Maximising the sharing of the Nottingham DNP MAS NMR Facility

The Nottingham DNP MAS Facility was established in 2015 via an EPSRC strategic equipment application jointly submitted by the Schools of Physics, Chemistry and Life Sciences. Since its implementation access to the Facility could be gained through two different routes. Costed access required the payment of the FEC operating costs (£1k/day) and a free access route was implemented to allow users to run feasibility and plot projects. Pilot and feasibility studies are particularly important for DNP MAS NMR because the sensitivity gain provided by this method crucially depend on the optimization of the sample preparation. The percentage of access time through the costed route has increased from initially 2% to 31% in the second year, but this is not enough to operate the Facility sustainably after the end of August 2018 when current EPSRC funding for the free access route will run out. A case is made to extent the EPSRC contribution to the operating costs for another two years, so that equipment sharing can be maximised by increasing the user group using targeted actions and increasing the conversion of feasibility studies into grant proposals submitted to RCUK.

Solid-state magic angle spinning (MAS) NMR spectroscopy in combination with Dynamic Nuclear Polarization (DNP) has recently emerged as a powerful technique for characterizing the structure and dynamics of amorphous or heterogeneous materials and biological systems at the atomic level. The large sensitivity gain relative to conventional solid-state NMR allows experiments to be performed that are currently not feasible because of time constraints. Examples include the detection of insensitive isotopes at low natural abundance (such as 17O) and correlation experiments between pairs of nuclei (such as 13C or 15N). In addition NMR signals from molecules absorbed on surfaces or from proteins in intact cells can be detected for the first time. DNP is based on the transfer of the significantly larger electron spin polarisation from paramagnetic centres to the nuclear spins of interest using a strong microwave field. A critical step for success is the optimal sample preparation in which the material under investigation is mixed with organic radicals. The huge potential of DNP MAS NMR has led to a recent surge of research activity aimed at gaining a more detailed understanding of the underpinning physics of DNP and optimizing experimental protocols for sample preparation.

Without novel developments in techniques for structure characterization such as solid-state NMR the molecular sciences would not be able to achieve their potential impact on the wealth and health of the UK. Over the last decades the impact of solid-state NMR measurements on diverse areas of science, technology and industry has been considerable. For example, the method has provided crucial insight into the role of defects in electrode materials in cycling of rechargeable batteries, into the effect of polymorphism on pharmaceutical formulations and into the structure of ion channels in cell membranes targeted by new drugs. However, lack of sensitivity means that solid-state NMR is often unfeasible for real systems where the active component is present in small concentrations, such as catalysts supported on surfaces, drug molecules in pharmaceutical formulations or particular proteins in whole cells. Nevertheless, the atomic-level structural characterization even for amorphous or heterogeneous systems provided by solid-state NMR is a pre-requisite for intelligent molecular design of new materials or understanding the structural biology behind new therapeutic treatments. The new DNP MAS NMR technology has the potential to overcome the sensitivity issue in many NMR application by providing signal enhancements by a factor ~100 and more, corresponding to a 10,000-fold decrease in the required experiment time. This represents a paradigm shift in the capability of solid-state NMR which opens up significant possibilities for new applications. Thus, the impact of DNP on the broad range of science already underpinned by solid-state NMR will be substantial.

At Nottingham the DNP MAS NMR instrument will continue to provide a unique and novel capability adding value to research in a range of RCUK-funded high-impact priority areas, including advanced manufacturing, sustainable processing, energy, drug discovery and biomedical imaging. Potential developments in these areas extend beyond the underlying science and encompass the economic well-being of the UK, the quality of life of its citizens or solutions to global problems, such as climate change. For example, insight from DNP will help design novel catalysts which support new processing technologies, improved porous materials for CO2 sequestration or H2 storage or new antimicrobial therapies.

At the time of its implementation some 40 researchers institutions expressed an interest in using the DNP MAS NMR Facility and a large proportion have already used the free access route to evaluate the benefits of the technique. The many novel applications and interesting projects already carried out (see Case for Support) and initially proposed in their Letters of Support reflect the unique versatility of solid-state NMR in the UK and the potential impact of DNP on this portfolio. Many of the advances envisaged through the application of DNP are aimed exactly at the big questions behind the EPSRC's research themes and grand challenges (e.g. energy storage and catalysis).

An extension of the free access route will lead to an increase of the current user pool and consequently to the development of a portfolio of grants that will provide sustained funding for paid access and coverage of the operating costs. Extrapolating from the development over the last two year we anticipate that the impact of an extension of the free access scheme will lead to about 75% coverage of the operating costs through paid access in contrast to the currently 31% coverage. This significant increase will be based on targeted advertising of the Facility to potential user groups that are currently unrepresented and providing more time for complete pilot studies of the existing user groups so full grant proposal can be submitted to EPSRC.