Protein resistance of surfaces prepared by sorption of end-thiolated poly(ethylene glycol) to gold: Effect of surface chain density
Protein resistance of surfaces prepared by sorption of end-thiolated poly(ethylene glycol) to gold: Effect of surface chain density
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DOI：
10.1021/la047672d
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发表时间：
2005-02-01
期刊：
影响因子：
3.9
通讯作者：
Brash, JL
中科院分区：
文献类型：
--
作者：
Unsworth, LD;Sheardown, H;Brash, JL
非特异性蛋白质吸附通常发生在生物材料-组织界面处，并且通常具有不良后果。因此，迫切寻求蛋白质抗性的表面，期望这些材料将表现出改善的生物相容性。用末端栓系的聚（环氧乙烷）（PEO）改性的表面已被证明在一定程度上是抗蛋白质的。虽然其机制尚不清楚，但已表明链长、链密度和链构象是重要因素。为了研究PEO链密度的影响，我们选择了一个模型系统的基础上的化学吸附链端硫醇化的PEO的金基板。通过改变PEO溶解度（接近浊点）和在化学吸附溶液中的孵育时间来改变链密度。纤维蛋白原和溶菌酶的吸附这些表面进行了研究。结果发现，对于750和2000 MW的PEO层，对纤维蛋白原的抵抗力随着链密度的增加而增加，并且在接近0.5链/nm（2）的密度时达到最大（与未改性的金相比，吸附减少80%）。当PEO链密度增加超过0.5/nm（2）时，吸附增加。对于5000 MW的PEO，最佳链密度为0.27/nm（2），并且仅使纤维蛋白原吸附减少60%。有人建议，在高链密度下，化学吸附的PEO被脱水，从而使表面不再具有蛋白质抗性。PEO改性的表面也被发现是耐溶菌酶吸附减少类似，如果稍微小于，那些纤维蛋白原。纤维蛋白原与溶菌酶的摩尔比在预期范围内，这些蛋白质在其天然构象的紧密堆积层，PEO链密度和MW相对不敏感。这可能表明，即使在链密度达到最小吸附量时，这种吸附也可能发生在未改性的金片上。
Nonspecific 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 similar to0.5 chains/nm(2) (80% decrease in adsorption compared to unmodified gold). As PEO chain density increased beyond 0.5/nm(2) adsorption increased. For PEO of 5000 MW the optimal chain density was 0.27/nm(2) 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.