PMID-27870840 Single-nanotube tracking reveals the nanoscale organization of the extracellular space in the live brain
- Extracellular space (ECS) takes up nearly a quarter the volume of the brain (!!!)
- Used the intrinsic fluorescence of single-walled carbon nanotubes @ 1um, 845nm excitation, with super-resolution tracking of diffusion.
- Were coated in phospholipid-polyethylene glycol (PL-PEG), which display low cytotoxicity compared to other encapsulants.
- 5ul, 3ug/ml injected into the ventricles of young rats; allowed to diffuse for 30 minutes post-injection.
- No apparent response of the microglia.
- Diffusion tracking revealed substantial dead-space domains in the ECS.
- As compared to patch-clamp loaded SWCNTs
- Estimate from parallel and perpendicular diffusion rates that the characteristic scale of ECS dimension is 80 to 270nm, or 150 +- 40nm.
- The ECS nanoscale dimensions as visualized by tracking similar in dimension and tortuosity to electron microscopy.
- Viscosity of the extracellular matrix from 1 to 50 mPa S, up to two orders of magnitude higher than the CSF.
- Positive control through hyalurinase + several hours to digest the hyaluronic acid.
- But no observed changes in morphology of the neurons via confocal .. interesting.
- Enzyme digestion normalized the spatial heterogenaity of diffusion.
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