Linke G T, Lipowsky R, Gruhn T
Max Planck Institute of Colloids and Interfaces, Science Park Golm, D-14424 Potsdam, Germany.
Eur Phys J E Soft Matter. 2007 Nov;24(3):217-27. doi: 10.1140/epje/i2007-10232-2. Epub 2007 Nov 29.
The adhesion of fluid vesicles at chemically structured substrates is studied theoretically via Monte Carlo simulations. The substrate surface is planar and repels the vesicle membrane apart from a single surface domain gamma , which strongly attracts this membrane. If the vesicle is larger than the attractive gamma domain, the spreading of the vesicle onto the substrate is restricted by the size of this surface domain. Once the contact line of the adhering vesicle has reached the boundaries of the gamma domain, further deflation of the vesicle leads to a regime of low membrane tension with pronounced shape fluctuations, which are now governed by the bending rigidity. For a circular gamma domain and a small bending rigidity, the membrane oscillates strongly around an average spherical cap shape. If such a vesicle is deflated, the contact area increases or decreases with increasing osmotic pressure, depending on the relative size of the vesicle and the circular gamma domain. The lateral localization of the vesicle's center of mass by such a domain is optimal for a certain domain radius, which is found to be rather independent of adhesion strength and bending rigidity. For vesicles adhering to stripe-shaped surface domains, the width of the contact area perpendicular to the stripe varies nonmonotonically with the adhesion strength.
通过蒙特卡罗模拟从理论上研究了流体囊泡在化学结构化基底上的粘附情况。基底表面是平面的，除了一个强烈吸引囊泡膜的单一表面区域γ外，它排斥囊泡膜。如果囊泡大于吸引性的γ区域，囊泡在基底上的铺展受到该表面区域大小的限制。一旦粘附囊泡的接触线到达γ区域的边界，囊泡的进一步收缩会导致膜张力较低且形状波动明显的状态，此时形状波动由弯曲刚度决定。对于圆形的γ区域和较小的弯曲刚度，膜会围绕平均球冠形状剧烈振荡。如果这样一个囊泡收缩，接触面积会随着渗透压的增加而增加或减少，这取决于囊泡和圆形γ区域的相对大小。对于某个区域半径，囊泡质心通过这样一个区域的横向定位是最佳的，发现该半径相当独立于粘附强度和弯曲刚度。对于粘附在条纹状表面区域的囊泡，垂直于条纹的接触区域宽度随粘附强度非单调变化。
