Optical detection of individual ultra-short carbon nanotubes enables their length characterization down to 10 nm

Ultrashort single-walled carbon nanotubes, i.e. with length below ~30 nm, display length-dependent physical, chemical and biological properties that are attractive for the development of novel nanodevices and nanomaterials. Whether fundamental or applicative, such developments require that ultrashort nanotube lengths can be routinely and reliably characterized with high statistical data for high-quality sample production. However, no methods currently fulfill these requirements. Here, we demonstrate that photothermal microscopy achieves fast and reliable optical single nanotube analysis down to ~10 nm lengths. Compared to atomic force microscopy, this method provides ultrashort nanotubes length distribution with high statistics, and neither requires specific sample preparation nor tip-dependent image analysis. Ultrashort single-walled carbon nanotubes (usCNTs) hold unique physical, chemical and biological properties that can be used for applications in diverse areas. In condensed matter physics, both theory and experiments have shown that the nanotube electronic band-gap increases as their length shortens down to tens of nanometers in response to quantum confinement effect along the length axisNanotubes de carbone ultra-courts : des nano-marqueurs proche-infrarouges pour le suivi de biomolécules dans des tissus vivants du cerveau.Outils pour la quantification tissulaire par imagerie: Histopathologie à haut contenu de tissus humains et artificielsDéveloppment d'une infrastructure française distribuée coordonnéeInitiative d'excellence de l'Université de Bordeau

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

This work was supported by CNRS, the Agence Nationale de la Recherche (ANR-14-OHRI-0001-01), IdEx Bordeaux (ANR-10-IDEX-03-02), Labex Brain (ANR-10-LABX-43), Conseil Régional d'Aquitaine (2011-1603009) and the France-BioImaging national infrastructure (ANR-10-INBS-04-01). A.G.G. acknowledges financial support from the Fondation pour la Recherche Médicale and the Fonds Recherche du Québec–Nature et Technologies. J.A.V. acknowledges funding from Marie Curie Individual Fellowship 326442.The brain is a dynamic structure with the extracellular space (ECS) taking up almost a quarter of its volume. Signalling molecules, neurotransmitters and nutrients transit via the ECS, which constitutes a key microenvironment for cellular communication and the clearance of toxic metabolites. The spatial organization of the ECS varies during sleep, development and aging and is probably altered in neuropsychiatric and degenerative diseases, as inferred from electron microscopy and macroscopic biophysical investigations. Here we show an approach to directly observe the local ECS structures and rheology in brain tissue using super-resolution imaging. We inject single-walled carbon nanotubes into rat cerebroventricles and follow the near-infrared emission of individual nanotubes as they diffuse inside the ECS for tens of minutes in acute slices. Because of the interplay between the nanotube geometry and the ECS local environment, we can extract information about the dimensions and local viscosity of the ECS. We find a striking diversity of ECS dimensions down to 40 nm, and as well as of local viscosity values. Moreover, by chemically altering the extracellular matrix of the brains of live animals before nanotube injection, we reveal that the rheological properties of the ECS are affected, but these alterations are local and inhomogeneous at the nanoscale.PostprintPeer reviewe