Steiner Gerald, Tunc Sibel, Maitz Manfred, Salzer Reiner
Institute for Analytical Chemistry, Dresden University of Technology, 01062 Dresden, Germany.
Anal Chem. 2007 Feb 15;79(4):1311-6. doi: 10.1021/ac061341j.
The influence of hydrophobicity of the substrate surface on structural changes during protein adsorption was investigated. Plasma fibrinogen was chosen to model this effect as it is the most important protein in the body that adsorbs to foreign surfaces. Only conformations of adsorbed fibrinogen similar to that of the protein in solution do not activate the process of blood coagulation. Small spots on the substrate surface with conformational changes within the adsorbed protein are already sufficient to deteriorate biocompatibility. Mid-infrared hyperspectral imaging permits the identification of coagulated spots down to a few micrometers in size. The spectra of the FT-IR images that were assessed to be of suitable quality were clustered by a fuzzy c-means algorithm. The determination of the appropriate number of clusters was based on cluster variance. Subsequent evaluation of the centroid spectra of each cluster showed that their amide I band was separated into contributions from different structural units, with the alpha-helix content always being dominant. Significant differences between hydrophobic and hydrophilic surfaces were observed for turn and sheet contributions. Lower sheet/turn ratios appear to indicate inferior biocompatibility. Spots on hydrophilic surfaces could be identified, which exhibit structural changes similar to those on hydrophobic surfaces.
研究了底物表面疏水性对蛋白质吸附过程中结构变化的影响。选择血浆纤维蛋白原作为模拟这种效应的模型，因为它是体内吸附到异物表面的最重要蛋白质。只有吸附的纤维蛋白原的构象与溶液中蛋白质的构象相似时，才不会激活血液凝固过程。底物表面上吸附蛋白质内具有构象变化的小斑点就足以降低生物相容性。中红外高光谱成像能够识别尺寸小至几微米的凝固斑点。通过模糊c均值算法对评估为质量合适的傅里叶变换红外（FT-IR）图像的光谱进行聚类。聚类数量的确定基于聚类方差。随后对每个聚类的质心光谱进行评估，结果表明它们的酰胺I带被分离为来自不同结构单元的贡献，其中α-螺旋含量始终占主导。对于转角和片层的贡献，观察到疏水表面和亲水表面之间存在显著差异。较低的片层/转角比似乎表明生物相容性较差。可以识别亲水表面上的斑点，其表现出与疏水表面上类似的结构变化。
