Leduc C, Depaola N, Konath S, Vroman L, Leonard E F
Department of Chemical Engineering, Materials Science and Mining, Columbia University, New York, NY 10027.
J Biomater Sci Polym Ed. 1994;6(7):599-608. doi: 10.1163/156856294x00545.
Perturbations in the adsorption of plasma proteins caused by flow separation were studied quantitatively. An instrument was constructed that causes flow to separate over approximately half the width of a standard microscope slide and the pattern of protein deposition in and near the separated flow was observed by staining the slide with black iron oxide. The slide was mounted at the edge of a Couette flow field established between two concentric cylinders, the outer of which was rotating. The slide was located on the stationary, inner cylinder just downstream of a rectangular bar that causes the flow to separate. After exposure to dilute plasma injected upstream of the bar, the slide was removed and stained with oxide suspension. The resulting, visible pattern was scanned through a video camera and analyzed to yield relative values of stain density that could be quantified. The oxide patterns suggest that proteins were deposited onto the slide less rapidly in and just downstream of the separated flow region than farther downstream. At a shear rate of 6.61 s-1, corresponding to a velocity of 1.32 cm s-1 0.2 cm above the point of flow separation, overall amounts of adsorbed proteins increased with exposure time in the range 3-30 min with the exception of a period from 10 to 11 min when all data show a temporary decrease. In calibration experiments, oxide failed to adhere to slides exposed to purified albumin but adhered copiously to slides exposed to purified fibrinogen. These results suggest that the oxide patterns following plasma exposure are attributable primarily to fibrinogen and that the temporary decrease in the separated flow experiments is attributable to the displacement of fibrinogen by a less stainable protein, conjecturally high molecular weight kininogen and factor XII. This study yields quantitative information confirming earlier findings that were less controlled and non-quantitative. It confirms the hypothesis that the sequence of protein deposition from dilute plasma to glass surfaces is delayed in regions of separated flow.
对由流动分离引起的血浆蛋白吸附扰动进行了定量研究。构建了一种仪器，该仪器使流动在标准显微镜载玻片约一半宽度上分离，并通过用黑色氧化铁对载玻片染色来观察分离流中及附近的蛋白质沉积模式。载玻片安装在两个同心圆柱之间建立的库埃特流场的边缘，其中外部圆柱在旋转。载玻片位于固定的内部圆柱上，就在导致流动分离的矩形条的下游。在暴露于在条上游注入的稀释血浆后，取出载玻片并用氧化物悬浮液染色。通过摄像机扫描得到的可见图案并进行分析，以得出可量化的染色密度相对值。氧化物图案表明，在分离流区域内及紧下游，蛋白质沉积到载玻片上的速度比更远的下游要慢。在剪切速率为6.61 s-1时，对应于在流动分离点上方0.2 cm处1.32 cm s-1的速度，除了在10至11分钟期间所有数据显示暂时下降外，在3至30分钟范围内，吸附蛋白质的总量随暴露时间增加。在校准实验中，氧化物未能附着在暴露于纯化白蛋白的载玻片上，但大量附着在暴露于纯化纤维蛋白原的载玻片上。这些结果表明，血浆暴露后的氧化物图案主要归因于纤维蛋白原，并且分离流实验中的暂时下降归因于纤维蛋白原被一种染色性较低的蛋白质（推测为高分子量激肽原和因子XII）所取代。这项研究产生了定量信息，证实了早期控制较少且非定量的研究结果。它证实了这样的假设，即在分离流区域，从稀释血浆到玻璃表面的蛋白质沉积顺序会延迟。
