Fluorescent diamond nanoparticle: an innovating probe to study macromolecular organization and trafficking in neurons – NeuroDiam

The NEURODIAM project aims at studying macromolecular organization and trafficking in neurons using a new fluorescent nanoparticle probe relying on functionalized fluorescent nanodiamond (fND), which have the remarkable properties of a perfectly stable fluorescence and an optically detected electron-spin resonance at room temperature.

Four teams are involved in this multidisciplinary project :
* Two Taiwanese teams:
- Huan-Cheng CHANG's team at the Institute of Atomic and Molecular Science (IAMS), belonging to Academia Sinica, Taipei (Taiwan)
- Chih-Che (Eric) WU's team from Department of Applied Chemistry at the National Chi Nan University (NCNU), in Nantou (Taiwan)
* Two French teams
- François TREUSSART's team at Laboratoire de Photonique Quantique et Moléculaire (UMR CNRS 8537) in ENS Cachan
- Michel SIMONNEAU's team from Centre de Psychiatrie et Neurosciences (INSERM U894, & Univ. Paris Descartes), in Paris.
The complementary expertises of these teams are in nanobiotechnology, surface functionalization applied to nanosciences, nanophotonics, molecular genetics applied to neurosciences, respectively.

The project uses a unique combination of novel high-resolution fluorescent microscopies and of the fluorescent nanodiamonds functionnalized to interact with genetically engineered neuronal proteins in order to gain novel information on neuronal functions.
We selected to study neuronal functions that are known to be deregulated in various neuropsychiatric and neurodegeneratives diseases, having a high prevalence and being important societal burdens.

The project aims to study three neuronal functions that are known to be deregulated in psychiatric and neurodegenerative disorders:
- dendritic trafficking
- dendritic spine morphology changes linked to synaptic plasticity
- retrograde axonal trafficking.
Dendritic trafficking and dendritic spine plasticity are modified in psychiatric diseases. Dendritic spine plasticity is abnormal in early steps of Alzheimer disease. Retrograde axonal trafficking was also found abnormal in animal models of Alzheimer and Down’s disease.

A significant part of the project, participating to its originality, will also be devoted to the development and optimization of the super-resolution imaging techniques. In this project we will develop simultaneously a conventional STED microscopes and a complementary high-resolution imaging technique to STED, which can distinguish individual fNDs, relying on the other remarkable properties of NV-, which is to possess an electron spin resonance (ESR), in the microwave domain (2.87 GHz) that can be optically detected. This property allows optical detection of Magnetic Resonance of NV- center (NV-MRI) in a magnetic field gradient. Two super-resolution imaging, STED and NV-MRI will be developed in parallel with performance allowing the analysis of the macromolecular organization inside dendritic spines.

The original key point of this project is its multidisciplinarity. It combines:
- state-of-the-art methodologies in novel microscopies (STED and optically detected magnetic resonance)
- nanodiamonds as fluorescent nanoparticles
- functionalization using biotin
- genetical engineering of proteins of interest in order to use the tight binding of biotin to streptavidin