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Adsorption behavior of human plasma fibronectin on hydrophobic and hydrophilic Ti6Al4V substrata and its influence on bacterial adhesion and detachment.

Vadillo-Rodríguez V, Pacha-Olivenza MA, Gónzalez-Martín ML, Bruque JM, Gallardo-Moreno AM.

J Biomed Mater Res A. 2013 May;101(5):1397-404.

Department of Applied Physics, Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), University of Extremadura, Badajoz, Spain. [email protected]

 

Abstract

 

Due to its excellent material properties, including high resistance to corrosion, high mechanical strength and good biocompatibility, Ti6Al4V is one of the most clinically used biomaterials. However, the host response to Ti6Al4V is not always favorable and bacterial adhesion to an initially adsorbed protein layer on the biomaterial/tissue interface often lead to implant failure. In this study, the influence of protein surface orientation on bacterial adhesion has been examined using three clinically relevant bacterial strains known to express specific binding sites for human plasma fibronectin (HFN), a protein that has been suggested to play a major role in the interaction of implant materials with the surrounding matrices. HFN was allowed to adsorb onto hydrophobic and physically modified hydrophilic Ti6Al4V surfaces and the results show that the conformation of the adsorbed molecules mainly depends on solid surface tension and the initial protein concentration in solution. In particular, ellipsometric data reveal that the adsorbed HFN molecules adopt a more extended conformation on hydrophobic than hydrophilic surfaces, an effect that is more pronounced at low than high initial protein concentrations. The extended conformation adopted by the molecules on the hydrophobic surfaces probably facilitates the exposure of specific sites for adhesion, resulting in higher cell attachment regardless of the bacterial strain examined. Contact angle measurements further suggest that non-specific (hydrophobic) interactions play a significant role in adhesion, i.e. bacterial adhesion increases with surface hydrophobicity in the absence or presence of the adsorbed HFN surface layers. Moreover, the analysis of the number of remaining adhering cells after being subjected to an external force indicates that specific interactions also contribute to strengthen the bond between the cells and the protein-coated material surfaces. Importantly, this study is the first one to evaluate the influence of surface hydrophobicity on protein adsorption and its subsequent effect on bacterial adhesion using a material whose hydrophobicity was not modified using the typically employed surface modification treatments, which likely lead to morphological and chemical as well as hydrophobicity surface changes.

 

 

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REPEAT Adsorption behavior of human plasma fibronectin