Spatial molecular-dynamically ordered NMR spectroscopy of intact bodies and heterogeneous systems

Kengo Ito,Jun Kikuchi,Yuuri Tsuboi

doi:10.1038/s42004-020-0330-1

Abstract

Noninvasive evaluation of the spatial distribution of chemical composition and diffusion behavior of materials is becoming possible by advanced nuclear magnetic resonance (NMR) pulse sequence editing. However, there is room for improvement in the spectral resolution and analytical method for application to heterogeneous samples. Here, we develop applications for comprehensively evaluating compounds and their dynamics in intact bodies and heterogeneous systems from NMR data, including spatial z-position, chemical shift, and diffusion or relaxation. This experiment is collectively named spatial molecular-dynamically ordered spectroscopy (SMOOSY). Pseudo-three-dimensional (3D) SMOOSY spectra of an intact shrimp and two heterogeneous systems are recorded to evaluate this methodology. Information about dynamics is mapped onto two-dimensional (2D) chemical shift imaging spectra using a pseudo-spectral imaging method with a processing tool named SMOOSY processor. Pseudo-2D SMOOSY spectral images can non-invasively assess the different dynamics of the compounds at each spatial z-position of the shrimp’s body and two heterogeneous systems.

Highlights

Noninvasive evaluation of the spatial distribution of chemical composition and diffusion behavior of materials is becoming possible by advanced nuclear magnetic resonance (NMR) pulse sequence editing
A pulse sequence combining chemical shift imaging (CSI) and Diffusion-ordered spectroscopy (DOSY) has already been reported, but in this study, a highly resolved spectrum was obtained using HR-magic angle spinning (MAS), and the pseudo-2D spectral imaging method has improved the performance of compound diffusion evaluation in the spatial z-position
If the diffusion encoding is changed to T1 or T2, the magnetic relaxation phenomena of the compounds in the spatial z-position can be analyzed, which is the first report at this time

Summary

Introduction

Noninvasive evaluation of the spatial distribution of chemical composition and diffusion behavior of materials is becoming possible by advanced nuclear magnetic resonance (NMR) pulse sequence editing. We develop applications for comprehensively evaluating compounds and their dynamics in intact bodies and heterogeneous systems from NMR data, including spatial z-position, chemical shift, and diffusion or relaxation This experiment is collectively named spatial molecular-dynamically ordered spectroscopy (SMOOSY). MRI and MRS have made a major contribution in the field of medicine because they can be used for the noninvasive evaluation of spatial 1H density, diffusion or relaxation, and chemical shift in biological and other samples[10,11] In this background, the Nobel Prize in Chemistry 1991 was awarded to Richard R. Diffusion-ordered spectroscopy (DOSY) is a pseudo-two-dimensional (2D) NMR technique that diffusion coefficients can be extracted from pulsed-field gradient-attenuation profile collected in DOSY experiments This technique is useful for mixture analysis because it allows the separation of signals of compounds with different molecular weights[17].

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Results

Conclusion