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- Andersson, Marcus, 1975, et al.
(författare)
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Effect of molecular mobility of polymeric implants on soft tissue reactions: An in vivo study in rats
- 2008
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Ingår i: Journal of Biomedical Materials Research Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 84A:3, s. 652-660
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Tidskriftsartikel (refereegranskat)abstract
- Although numerous different polymers are used as implants or otherwise studied for many other biotechnical applications, there is a lack of basic models that correlate polymer characteristics with foreign body reactions. This study aims at developing one such model by systematically studying surface molecular mobility of polymeric implants in soft tissues in vivo. Changing the length of the alkyl side chain of poly(alkyl methacrylates) (PAMAs), provides an interesting opportunity to study the surface molecular mobility with minimal changes of the hydrophobicity of the surface. Thus, in this study three different PAMAs, with increasingly surface mobility; poly (isobutyl methacrylate) (PIBMA), poly(butyl methacrylate) (PBMA), and poly(lauryl methacralate) (PLMA) along with pure titanium (Ti) substrates were implanted in the dorsum of Sprague-Dawley rats. Inflammatory cell recruitment, cell adhesion, and cytokine release were studied after 1, 3, and 28 days of implantation. Total number of inflammatory cells in the exudate was measured but no correlation between surface mobility and cell recruitment where found. However, the number of surface associated cells where significantly lower on the surfaces with high molecular mobility (PLMA and PBMA). The histological evaluation performed after 28 days revealed thicker fibrous capsule and a higher number of blood vessels on the low molecular mobility surface (PIBMA). After 28 days the cell activity was higher on the high molecular mobility surfaces (PLMA and PBMA) compared with PIBMA, based on the cytokine release. None of the surfaces induced any significant cell-death. On the basis of the results of this study we conclude that there is a significant difference in biological response to surfaces with different in molecular mobility. This might affect the wound healing process and the biocompatibility of biomaterials. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007 -------------------------------------------------------------------------------- Received: 13 March 2006; Revised: 15 December 2006; Accepted: 29 January 2007 Digital Object Identifier (DOI) 10.1002/jbm.a.31389 About DOI
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| 4. |
- Andersson, Marcus, 1975, et al.
(författare)
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Quartz crystal microbalance-with dissipation monitoring (QCM-D) for real time measurements of blood coagulation density and immune complement activation on artificial surfaces
- 2005
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Ingår i: Biosensors & Bioelectronics. - : Elsevier BV. - 0956-5663. ; 21:1, s. 79-86
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Tidskriftsartikel (refereegranskat)abstract
- A recently developed variant of quartz crystal microbalance (QCM) called QCM-with dissipation monitoring (QCM-D) allows simultaneous and simple measurements of changes in adsorbed mass as well as the viscoelastic property (D-factor) of deposited protein layers on the sensor surface. We have taken the QCM-D technology a step further and demonstrated its advantages in the study of protein assembly as a consequence of surface induced immune complement activation, or contact activated blood coagulation. In the present study we have continued our QCM-D investigations of surface assembly of fibrin clot formation and complement activation and incubated differently modified quartz sensor surfaces in blood plasma and sera. Polymer surfaces used were spin-coated polyethylene, poly(ethylene terephtalate), poly(methylmetacrylate) and poly(dimethylsiloxane). Also used were sputtered titanium and heparin grafted surfaces. In this investigation we found that we could describe the surface induced coagulation with four independent parameters: (1) Time of onset of coagulation, (2) fibrin deposition rate, (3) total frequency shift at stable plateau, and (4) fibrin clot density. The most important finding was that the blood plasma clot density can be assessed with the use of D determinations and that the clot density varied significantly with the chemical composition of the surface. However, the D-factor did not give any new analytical information about the possible complement activation mechanisms. Nevertheless, the QCM-D was found to be a reliable tool for the analysis of surface induced complement activation. We also compared the QCM-D technique with traditional enzyme immuno assay (EIA) measurements of soluble products from the surface activation of the complement and coagulation systems. We found that the results from EIA and QCM-D measurements corresponded well for the complement activation but not for the coagulation, probably due to the biological complexity of the coagulation system.
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| 6. |
- Ausili, A., et al.
(författare)
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Membrane docking mode of the C2 domain of PKCε: An infrared spectroscopy and FRET study
- 2013
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - : Elsevier BV. - 0005-2736. ; 1828:2, s. 552-560
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Tidskriftsartikel (refereegranskat)abstract
- The C2 domain of PKCε binds to negatively charged phospholipids but little is known so far about the docking orientation of this domain when it is bound. By using a FRET assay we have studied the binding of this domain to model membranes. We have also used ATR-Fourier transform infrared spectroscopy with polarized light (ATR-FTIR) to determine the docking mode by calculating the β-sandwich orientation when the domain is bound to different types of model membranes. The vesicle lipid compositions were: POPC/POPE/POPA (22:36:42) imitating the inner leaflet of a plasma membrane, POPC/POPA (50:50) in which POPE has been eliminated with respect to the former composition and POPC/POPE/CL (43:36:21) imitating the inner mitochondrial membrane. Results show that the β-sandwich of the PKCα-C2 domain is inclined at an angle α close to 45 to the membrane normal. Some differences were found with respect to the extent of binding as a function of phospholipid composition and small changes on secondary structure were only evident when the domain was bound to model membranes of POPC/POPA: in this case, the percentage of β-sheet of the C2 domain increases if compared with the secondary structure of the domain in the absence of vesicles. With respect to the β-sandwich orientation, when the domain is bound to POPC/POPE/CL membranes it forms an angle with the normal to the surface of the lipid bilayer (39) smaller than that one observed when the domain interacts with vesicles of POPC/POPA (49). © 2012 Elsevier B.V. All rights reserved.
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| 7. |
- Ausili, A., et al.
(författare)
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Quartz crystal microbalance with dissipation monitoring and the real-time study of biological systems and macromolecules at interfaces
- 2012
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Ingår i: Biomedical Spectroscopy and Imaging. - 2212-8794 .- 2212-8808. ; 1:4, s. 325-338
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Tidskriftsartikel (refereegranskat)abstract
- QCM-D technique is based on the physical phenomenon that generates an acoustic shear wave with an oscillating resonance in quartz resulting in an evanescent wave that arises at the interface of the quartz and the solution. The amplitude of the acoustic wave is influenced by the deposition of material onto the quartz surface and from the subsequent decrease of the frequency the bound mass can be calculated. The dissipation shift which arises inform about viscoelasticity and flexibility of the adsorbed material. QCM-D can be applied for real-time studies of several biological systems since it is a simple, fast, low-cost and sensitive technique without having to label any sample. Common applications in biological field include measurements on adsorption of lipids, proteins, DNA and cells directly onto the surface of the sensor, which generally are chemically modified by self-assembled monolayer (SAM) technique or by spin-coated polymers. QCM-D can also be used to study molecular interactions between macromolecules and adsorbed materials. Three examples of the use of this technique are presented, namely the docking orientation of the C2 domain of PKCε on phospholipid membranes, the conformational changes of fibrinogen adsorbed to model acrylic polymers and the attachment of endothelial cells to carboxylated polymers of different configuration.
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| 8. |
- Berglin, Mattias, 1970
(författare)
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Barnacle Bioadhesive Bonding Formation, Strength and Control
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The current technology for keeping ship hulls free of marine biofouling requires the use of toxic compounds such as copper, organic biocides and tributyl tin (TBT). The compounds that are released have been shown to have negative effects on non-target organisms, and a worldwide ban of TBT is currently being introduced. An environmentally attractive alternative would be to reduce the strength of the bioadhesive bonds formed by the marine organisms. Thus, fouling organisms may be removed by grazing fish and crabs, by their own weight or by forces that are present when ships move through the water. There has been considerable interest in such systems, usually termed non-stick surfaces or fouling release coatings, for biofouling control and coatings made from poly(dimethylsiloxane) (PDMS) have shown good performance. Nevertheless, the bioadhesion still needs to be reduced for the concept to satisfy the requirements for successful biofouling control. Accomplishing that objective requires a fundamental understanding of the adhesive mechanisms and the mechanisms that control release from surfaces. The work presented in this interdisciplinary thesis has focused on the formation, the strength and the possible control of bioadhesive bonds with an emphasis on the Balanus improvisus barnacle, which is the main macrofouler found on ship hulls in Swedish waters. The major components of the bioadhesive usually termed cement were found to be three polypeptides with molecular masses of 42, 57 and 94 kD, respectively. The granular sub-micron morphology of the cement indicated a complex between the polypeptides. Incorporation of CaCO3 in the form of calcite was detected. The incorporation of CaCO3 seems to increase the cohesive strength of the adhesive plaque together with the adhesive strength. Moreover, the substrate properties were found to affect the morphology and chemistry of the adhesive plaque, and it is important to consider this barnacle response in future coating design. The barnacle bioadhesion strength was found to be affected not only by surface chemistry of the coating but also on the modulus of the coating and with decreased modulus release was facilitated. Furthermore, the surface chemistry of a condensation cured PDMS network was tailored by the incorporation of a fluorinated cross-linker. The reduced surface energy of the fluorinated coating had no significant effect on barnacle bioadhesion bond strength compared to a non-fluorinated control. However, the morphological and chemical stability of the coating surface was greatly improved, which resulted in significantly lower barnacle bioadhesion bond strength measured on the fluorinated coating compared to the non-fluorinated control after prolonged exposure to seawater. The results presented in this thesis demonstrate the importance to understand and characterize the biointerface between the adhesive plaque produced by the barnacle and the synthetic polymer. With this knowledge we now have a new platform for developing innovative fouling-release coatings.
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| 10. |
- Berglin, Mattias, 1970, et al.
(författare)
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Erosion of a model rosin-based marine antifouling paint binder as studied with quartz crystal microbalance with dissipation monitoring (QCM-D) and ellipsometry
- 2008
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Ingår i: Progress in Organic Coatings. ; 61, s. 83-88
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Tidskriftsartikel (refereegranskat)abstract
- In this study two surface sensitive methods, i.e. quartz crystal microbalance with dissipation monitoring (QCM-D) and ellipsometry, were used for erosion measurements of a rosin-based marine antifouling paint binder. Thin films of the binder were applied on sensor surfaces by the means of spin-coating and the effect of water velocity over the paint film, water temperature or ionic strength on erosion was investigated. Both the acoustic QCM-D model and the optical ellipsometry model gave comparable erosion results. The initial 2-50 nm rapid erosion of the top layer was followed by steady-state erosion rate until end of experiment. For example, the steady-state erosion rate was 12 nm/24 h in artificial seawater at 23 degrees C and with a flow of 200 mu l/min over the paint surface as measured with QCM-D. The erosion rate increased with increased velocity and increased temperature. Ionic strength had no effect on the erosion rate of this model binder. At low water velocities the surface layer was highly dissipative indicating a water filled surface top layer or the formation of deposits on the surface. New characterization techniques that are able to study the erosion mechanisms on the nanometre scale are sought for as the binders get more technically complex containing, for example, nanoparticles or enzymes. Surface sensitive methods could be used to rapidly screen the effect of different binder chemistries or paint additives on the erosion during the paint development process. (C) 2007 Elsevier B.V. All rights reserved.
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