Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado 80309, USA.
J Am Chem Soc. 2011 Apr 6;133(13):4975-83. doi: 10.1021/ja110663u. Epub 2011 Mar 10.
Through the use of single-molecule total internal reflection fluorescence microscopy, the dynamic behavior of fibrinogen was observed at the interface between aqueous solution and various solid surfaces. Multiple populations of objects were observed, as characterized by surface residence times, interfacial diffusion, and fluorescence intensity. On all surfaces, populations exhibited direct links between surface residence time, rate of diffusion, and fluorescence intensity. In particular, longer-lived populations diffused more slowly and exhibited greater fluorescence intensity, leading to the conclusion that the objects represented fibrinogen monomers and discrete oligomer populations (dimers, trimers, etc.), and that these oligomer populations play an important role in the protein-surface interaction because of their long surface residence times. Two or three diffusive modes were observed for most populations, indicating that protein aggregates have multiple mechanisms for interaction with solid substrates. In addition, the fastest diffusive mode is believed to represent a hopping mode that often precedes desorption events. Surprisingly, a monolayer of 5000 Da poly(ethylene glycol) (PEG5000) increased surface residence time and slowed diffusion of fibrinogen relative to bare fused silica or hydrophobically modified fused silica, suggesting that the mechanism of PEG resistance to protein adhesion is more sophisticated than the simple repulsion of individual proteins.
通过使用单分子全内反射荧光显微镜，在水溶液和各种固体表面之间的界面处观察到了纤维蛋白原的动态行为。观察到了多个物体群体，其特征是表面停留时间、界面扩散和荧光强度。在所有表面上，群体表现出表面停留时间、扩散速率和荧光强度之间的直接联系。特别是，寿命较长的群体扩散速度较慢，荧光强度较大，这表明这些物体代表纤维蛋白原单体和离散的低聚物群体（二聚体、三聚体等），并且这些低聚物群体在蛋白质-表面相互作用中起着重要作用，因为它们具有较长的表面停留时间。大多数群体观察到了两种或三种扩散模式，这表明蛋白质聚集体与固体底物相互作用有多种机制。此外，最快的扩散模式被认为代表了一种跳跃模式，这种模式通常先于解吸事件发生。令人惊讶的是，5000 道尔顿的聚乙二醇（PEG5000）单层与裸露的熔融二氧化硅或疏水性改性的熔融二氧化硅相比，增加了纤维蛋白原的表面停留时间并减缓了其扩散，这表明 PEG 抵抗蛋白质粘附的机制比单个蛋白质的简单排斥更为复杂。
