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Metabolism is a fundamental process that underlies human health and diseases. Nuclear magnetic resonance (NMR) techniques offer a powerful approach to identify metabolic processes and track the flux of metabolites at the molecular level in living systems. An in vitro study through in-cell NMR tracks metabolites in real time and investigates protein structures and dynamics in a state close to their most natural environment. This technique characterizes metabolites and proteins involved in metabolic pathways in prokaryotic and eukaryotic cells. In vivo magnetic resonance spectroscopy (MRS) enables whole-organism metabolic monitoring by visualizing the spatial distribution of metabolites and targeted proteins. One limitation of these NMR techniques is the sensitivity, for which a possible improved approach is through isotopic enrichment or hyperpolarization methods, including dynamic nuclear polarization (DNP) and parahydrogen-induced polarization (PHIP). DNP involves the transfer of high polarization from electronic spins of radicals to surrounding nuclear spins for signal enhancements, allowing the detection of low-abundance metabolites and real-time monitoring of metabolic activities. PHIP enables the transfer of nuclear spin polarization from parahydrogen to other nuclei for signal enhancements, particularly in proton NMR, and has been applied in studies of enzymatic reactions and cell signaling. This review provides an overview of in-cell NMR, in vivo MRS, and hyperpolarization techniques, highlighting their applications in metabolic studies and discussing challenges and future perspectives., (© 2024. The Author(s).)

In NMR-based untargeted metabolomic studies, 1 H NMR spectra are usually divided into equal bins/buckets to diminish the effects of peak shift caused by sample status or instrument instability, and to reduce the number of variables used as input for the multivariate statistical analysis. It was noticed that the peaks near bin boundaries may cause significant changes in integral values of adjacent bins, and the weaker peak may be obscured if it is allocated in the same bin with intense peaks. Several efforts have been taken to improve the performance of binning. Here we propose an alternative method, named P-Bin, based on the combination of the classic peak-picking and binning procedures. The location of each peak defined by peak-picking is used as the center of the individual bin. P-Bin is expected to keep all spectral information associated with the peaks and significantly reduce the data size as the spectral regions without peaks are not considered. In addition, both peak-picking and binning are routine procedures, making P-Bin easy to be implemented. To verify the performance, two sets of experimental data from human plasma and Ganoderma lucidum (G. lucidum) extracts were processed using the conventional binning method and the proposed method, before the principal component analysis (PCA) and the orthogonal projection to latent structures discriminant analysis (OPLS-DA). The results indicate that the proposed method has improved both the clustering performance of PCA score plots and the interpretability of OPLS-DA loading plots, and P-Bin could be an improved version of data preparation for metabonomic study., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

In-cell NMR spectroscopy is an effective tool for observing proteins at atomic resolution in their native cellular environment. However, its utility is limited by its low sensitivity and the extensive line broadening caused by nonspecific interactions in the cells, which is even more pronounced in human cells due to the difficulty of overexpressing or delivering high concentrations of isotopically labeled proteins. Here, we present a high-sensitivity tag (wPSP-6F) containing two trifluoromethyl groups that can efficiently label globular proteins with molecular weights in the 6-40 kDa range under mild conditions. This tag allowed us to detect globular proteins in human cells at concentrations as low as 1.0 μM, which would not have been achievable with 15 N or 3-fluorotyrosine labeling. Moreover, we detected conformational changes and interactions of proteins in the cellular environment. The new sensitive 19 F NMR tag may significantly expand the scope of protein NMR in human cells., (© 2023 Wiley-VCH GmbH.)

A novel approach, concentration-ordered NMR spectroscopy (CORDY), is being proposed based on the principle that the ratio of the NMR peak area to its associated number of spins is proportional to the concentration of the assigned compound. Besides, prior information of chemical shift distribution and line shape characteristics of different chemical groups is utilized to shrink the solution space. CORDY generates a pseudo-two-dimensional NMR spectrum with chemical shifts in one axis and concentrations in the other, resulting in both separation and quantitation of components in complex samples. The method was validated by application to three samples-a model mixture containing six amino acids, sugar-free Red Bull, and human urine. It was demonstrated that CORDY could successfully separate the components with up to 2 orders of magnitude in the concentration dimension for the samples used in the current study. In addition, a combination of CORDY and DOSY (CORDY-DOSY) has been found to be more efficient in resolving the molecules with similar concentrations or self-diffusion coefficients.

To realize sensing and labeling biomarkers is quite challenging in terms of designing multimodal imaging probes. In this study, we developed a novel β‐galactosidase (β‐gal) activated bimodal imaging probe that combines near‐infrared (NIR) fluorescence and magnetic resonance imaging (MRI) to enable real‐time visualization of activity in living organisms. Upon β‐gal activation, Gal‐Cy‐Gd‐1 exhibits a remarkable 42‐fold increase in NIR fluorescence intensity at 717 nm, allowing covalent labeling of adjacent target enzymes or proteins and avoiding molecular escape to promote probe accumulation at the tumor site. This fluorescence reaction enhances the longitudinal relaxivity by approximately 1.9 times, facilitating high‐resolution MRI. The unique features of Gal‐Cy‐Gd‐1 enable real‐time and precise visualization of β‐gal activity in live tumor cells and mice. The probe's utilization aids in identifying in situ ovarian tumors, offering valuable assistance in the precise removal of tumor tissue during surgical procedures in mice. The fusion of NIR fluorescence and MRI activation through self‐immobilizing target enzymes or proteins provides a robust approach for visualizing β‐gal activity. Moreover, this approach sets the groundwork for developing other activatable bimodal probes, allowing real‐time in vivo imaging of enzyme activity and localization. [ABSTRACT FROM AUTHOR]

Keywords: 19F MRI; Biosensors; Fluorescence Imaging; Hypoxia; Nitroreductase EN 19F MRI Biosensors Fluorescence Imaging Hypoxia Nitroreductase 1 1 1 12/07/22 20221212 NES 221212 B Eine bimodale Bildgebungssonde b FCy7-NO SB 2 sb wurde eingesetzt, um die bei Lungenkrebs überexprimierte Nitroreduktase in vivo abzubilden, wie Xin Zhou et al. in ihrem Forschungsartikel berichten (e202213495). 19F MRI, Biosensors, Fluorescence Imaging, Hypoxia, Nitroreductase Die Integration zweier komplementärer Bildgebungstechnologien in FCy7-NO SB 2 sb ermöglicht einen empfindlichen Nachweis von Nitroreduktase in einem breiten Konzentrationsbereich ohne Gewebetiefenbegrenzung. [Extracted from the article]