School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK.
Nanoscale. 2018 Sep 13;10(35):16902-16910. doi: 10.1039/c8nr03870h.
Polymer-based multilayer microencapsulation technology represents one of the promising strategies for intracellular drug delivery, however, membrane processes involved in vehicle internalisation are not fully understood. Here we employed a scanning probe microscopy technique called Scanning Ion Conductance Microscopy (SICM) to study these complex processes at nanoscale resolution in real time. We were able to image topography simultaneously with local elastic modulus throughout the whole course of microcapsule internalisation in A549 cell culture without disrupting the internalisation process. The imaging revealed that capsules triggered the formation of membrane protrusions in their vicinity, which is an important but not a sufficient step towards full capsule internalisation. A crucial aspect appeared to be nanoscale restructuring of these protrusions into smooth thin layers extending over the surface of capsules. Simultaneous mapping of elastic modulus during capsule internalisation allowed monitoring the structural changes during extension of the membrane sheets over the surface of the capsule and the subsequent post-internalisation phenomenon of capsule buckling. To our knowledge these are the first experimental data capturing the interactions between the cellular membrane and microcapsules in their whole complexity with nanoscale resolution. The methodology established here has the potential to provide new insights into interactions at the interface between the nanostructured materials and cellular membrane under physiological conditions.
基于聚合物的多层微胶囊技术是一种很有前途的细胞内药物输送策略，然而，对于载体内化所涉及的膜过程还不完全清楚。在这里，我们采用了一种称为扫描离子电导显微镜（SICM）的扫描探针显微镜技术，实时以纳米级分辨率研究这些复杂的过程。我们能够在不干扰内化过程的情况下，对整个微胶囊内化过程中的局部弹性模量进行实时成像。成像显示，胶囊在其附近引发了膜突起的形成，这是完全内化的重要但非充分步骤。一个关键方面似乎是这些突起在纳米尺度上的重构，形成延伸到胶囊表面的光滑薄层。在胶囊内化过程中同时进行弹性模量映射，可以监测在膜片在胶囊表面延伸过程中的结构变化，以及随后的胶囊内陷后现象。据我们所知，这些是首次以纳米级分辨率捕捉到完整细胞内复杂相互作用的实验数据。这里建立的方法有可能为在生理条件下，纳米结构材料与细胞膜之间的界面相互作用提供新的见解。
