Extracellular matrixes (ECMs), such as the cell walls and biofilms, are important for supporting cell integrity and function and regulating intercellular communication. These biomaterials are also of significant interest to the production of biofuels and the development of antimicrobial treatment. Solid-state nuclear magnetic resonance (ssNMR) and magic-angle spinning-dynamic nuclear polarization (MAS-DNP) are uniquely powerful for understanding the conformational structure, dynamical characteristics, and supramolecular assemblies of carbohydrates and other biomolecules in ECMs. This review highlights the recent high-resolution investigations of intact ECMs and native cells in many organisms spanning across plants, bacteria, fungi, and algae. We spotlight the structural principles identified in ECMs, discuss the current technical limitation and underexplored biochemical topics, and point out the promising opportunities enabled by the recent advances of the rapidly evolving ssNMR technology.

We report 125 Te NMR measurements of the topological quantum material ZrTe5. Spin-lattice relaxation results, well-explained by a theoretical model of Dirac electron systems, reveal that the topological characteristic of ZrTe5 is T -dependent, changing from weak topological insulator to strong topological insulator as temperature increases. Electronic structure calculations confirm this ordering, the reverse of what has been proposed. NMR results demonstrate a gapless Dirac semimetal state occurring at a Lifshitz transition temperature, Tc = 85 K in our crystals. We demonstrate that the changes in NMR shift at Tc also provide direct evidence of band inversion when the topological phase transition occurs.

We present a 63Cu and 65Cu NMR study of Cu12Sb4S13, the basis for tetrahedrite thermoelectric materials. In addition to electronic changes observed at the T c = 88 K metal–insulator transition, we find that locally there are significant structural changes occurring as the temperature extends above T c, which we associate with Cu atom displacements away from symmetry positions. Spin-lattice relaxation rates (1/T 1) are dominated by a quadrupolar process indicating anharmonic vibrational dynamics both above and below T c. We used a quasiharmonic approximation for localized anharmonic oscillators to analyze the impact of Cu rattling. The results demonstrate that Cu-atom rattling dynamics extends unimpeded in the distorted structural configuration below T c and provide a direct measure of the anharmonic potential well.

To investigate the electronic behavior and magnetic properties of NbFeSb, we have performed 93Nb NMR, specific heat and magnetic measurements on NbFeSb samples heat treated at high temperatures. Magnetic measurements combined with an observed Schottky anomaly and changes in the NMR line width indicate the presence of a 0.2% concentrated native magnetic defect in stoichiometric NbFeSb samples. The origin of these native defects is believed to be due to Fe antisites on Nb sites. In addition, NMR shift and spin-lattice relaxation results below 200 K reveal a Korringa-like response indicating heavily-doped p-type behavior due to native defects. Above 280 K, this converts to an activated behavior, indicating the presence of an impurity band, empty at low temperatures, which is located around 0.03 eV above the valence band maximum.