The brain extracellular space (ECS) is a system of narrow compartments whose intricate nanometric structure has remained elusive until very recently. Understanding such a complex organisation represents a technological challenge that requires a technique able to resolve these nanoscopic spaces and simultaneously characterize their rheological properties. We recently used single-walled carbon nanotubes (SWCNTs) as near-infrared fluorescent probes to map with nanoscale precision the local organization and rheology of the ECS. Here we expand our method by tracking single nanotubes through super-resolution imaging in rat organotypic hippocampal slices and acute brain slices from adult mice, pioneering the exploration of the adult brain ECS at the nanoscale. We found a highly heterogeneous ECS, where local rheological properties can change drastically within few nanometres. Our results suggest differences in local ECS diffusion environments in organotypic slices when compared to adult mouse slices. Data obtained from super-resolved maps of the SWCNT trajectories indicate that ECS widths may vary between brain tissue models, with a looser, less crowded nano-environment in organotypic cultured slices.

中文翻译：

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通过结合单碳纳米管跟踪和超分辨率成像分析对活体大脑细胞外空间的纳米级探索

大脑细胞外空间 (ECS) 是一个狭窄的隔室系统，其复杂的纳米结构直到最近才难以捉摸。了解如此复杂的组织代表了一项技术挑战，需要一种能够解析这些纳米级空间并同时表征其流变特性的技术。我们最近使用单壁碳纳米管 (SWCNT) 作为近红外荧光探针，以纳米级精度绘制 ECS 的局部组织和流变学。在这里，我们通过大鼠器官海马切片和成年小鼠急性脑切片的超分辨率成像跟踪单个纳米管来扩展我们的方法，开创了在纳米尺度上探索成年大脑 ECS 的先河。我们发现了一个高度异构的 ECS，其中局部流变特性可以在几纳米内发生剧烈变化。我们的结果表明，与成年小鼠切片相比，器官切片中局部 ECS 扩散环境存在差异。从 SWCNT 轨迹的超分辨率图获得的数据表明，脑组织模型之间的 ECS 宽度可能会有所不同，在器官培养切片中，纳米环境更松散、不那么拥挤。