The project has mostly developed according to plans. First, we developed major pieces of instrumentation enabling the access to new experimental conditions to conduct Dynamic Nuclear Polarization (DNP) under high resolution condition (MAS, magic angle spinning). This is achieved using pressurized cold helium gas to spin and cool the sample down to cryogenic temperature while conducting in situ irradiation at the sample using suitable microwave irradiation, resulting in much higher overall sensitivity than using commercial equipment. We aim to transfer the technology developed within the core of this project to an industrial partner and to install similar systems in other research laboratories.
Second, we also made significant progress (both theoretically and experimentally) in the in depth understanding of the hyper-polarization transfer at stake during dynamic nuclear polarization, which led us to the design of improved polarizing agent molecules. The latter molecules belong to a class of paramagnetic dopants and are used as source of polarization in DNP experiments. Thanks to the in situ microwave irradiation, the electron polarization is transferred to the surrounding nuclei, boosting the sensitivity of NMR experiments by several orders of magnitude.
The improvement in sensitivity were used to conduct new NMR experiments, out of reach using conventional NMR. We notably showed that structural information (e.g. internuclei distances) can be extracted from data recorded on organic nano-assemblies and more generally powdered solids, without requiring the use of isotopic enrichment. This approach was also extended to the study of protein aggregates (involved in Huntington diseases), paving the way to NMR studies on patient or animal-derived materials.
We have also demonstrated a new approach, called Sel-DNP, to selectively detect hyperpolarize protein binding sites using high resolution DNP-enhanced NMR. This method relies on the combined use of functionalized ligand and difference spectroscopy and yield resolved multidimensional NMR spectra of selected parts of a biomolecular assembly. In our first work, we showed that this could be used on a carbohydrate binding protein to locate and assign the binding site without previous knowledge of the system.
