Dupont-Gillain Christine C, Jacquemart Isabelle, Rouxhet Paul G
Unité de Chimie des Interfaces, Université Catholique de Louvain, Croix du Sud 2/18, 1348 Louvain-la-Neuve, Belgium.
Colloids Surf B Biointerfaces. 2005 Jul 10;43(3-4):179-86. doi: 10.1016/j.colsurfb.2004.12.022.
In the last years, adsorbed collagen was shown to form layers with a supramolecular organization depending on the substrate surface properties and on the preparation procedure. If the concentration of collagen and the duration of adsorption are sufficient, fibrillar collagen structures are formed, corresponding to assemblies of a few molecules. This occurs more readily on hydrophobic compared to hydrophilic surfaces. This study aims at understanding the origin of such fibrillar structures and in particular at determining whether they result from the deposition of fibrils formed in solution or from the building of assemblies at the interface. Therefore, type I collagen solutions with an increasing degree of aggregation were prepared, using the "neutral-start" approach, by ageing pH 5.8 solutions at 37 degrees C for 15 min, 2 or 7 days. The obtained solutions were used to investigate the influence of collagen aggregation in solution on the supramolecular organization of adsorbed collagen layers, which was characterized by X-ray photoelectron spectroscopy and atomic force microscopy. Polystyrene and plasma-oxidized polystyrene were chosen as substrates for the adsorption. The size and the density of collagen fibrils at the interface decreased upon increasing the degree of aggregation of collagen in solution. This is explained by a competitive adsorption process between monomers and aggregates of the solution, turning at the advantage of the monomers. More aggregated solutions, which are thus depleted in free monomers, behave like less concentrated solutions, i.e. lead to a lower adsorbed amount and less fibril formation at the interface. This study shows that the supramolecular fibrils observed in adsorbed collagen layers, especially on hydrophobic substrates, are not formed in the solution, prior to adsorption, but are built at the interface, through the assembly of free segments of adsorbed molecules.
在过去几年中，已表明吸附的胶原蛋白会根据底物表面性质和制备程序形成具有超分子结构的层。如果胶原蛋白的浓度和吸附持续时间足够，就会形成纤维状胶原蛋白结构，这对应于少数分子的组装。与亲水性表面相比，这种情况在疏水性表面上更容易发生。本研究旨在了解这种纤维状结构的起源，特别是确定它们是由溶液中形成的纤维沉积产生的，还是由界面处的组装形成的。因此，采用“中性起始”方法，通过在37℃下将pH 5.8的溶液老化15分钟、2天或7天，制备了聚集程度不断增加的I型胶原蛋白溶液。所得溶液用于研究溶液中胶原蛋白聚集对吸附胶原蛋白层超分子结构的影响，通过X射线光电子能谱和原子力显微镜对其进行表征。选择聚苯乙烯和等离子体氧化的聚苯乙烯作为吸附底物。随着溶液中胶原蛋白聚集程度的增加，界面处胶原蛋白纤维的尺寸和密度减小。这可以通过溶液中单体和聚集体之间的竞争吸附过程来解释，结果有利于单体。聚集程度更高的溶液，即游离单体含量较低的溶液，其行为类似于浓度较低的溶液，即在界面处导致较低的吸附量和较少的纤维形成。这项研究表明，在吸附的胶原蛋白层中观察到的超分子纤维，尤其是在疏水性底物上，不是在吸附前在溶液中形成的，而是通过吸附分子自由片段的组装在界面处形成的。
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