van der Wel Casper, Heinrich Doris, Kraft Daniela J
Biological and Soft Matter Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, Leiden, the Netherlands.
Biological and Soft Matter Physics, Huygens-Kamerlingh Onnes Laboratory, Leiden University, Leiden, the Netherlands; Fraunhofer Institute for Silicate Research, Würzburg, Germany.
Biophys J. 2017 Sep 5;113(5):1037-1046. doi: 10.1016/j.bpj.2017.07.019.
Understanding interactions between microparticles and lipid membranes is of increasing importance, especially for unraveling the influence of microplastics on our health and environment. Here, we study how a short-ranged adhesive force between microparticles and model lipid membranes causes membrane-mediated particle assembly. Using confocal microscopy, we observe the initial particle attachment to the membrane, then particle wrapping, and in rare cases spontaneous membrane tubulation. In the attached state, we measure that the particle mobility decreases by 26%. If multiple particles adhere to the same vesicle, their initial single-particle state determines their interactions and subsequent assembly pathways: 1) attached particles only aggregate when small adhesive vesicles are present in solution, 2) wrapped particles reversibly attract one another by membrane deformation, and 3) a combination of wrapped and attached particles form membrane-mediated dimers, which further assemble into a variety of complex structures. The experimental observation of distinct assembly pathways, induced only by a short-ranged membrane-particle adhesion, shows that a cytoskeleton or other active components are not required for microparticle aggregation. We suggest that this membrane-mediated microparticle aggregation is a reason behind reported long retention times of polymer microparticles in organisms.
了解微粒与脂质膜之间的相互作用变得越来越重要，特别是对于揭示微塑料对我们健康和环境的影响。在此，我们研究微粒与模型脂质膜之间的短程粘附力如何导致膜介导的颗粒组装。使用共聚焦显微镜，我们观察到颗粒最初附着在膜上，然后是颗粒包裹，在极少数情况下会出现自发的膜微管形成。在附着状态下，我们测量到颗粒的迁移率降低了26%。如果多个颗粒附着在同一个囊泡上，它们最初的单颗粒状态决定了它们的相互作用和随后的组装途径：1）只有当溶液中存在小的粘附性囊泡时，附着的颗粒才会聚集；2）包裹的颗粒通过膜变形相互可逆吸引；3）包裹和附着颗粒的组合形成膜介导的二聚体，进而组装成各种复杂结构。仅由短程膜-颗粒粘附诱导的不同组装途径的实验观察表明，微粒聚集不需要细胞骨架或其他活性成分。我们认为这种膜介导的微粒聚集是报道的聚合物微粒在生物体中长时间保留的原因之一。
