NanoHeadTail · Head to tail imaging of fluorescent carbon nanotubes for the characterization of the brain extracellular space

Head to tail imaging of fluorescent carbon nanotubes for the characterization of the brain extracellular space

In the "NanoHeadTail" project, we developed a new class of nanoprobes and combined it with state-of-the-art fluorescence microscopy to study the morphological and rheological properties of the brain extracellular space (ECS) at the nanoscale. Studying the ECS is critical as it is linked to a number of brain mechanisms, including some pathologies such as Parkinson’s disease. Previous studies have provided insights on the characteristics of the ECS but measured 2D trajectories and focused on the analysis of the translational diffusion properties of the probes. To overcome these limitations, we proposed to investigate the ECS using a new asymmetric nanoprobe based on the bi-functionalization of SWCNTs (bf-SWCNTs) with two fluorescent color centers (CCs) located at each end of the SWCNT (the “head” and the “tail”) and emitting at two distinct wavelengths. A custom-made microscope was envisioned to track the diffusion of individual bf-SWCNTs in 3D, thus allowing to to determine the characteristics of the ECS volume locally. To this end, the project followed two main scientific directions: 1) The functionalization of SWCNTs with CC and the characterization of the functionalized SWCNTs. The functionalization of carbon nanotubes with two different CCs necessitated a precise control of both the density of CCs and on the locations where CC form on the nanotube to avoid the creation of too many unwanted byproducts. Because, the CC functionalization reaction was poorly understood at the single nanotube level in the field and mostly viewed as stochastic, we dedicated the first part of this project to study the formation of CCs on individual SWCNTs. For that, an experiment has been designed to perform the functionalization reaction in situ while simultaneously resolving both the nanotube structure and the position of each CC forming in real time. This work lays the foundation of many future avenues for the functionalization of SWCNTs with CC, such as the bi-functionalization of SWCNTs with two CC types. 2) The analysis of SWCNT diffusion in 3D and in biological tissues. A custom super resolution microscopy setup was built for the tracking of the functionalized SWCNTs in 3D using a double helix phase mask. The tracking was performed on nanotubes functionalised with either aryl and oxygen CCs demonstrating that bi-functionalization is in principle possible. To improve even further the diffusion of SWCNTs in tissues, we tracked ultrashort functionalized nanotubes exhibiting lengths smaller by one order of magnitude compared to conventional nanotube probes. We performed the first demonstration of 3D single particle tracking of these ultrashort SWCNTs in brain organotypic slice.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз