Advances in High-Field DNP Methods

Abstract

Magic-angle sample spinning NMR (MAS NMR) spectroscopy is a powerful tool for studying atomic resolution structure and dynamics of insoluble and/or non-crystalline molecular systems such as membrane proteins and amyloid fibrils, but suffers from its low sensitivity. Dynamic nuclear polarization (DNP) is an emerging technique that enhances the NMR sensitivity by transferring large electron spin polarization to the nuclei of interest through a high-power microwave irradiation, enabling aforementioned molecular structural and dynamical studies at unprecedented signal receptivity. Despite the remarkable advances achieved in the past two decades, the current high-field DNP-MAS NMR method still endures a number of limitations and difficulties. This thus calls for a further sophistication of the method, especially for implementing it at very high-field conditions, which is crucial for high-resolution studies targeting systems with ever-increasing size and complexity. This chapter aims at providing an overview on the contemporary high-field DNP instruments and methods. Together with the current success, the authors highlight the remaining technical issues and limitations to give a baseline for the future development and innovation. Detailed description of the instruments as well as the DNP samples should provide a useful piece of information for managers of DNP spectrometers for avoiding/solving day-to-day technical problems, as well as for users to improve their sample setups, or to design a new research plan.