Hans Jörg Mathieu · Materials Department, Swiss Federal Institute of Technology Lausanne (EPFL). CH-1015 Lausanne EPFL, Switzerland. INTRODUCTION:.
European Cells and Materials Vol. 1. Suppl. 2, 2001 (page 17)
ISSN 1473-2262
TOWARDS CONTROL OF CELL-BIOMATERIAL INTERACTION: STEP BY STEP CHARACTERIZATION OF THE SURFACE CHEMISTRY WITH XPS AND IMAGING TOF-SIMS Hans Jörg Mathieu Materials Department, Swiss Federal Institute of Technology Lausanne (EPFL) CH-1015 Lausanne EPFL, Switzerland INTRODUCTION: Newly developed functionalised surfaces aim to mimic biological systems to obtain defined and controlled interactions with biomolecules or living cells. Cell plasma membranes display arrays of receptors that interact with specific ligands of viral or bacterial origin. Carbohydrate-protein interactions, surface chemistry and surface wettability play key roles in a number of recognition cell processes. The surface determines essentially the biocompatibility, whereas the bulk decides the physical, mechanical and rheological properties required for an implant. Various classes of materials used as biomaterials (metals like Titanium), polymers (poly-urethanes, polytetrafluoroethylene, PVC, …) and coatings (diamond-like-carbon) are applied in sensing, dental, orthopaedic or cardiovascular devices. METHODS: This review recalls the principles of major surface characterization methods with nm depth resolution. Wetting of a surface controlled by contact angle measurements allows to distinguish hydrophilic from hydrophobic surfaces within the sub-nano region. The micro-chemical surface characterization by X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is discussed. Both techniques, performed ex-situ under Ultra-High Vacuum (UHV) conditions allow determination of the surface chemistry with high sensitivity down to the femto-mol level. RESULTS: Practical results from different fields are presented: (1) hydrocarbon adsorption on biochip sensing devices (Fig.1), (2) plasma modification of polymers (PVC) to reduce bacteria colonization 2, and (3) biodegradation of titanium after long time implantation 3. CONCLUSIONS: • the surface chemistry and topography can be analytically controlled • sub-micron imaging of functional biochemical groups is possible
• nanometer resolution coupled with high surface sensitivity can be reached
Fig. 1 ToF-SIMS CN- image of a microcontact printed pattern (µCP) of peptide PA22-2 on sulfoGMBS modified wafer for neuronal network 1 REFERENCES: 1
D. Léonard, M. Scholl, Y. Chevolot, C. Sprössler, M.C. Denyer, A. Offenhäusser, W. Knoll, A. Maelicke, H. Sigrist and H.J. Mathieu (2000) Surface Chemistry and Microcontact Printed Patterns for Neuronal Network Architectures Studied by Tof-SIMS, Proc. SIMS XII Brussels, (eds. A. Benninghoven, P. Bertrand, H.-N. Migeon, H. W. Werner), Brussels, Elsevier, Amsterdam, pp 939-942.
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D. Balacz, D. Favez, Y. Chevolot, N. Xanthopoulos , C. Granges, B.-O. Aronsson, F. Sidouni, P. Descouts and H.J. Mathieu (2001) Surface Modification of PVC Endotracheal Tubes: Oxygen Plasma Treatment and Aging Effects, in preparation
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L. Jonas, G. Fulda, C. Radeck, K.-O. Henkel, G. Holzhüter and H.J. Mathieu (2001) Biodegradation of Metallic Titanium Implants After Long Time Insertion. Element Analysis by Electron Microscopy and EDX or EELS. subm. to Ultrastructural Pathology ACKNOWLEDGEMENTS: This work is partially financed by the Common Research Programme on Biomedical Engineering 99-02, HUG – UNIL - EPFL – Uni Genève – CHUV.
