Protein resistance of surfaces prepared by sorption of end-thiolated poly(ethylene glycol) to gold: effect of surface chain density

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DOIResolve DOI: http://doi.org/10.1021/la047672dS0743-7463(04)07672-3
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TypeArticle
Journal titleLangmuir
ISSN0743-7463
Volume21
Issue3
Pages10361041; # of pages: 6
AbstractNonspecific protein adsorption generally occurs at the biomaterial-tissue interface and usually has adverse consequences. Thus, surfaces that are protein-resistant are eagerly sought with the expectation that these materials will exhibit improved biocompatibility. Surfaces modified with end-tethered poly(ethylene oxide) (PEO) have been shown to be protein-resistant to some degree. Although the mechanisms are unclear, it has been suggested that chain length, chain density, and chain conformation are important factors. To investigate the effects of PEO chain density, we selected a model system based on the chemisorption of chain-end thiolated PEO to a gold substrate. Chain density was varied by varying PEO solubility (proximity to cloud point) and incubation time in the chemisorption solution. The adsorption of fibrinogen and lysozyme to these surfaces was investigated. It was found that for 750 and 2000 MW PEO layers, resistance to fibrinogen increased with chain density and was maximal at a density of ~0.5 chains/nm2 (80% decrease in adsorption compared to unmodified gold). As PEO chain density increased beyond 0.5/nm2 adsorption increased. For PEO of 5000 MW the optimal chain density was 0.27/nm2 and gave only a 60% reduction in fibrinogen adsorption. It is suggested that, at high chain density, the chemisorbed PEO is dehydrated giving a surface that is no longer protein resistant. The PEO-modified surfaces were found also to be resistant to lysozyme adsorption with reductions similar to, if somewhat less than, those for fibrinogen. The fibrinogen to lysozyme molar ratios were within the expected range for close-packed layers of these proteins in their native conformation and were relatively insensitive to PEO chain density and MW. This may suggest that such adsorption as did occur, even at chain densities giving minimum adsorption, may have been on patches of unmodified gold.
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LanguageEnglish
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Identifier10367391
NPARC number12328156
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Record identifier1f0081bd-3c2b-4519-9941-53b77ea7303a
Record created2009-09-10
Record modified2016-05-09
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