From overlap to resolution: Cellular solid-state NMR at ultrahigh-field 1.5 GHz demonstrated on fungal cell walls

Ultrahigh-field solid-state NMR in the GHz frequency range has opened new frontiers for probing complex, heterogeneous biological systems with unprecedented spectral resolution. Here, we demonstrate the advantages of a 1.5 GHz (35.2 T) NMR spectrometer for cellular solid-state NMR by quantitatively assessing ¹³C linewidth improvements in intact, living fungal cells of Aspergillus fumigatus. High-quality 2D¹³C-¹³C correlation spectra were acquired within 2-5 h, showing consistent linewidth narrowing of 0.05-0.15 ppm under idealized conditions and exceeding 0.2 ppm under realistic, power-limited running time constraints relative to 800 MHz. The resolution gains are especially pronounced for overlapped and inhomogeneously broadened resonances in multidimensional correlation experiments and are most significant in power-demanding recoupling experiments where acquisition times must be shortened. These improvements enable the resolution of extensive previously inaccessible spectral multiplicity and structural polymorphism in cellular carbohydrates such as chitin and α-1,3-glucan, while substantially reducing experimental time relative to lower-field approaches. These results illustrate the potential advantages of ultrahigh-field solid-state NMR for improving spectral resolution in complex cellular materials and emphasize the importance of continued development of computational and analytical approaches to effectively interpret the increasingly information-rich spectra obtained at these fields.