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Protein adsorption on thin films of carbon and carbon nitride monitored with in situ ellipsometry
Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.
Department of Biomaterials, Institute of Surgical Sciences, The Sahlgrenska Academy, University of Gothenburg.
Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, The Institute of Technology.ORCID iD: 0000-0001-9229-2028
2011 (English)In: ACTA BIOMATERIALIA, ISSN 1742-7061, Vol. 7, no 3, 1369-1378 p.Article in journal (Refereed) Published
Abstract [en]

Amorphous carbon and amorphous, graphitic and fullerene-like carbon nitride thin filmswere deposited by reactive magnetron sputtering and optically characterized withspectroscopic ellipsometry. The films were exposed to human serum albumin and theadsorption was monitored in situ using dynamic ellipsometry. From the ellipsometric data theadsorbed amount of proteins was quantified in terms of surface mass density using de Feijter'smodel. The results indicated larger adsorption of proteins onto the amorphous films comparedto the films with a more ordered microstructure. Complementary studies with labeled HSAusing radioimmunoassay showed up to 6 times higher protein adsorption compared to theellipsometry measurement which partly might be explained by differences in surfaceroughness (from 0.3 to 13 nm) among the films. The elutability of adsorbed labeled HSAusing unlabeled HSA and sodium dodecyl sulphate was low compared to a silicon reference.In addition, the four types of films were incubated in blood plasma followed by antifibrinogen,anti-HMWK or anti-C3c revealing the materials response to complement andcontact activation. Three of the films indicated immunoactivity, whereas the amorphouscarbon showed less immunoactivity compared to a titanium reference. All films showedindications of a stronger ability to initiate the intrinsic pathway of coagulation, compared tothe reference. Finally, the surfaces bone bonding ability was investigated by examination oftheir ability to form calcium phosphate (CaP) crystals in a simulated body fluid, with a-CNxdepositing most CaP after 21 days of incubation.

Place, publisher, year, edition, pages
Elsevier Science B.V. Amsterdam , 2011. Vol. 7, no 3, 1369-1378 p.
National Category
Natural Sciences
URN: urn:nbn:se:liu:diva-19706DOI: 10.1016/j.actbio.2010.10.024ISI: 000287643900049OAI: diva2:227664
Original Publication: Torun Berlind, Pentti Tengvall, Lars Hultman and Hans Arwin, Protein adsorption on thin films of carbon and carbon nitride monitored with in situ ellipsometry, 2011, ACTA BIOMATERIALIA, (7), 3, 1369-1378. Copyright: Elsevier Science B.V. Amsterdam Available from: 2009-07-16 Created: 2009-07-16 Last updated: 2013-10-14Bibliographically approved
In thesis
1. Carbon Nitride: Characterization and Protein Interactions
Open this publication in new window or tab >>Carbon Nitride: Characterization and Protein Interactions
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis concerns synthesis and characterization of carbon-based materials and theinvestigation of the possible use, of a selection of these materials, in biomedicalapplications. Protein adsorption and blood plasma tests were used for this purposeutilizing a surface sensitive technique called spectroscopic ellipsometry.

The materials were synthesized by physical vapor deposition and characterizedregarding microstructure, mechanical properties and optical properties. The ternaries BC-N and Si-C-N as well as carbon and carbon nitrides (CNx) of different microstructureshave been examined. In the B-C-N work, the intention was to investigate the possibilityto combine the two materials CNx and BN, interesting on their own regarding highhardness and extreme elasticity, to produce a material with even better properties.Theoretical calculations were performed to elucidate the different element substitutionsand defect arrangements in the basal planes promoting curvature in the fullerene-likemicrostructure. The Si-C-N ternary was investigated with the consideration of finding away to control the surface energy for certain applications. Amorphous carbon and threemicrostructures of CNx were analyzed by spectroscopic ellipsometry in the UV-VIS-NIRand IR spectral ranges in order to get further insight into the bonding structure of thematerial.

In the second part of this work focus was held on studies of macromolecularinteractions on silicon, carbon and CNx film surfaces using ellipsometry. One purposewas to find relevance (or not) for these materials in biological environments. Materials for bone replacement used today, e.g. stainless steel, cobalt-chromium alloys andtitanium alloys suffer from corrosion in body fluids, generation of wear particles inarticulating systems, infections and blood coagulation and cellular damage leading toimpaired functionality and ultimately to implant failure. Artificial heart valves made ofpyrolytic carbon are used today, with friction and wear problems. Thus, there is still aneed to improve biomaterials. The aim of the fourth paper was to investigate theinteraction between carbon-based materials and proteins. Therefore, amorphous carbon(a-C), amorphous (a), graphitic (g) and fullerene-like (FL) CNx thin films were exposedto human serum albumin and blood plasma and the amount of protein was measured insitu using spectroscopic ellipsometry. Surface located and accessible proteins after blood plasma incubations were eventually identified through incubations in antibody solutions.

Antibody exposures gave indications of surface response to blood coagulation,complement activation and clotting. The a-C and FL-CNx films might according to theresults have a future in soft tissue applications due to the low immuno-activity, whereasthe g-CNx film possibly might be a candidate for bone replacement applications.

"Layered" structures of fibrinogen, a fibrous but soft protein involved in manyprocesses in our body, were grown in situ and dynamically monitored by ellipsometry inorder to understand the adsorption process and molecule arrangement onto a siliconsurface.

In the last paper of this thesis, the effects of ion concentration and proteinconcentration on the refractive index of water-based solutions used in in situ ellipsometrymeasurements were demonstrated and spectral refractive index data for water solutionswith different ionic strengths and protein concentrations have been provided.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2009. 67 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1263
National Category
Natural Sciences
urn:nbn:se:liu:diva-19710 (URN)978-91-7393-593-7 (ISBN)
Public defence
2009-08-28, Planck, Fysikhuset, Campus Valla, Linköpings universitet, Linköping, 10:15 (English)
Available from: 2009-07-16 Created: 2009-07-16 Last updated: 2013-10-14Bibliographically approved

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