Single-nanotube tracking reveals the nanoscale organization of the extracellular space in the live brain

Antoine G. Godin (1) , Juan A. Varela (2) , Zhenghong Gao (3) , Noémie Danné (4) , Julien P. Dupuis (2) , Brahim Lounis (3) , Laurent Groc (2) , Laurent Cognet (4)

1 lp2n-04,lp2n-12
2 IINS - Interdisciplinary Institute for Neuroscience [Bordeaux]
3 lp2n-01,lp2n-12
4 LP2N - Laboratoire Photonique, Numérique et Nanosciences

The brain is a dynamic structure in which the extracellular space (ECS) takes up 14 almost a quarter of its volume 1-2. Signalling molecules, neurotransmitters and nutrients 15 transit via the ECS which constitutes a key microenvironment for cellular communication 3 16 and clearance of toxic metabolites. The ECS spatial organization varies during sleep 4 , 17 development 5 , aging 6 and is likely altered in neuropsychiatric and degenerative diseases 7 , 18 as inferred from electron microscopy 8-9 and macroscopic biophysical investigations 2,10. 19 Here we show an approach to directly observe the local ECS structures and rheology in a 20 brain tissue using super-resolution imaging. We inject single-walled carbon nanotubes 21 (SWCNTs) in rat cerebroventricles and follow individual nanotubes near-IR emission for 22 tens of minutes in acute slices as they diffuse inside the ECS. Because of the interplay 23 between the nanotube geometry and the ECS local environment, we can extract 24 information about the ECS dimension and local viscosity. We find a striking diversity of 25 ECS dimensions down to 40 nm, and as well as of local viscosity values. Moreover, by 26

Domaines: Optique [physics.optics]; Biophysique [physics.bio-ph]; Neurosciences [q-bio.NC]

Antoine G. Godin, Juan A. Varela, Zhenghong Gao, Noémie Danné, Julien P. Dupuis, et al.. Single-nanotube tracking reveals the nanoscale organization of the extracellular space in the live brain. Nature Nanotechnology, 2016, 12 (3), pp.238 - 243. ⟨10.1038/NNANO.2016.248⟩. ⟨hal-01630795⟩