Biozentrum and the Swiss Nanoscience Institute, University of Basel, Klingelbergstrasse 50/70 CH - 4056, Basel, Switzerland.
Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK.
Nat Nanotechnol. 2014 Jul;9(7):525-30. doi: 10.1038/nnano.2014.103. Epub 2014 Jun 15.
The selectivity and speed of many biological transport processes transpire from a 'reduction of dimensionality' that confines diffusion to one or two dimensions instead of three. This behaviour remains highly sought after on polymeric surfaces as a means to expedite diffusional search processes in molecular engineered systems. Here, we have reconstituted the two-dimensional diffusion of colloidal particles on a molecular brush surface. The surface is composed of phenylalanine-glycine nucleoporins (FG Nups)--intrinsically disordered proteins that facilitate selective transport through nuclear pore complexes in eukaryotic cells. Local and ensemble-level experiments involving optical trapping using a photonic force microscope and particle tracking by video microscopy, respectively, reveal that 1-µm-sized colloidal particles bearing nuclear transport receptors called karyopherins can exhibit behaviour that varies from highly localized to unhindered two-dimensional diffusion. Particle diffusivity is controlled by varying the amount of free karyopherins in solution, which modulates the multivalency of Kap-binding sites within the molecular brush. We conclude that the FG Nups resemble stimuli-responsive molecular 'velcro', which can impart 'reduction of dimensionality' as a means of biomimetic transport control in artificial environments.
许多生物转运过程的选择性和速度都源于“维度降低”，这种现象将扩散限制在一到两个维度，而不是三个维度。这种行为在聚合物表面上仍然备受关注，因为它是加速分子工程系统中扩散搜索过程的一种手段。在这里，我们在分子刷表面上重新构建了胶体颗粒的二维扩散。该表面由苯丙氨酸-甘氨酸核孔蛋白（FG Nups）组成，FG Nups 是一种内在无序的蛋白质，可促进真核细胞中核孔复合物的选择性转运。涉及使用光子力显微镜进行光学捕获的局部和整体实验以及通过视频显微镜进行的粒子跟踪，分别揭示了 1 微米大小的胶体颗粒可以表现出从高度局部化到无障碍二维扩散的行为，这些胶体颗粒带有称为核转运受体的核孔蛋白。粒子扩散率可以通过改变溶液中游离核孔蛋白的数量来控制，这可以调节分子刷内 Kap 结合位点的多价性。我们得出的结论是，FG Nups 类似于对刺激有反应的分子“魔术贴”，它可以作为仿生运输控制的一种手段，在人工环境中实现“维度降低”。
