methylated silicon2001In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 20, no 1, p. 51-62Article in journal (Refereed)
    Abstract [en]

    Human serum immunoglobulin M (IgM) or human immunoglobulin G (IgG) were adsorbed to dichlorodimethyl silane (DDS) treated silicon. Subsequently, the model surfaces were incubated in normal-, complement factor 1q (C1q)-complement factor B or complement factor 2 (C2)-depleted human sera at 37°C for up to 1.5 h. The serum deposition and binding of selected polyclonal complement antibodies into this layer were then quantified by null ellipsometry. Both types of precoated surfaces bound large amounts of anti-complement factor 3c (anti-C3c), anti-properdin and anti-C3d, after incubation in normal serum. In contrast to IgG coated surfaces, IgM coated surfaces bound no anti-C1q after the serum incubations and no anti-C3c deposition lag time was observed after incubations in EGTA serum. Upon immersions of IgM coated surfaces in the different sera, a rapid complement activation via a C1q factor B, and Ca2+-independent, but C2 dependent pathway, was indicated. When IgM was instead immobilized to APTES/glutaraldehyde surfaces, anti-C3c deposition was lower after incubations in EGTA than normal serum. The results suggest that, under the present experimental conditions, human IgM and IgG activate the complement system differently. (C) 2001 Elsevier Science B.V.

  • 15.
    Tengvall, Pentti
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Jansson, Eva
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Askendal, Agneta
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Thomsen, P.
    Inst. of Anatomy and Cell Biology, Göteborg University, P.O. Box 420, SE-405 30 Gotebörg, Sweden.
    Gretzer, C.
    Inst. of Anatomy and Cell Biology, Göteborg University, P.O. Box 420, SE-405 30 Gotebörg, Sweden.
    Preparation of multilayer plasma protein films on silicon by EDC/NHS coupling chemistry2003In: Colloids and Surfaces B: Biointerfaces, ISSN 0927-7765, E-ISSN 1873-4367, Vol. 28, no 4, p. 261-272Article in journal (Refereed)
    Abstract [en]

    Crosslinked multilayer protein films were prepared from fibrinogen, albumin, IgG, a combination of fibrinogen and catalase, and blood plasma on silicon by ethyl-dimethyl-aminopropylcarbodiimide and N-hydroxy-succinimide coupling chemistry. The 4-70 nm thick films were placed in blood plasma and the additional protein deposition measured by null ellipsometry after 5 or 60 min of incubation. The activation of the complement system and intrinsic pathway of coagulation were indicated through the subsequent binding of anti-C3c, anti-C3d, anti-properdin and anti-HMWK on top of the surface bound blood plasma. The proportion of Annexin V, Propidium Iodide and 4,6-diamidino-2-phenylindole positive cells, and the secretion of tumor necrosis factor a (TNF-a) and interleukin-10 (IL-10) were analysed in a monocyte culture. The results show that well known protein coupling techniques can be used for the preparation of protein layers with well controlled thickness. The layers possess low contact activation of blood plasma and induce different release of TNF-a and IL-10 in monocyte cultures. © 2002 Elsevier Science B.V. All rights reserved.

  • 16.
    Tengvall, Pentti
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics . Linköping University, The Institute of Technology.
    Skoglund, Björn
    Linköping University, Department of Clinical and Experimental Medicine, Orthopaedics and Sports Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Orthopaedic Centre, Department of Orthopaedics Linköping.
    Askendal, Agneta
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Aspenberg, Per
    Linköping University, Department of Clinical and Experimental Medicine, Orthopaedics and Sports Medicine . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Orthopaedic Centre, Department of Orthopaedics Linköping.
    Surface Immobilized Bisphosphonate Improves Stainless-Steel Screw Fixation in Rats2004In: Biomaterials, ISSN 0142-9612, Vol. 25, no 11, p. 2133-2138Article in journal (Refereed)
    Abstract [en]

    An increase in the mechanical fixation in bone of metallic biomaterials is considered advantageous in joint replacement and fracture surgery. Different approaches to improve fixation may be e.g. surface roughening, Ca-mineral coating or surface immobilization of growth factors or drugs. In the present work, bisphosphonate, a class of drugs that inhibit bone resorption, was immobilized onto stainless-steel screws.

    The screws were first roughened and coated with immobilized and cross-linked fibrinogen. Subsequently, an N-bisphosphonate, pamidronate, was immobilized onto fibrinogen, and another N-bisphosphonate, ibandronate, adsorbed on top of this. The so coated screws were inserted into the tibiae of eight male Sprague-Dawley rats. Another eight rats received screws prepared in the same way, but without the bisphosphonate coating. Pullout strength tests were performed after 2 weeks of implantation.

    The results showed a 28% (p=0.0009) higher pullout force and 90% increased pullout energy for the bisphosphonate coated screws, and support the idea that surface immobilized bisphosphonates can be used to improve biomaterials fixation in bone.

  • 17.
    Tosatti, S.
    et al.
    Lab. for Surf. Sci. and Technology, Department of Materials, Swiss Fed. Inst. Technol. (ETH) Z., CH-8092 Zurich, Switzerland.
    De, Paul S.M.
    De Paul, S.M., Lab. for Surf. Sci. and Technology, Department of Materials, Swiss Fed. Inst. Technol. (ETH) Z., CH-8092 Zurich, Switzerland, Solvias AG, Klybeckstrasse 191, CH-4002 Basel, Switzerland.
    Askendal, Agneta
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    VandeVondele, S.
    Institute for Biomedical Engineering, Department of Materials, ETH and University of Zurich, CH-8092 Zurich, Switzerland.
    Hubbell, J.A.
    Institute for Biomedical Engineering, Department of Materials, ETH and University of Zurich, CH-8092 Zurich, Switzerland.
    Tengvall, Pentti
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Applied Physics .
    Textor, M.
    Lab. for Surf. Sci. and Technology, Department of Materials, Swiss Fed. Inst. Technol. (ETH) Z., CH-8092 Zurich, Switzerland.
    Peptide functionalized poly(L-lysine)-g-poly(ethylene glycol) on titanium: Resistance to protein adsorption in full heparinized human blood plasma2003In: Biomaterials, ISSN 0142-9612, E-ISSN 1878-5905, Vol. 24, no 27, p. 4949-4958Article in journal (Refereed)
    Abstract [en]

    The graft copolymer poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) and its RGD- and RDG-functionalized derivatives (PLL-g-PEG/PEG-peptide) were assembled from aqueous solutions on titanium (oxide) surfaces. The polymers were characterized by NMR in order to determine quantitatively the grafting ratio, g (Lys monomer units/PEG side chains), and the fraction of the PEG side chains carrying the terminal peptide group. The titanium surfaces modified with the polymeric monomolecular adlayers were exposed to full heparinized blood plasma. The adsorbed masses were measured by in situ ellipsometry. The different PLL-g-PEG-coated surfaces showed, within the detection limit of the ellipsometric technique, no statistically significant protein adsorption during exposure to plasma for 30min at 22°C or 37°C, whereas clean, uncoated titanium surfaces adsorbed approximately 350ng/cm2 of plasma proteins. The high degree of resistance of the PEGylated surface to non-specific adsorption makes peptide-modified PLL-g-PEG a useful candidate for the surface modification of biomedical devices such as implants that are capable of eliciting specific interactions with integrin-type cell receptors even in the presence of full blood plasma. The results refer to short-term blood plasma exposure that cannot be extrapolated a priori to long-term clinical performance. © 2003 Elsevier Ltd. All rights reserved.

  • 18.
    Wetterö, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, The Institute of Technology.
    Askendal, Agneta
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Tengvall, Pentti
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Bengtsson, Torbjörn
    Linköping University, Department of Molecular and Clinical Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Interactions between surface-bound actin and complement, platelets, and neutrophils2003In: Journal of Biomedical Materials Research, ISSN 0021-9304, E-ISSN 1097-4636, Vol. 66A, no 1, p. 162-175Article in journal (Refereed)
    Abstract [en]

    Actin exists as globular (G) monomers or polymeric filaments (F) in the cytoplasm of eukaryotic cells, mediating cell morphologic changes and motility. Large amounts of this protein may be released out to the extracellular compartment during tissue injury, but little is known about its role in biomaterial-related inflammation. We immobilized actin to methylated glass, methylated and aminated silicon, and gold model surfaces and studied the subsequent blood serum deposition and complement activation, generation of reactive oxygen species (ROS), and adhesion and aggregation of neutrophils and platelets. Null ellipsometry showed that approximately one monolayer of G-actin can be immobilized onto the model surfaces and that actin in buffer polymerized on top of this by the addition of K+ and Mg2+ ions to form a thicker layer of firmly bound F-actin. After serum incubation, F-actin bound low amounts of anti-complement factor 1q (anti-C1q). Cell responses upon contact with actin-coated surfaces were analyzed by luminol-amplified chemiluminescence, lumi-aggregometry, and fluorescence microscopy. It was shown that surface-triggered aggregation, spreading, and generation of ROS are down-regulated and comparable to the response by adsorbed albumin. However, F-actin on gold surfaces recruited platelets in a C1q-dependent manner. We conclude that in vitro adsorbed actin is a weak complement, platelet, and neutrophil activator, but that F-actin associates with both C1q and platelets. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 66A: 162–175, 2003

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