Metabolic fluorine labeling and hotspot imaging of dynamic gut microbiota in mice

Abstract

Real-time localization and microbial activity information of indigenous gut microbiota over an extended period of time remains a challenge with existing visualizing methods. Here, we report a metabolic fluorine labeling (MEFLA)–based strategy for monitoring the dynamic gut microbiota via 19 F magnetic resonance imaging ( 19 F MRI). In situ labeling of different microbiota subgroups is achieved by using a panel of peptidoglycan-targeting MEFLA probes containing 19 F atoms of different chemical shifts, and subsequent real-time in vivo imaging is accomplished by multiplexed hotspot 19 F MRI with high sensitivity and unlimited penetration. Using this method, we realize extended visualization (>24 hours) of native gut microbes located at different intestinal sections and semiquantitative analysis of their metabolic dynamics modulated by various conditions, such as the host death and different β-lactam antibiotics. Our strategy holds great potential for noninvasive and real-time assessing of the metabolic activities and locations of the highly dynamic gut microbiota.

Bacteria‐Based Living Probes: Preparation and the Applications in Bioimaging and Diagnosis

“…Gao et al used 19 F metabolism to label the gut microbiota and realized real-time 19 F MRI in vivo imaging and the extended visualization of gut microbes in different intestinal segments. [168] Liu et al labeled B. fragilis with 64 Cu and fluorescent dye through metabolic oligosaccharide engineering and biorthogonal click chemistry, and Reproduced with permission. [165] Copyright 2021, American Chemical Society.…”

“…Gao et al used 19 F metabolism to label the gut microbiota and realized real‐time 19 F MRI in vivo imaging and the extended visualization of gut microbes in different intestinal segments. [ 168 ] Liu et al labeled B. fragilis with 64 Cu and fluorescent dye through metabolic oligosaccharide engineering and biorthogonal click chemistry, and successfully detected the in vivo behavior of B. fragilis after transplantation by PET imaging. [ 133 ] These strategies provide a valuable basis for in situ imaging and real‐time monitoring of the gut microbiota, representing a favorable reference for the development of novel bacteria‐based living probes for future clinical applications.…”

Glycan Metabolic Fluorine Labeling for In Vivo Visualization of Tumor Cells and In Situ Assessment of Glycosylation Variations

“…On the basis of these considerations, we envisioned the direct incorporation of 19 F into unnatural sugars, which takes advantage of 19 F's chemical inertness (in certain organic functional groups such as -CF 3 ) and negligible biological background, could provide a potential solution to overcome the limitations of those approaches involving two-step labeling. As a proof of concept for this strategy, i.e., glycan metabolic fluorine labeling (MEFLA), [45] we designed and synthesized two 19 F-containing monosaccharide-based probes (Ac 4 ManNTfe and Ac 4 GalNTfa, see Scheme 1 for their chemical structures), which could be clearly distinguished by 19 F NMR/MRI due to their significantly different 19 F chemical shifts. These two probes were expected to be selectively taken up by tumor cells and subsequently incorporated into their surface glycans, which enables efficient and specific 19 F labeling and permits in vivo tracking of tumor cells and in situ assessment of glycosylation changes.…”

Paramagnetic MgF2 Nanocrystals for 19F Magnetic Resonance Imaging

“…9 These encouraging results, even in live animal models, suggest that MgF 2 NCs might be used for 19 F magnetic resonance imaging (MRI) applications, as recently demonstrated in several animal models for other types of nanofluorides (CaF 2 , SrF 2 , and BaF 2 ). 10−12 Formulations developed for 19 F-MRI are of diverse types, ranging from emulsified perfluorocarbon materials 13−16 to ionic liquids, 17 fluorinated ligands, 18,19 polymers, 20,21 supramolecular assemblies, 22 fluorine-modified nanoclusters, 23 fluorine-modified gold nanoparticles, 24 fluorinated D-amino acids, 25 and more. 26 Although they differ one from the other, the commonality of these molecular architectures is that they all provide a well-defined, high-resolution, liquid-state 19 F-NMR spectrum while being dissolved in an aqueous solution.…”

“…Formulations developed for 19 F-MRI are of diverse types, ranging from emulsified perfluorocarbon materials − to ionic liquids, fluorinated ligands, , polymers, , supramolecular assemblies, fluorine-modified nanoclusters, fluorine-modified gold nanoparticles, fluorinated d -amino acids, and more . Although they differ one from the other, the commonality of these molecular architectures is that they all provide a well-defined, high-resolution, liquid-state 19 F-NMR spectrum while being dissolved in an aqueous solution.…”