Flow-induced adhesion of shear-activated polymers to a substrate
Flow-induced adhesion of shear-activated polymers to a substrate
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DOI：
10.1088/1361-648x/aaa4d5
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发表时间：
2018-02
期刊：
影响因子：
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通讯作者：
Masoud Hoore;K. Rack;D. Fedosov;G. Gompper
中科院分区：
文献类型：
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作者：
Masoud Hoore;K. Rack;D. Fedosov;G. Gompper
聚合物和蛋白质对基材的粘附在许多技术应用和生物过程中起着至关重要的作用。一个突出的例子是冯·维勒布兰德因子 (VWF) 蛋白，它对于血液凝固至关重要，因为它在高剪切速率下介导血小板与损伤部位的粘附。 VWF 被流动激活，即使在极端的流动应力条件下也能够有效地结合受损的血管壁；然而，当流动强度显着降低或流动停止时，其粘附力是可逆的。受 VWF 在流动中的性质和行为的启发，我们研究了剪切激活聚合物在流动中对平面壁的粘附，以及这种粘附在流动停滞下是否可逆。聚合物模型的主要成分是单体间的内聚相互作用、与粘合剂表面的捕获键以及与其流动拉伸相关的聚合物粘合的剪切活化/失活。聚合物内的内聚相互作用在低剪切应力下保持球状构象，并且如果超过临界剪切速率则允许聚合物拉伸，这与其粘附激活直接相关。我们的结果表明，高剪切速率下的聚合物粘附通过捕捉键显着稳定，同时它们还允许聚合物在低流动应力或无流动应力下从表面解离。此外，粘附的激活/失活机制对其粘附的可逆性起着至关重要的作用。这些观察结果有助于我们更好地了解 VWF 在血流中的粘附行为，并解释其在 VWF 相关疾病中的粘附功能障碍。
Adhesion of polymers and proteins to substrates plays a crucial role in many technological applications and biological processes. A prominent example is the von Willebrand factor (VWF) protein, which is essential in blood clotting as it mediates adhesion of blood platelets to the site of injury at high shear rates. VWF is activated by flow and is able to bind efficiently to damaged vessel walls even under extreme flow-stress conditions; however, its adhesion is reversible when the flow strength is significantly reduced or the flow is ceased. Motivated by the properties and behavior of VWF in flow, we investigate adhesion of shear-activated polymers to a planar wall in flow and whether the adhesion is reversible under flow stasis. The main ingredients of the polymer model are cohesive inter-monomer interactions, a catch bond with the adhesive surface, and the shear activation/deactivation of polymer adhesion correlated with its stretching in flow. The cohesive interactions within the polymer maintain a globular conformation under low shear stresses and allow polymer stretching if a critical shear rate is exceeded, which is directly associated with its activation for adhesion. Our results show that polymer adhesion at high shear rates is significantly stabilized by catch bonds, while at the same time they also permit polymer dissociation from a surface at low or no flow stresses. In addition, the activation/deactivation mechanism for adhesion plays a crucial role in the reversibility of its adhesion. These observations help us better understand the adhesive behavior of VWF in flow and interpret its adhesion malfunctioning in VWF-related diseases.