A magnetic resonance (MR)-fluorescent dual-mode imaging probe was prepared by conjugating guaiazulene to Gd-DOTA, and used to label human mesenchymal stem cells (hMSCs) via electroporation. The probe self-assembled into nanoclusters in the cytoplasm, resulting in a significant reduction in T₂-weighted signal intensity that persisted up to 7 days. The fluorescence signal of the probe was observed at 498 nm, and the labelled hMSCs emitted a green fluorescence. The MR-fluorescent dual-mode imaging probe can potentially be used for stem cell tracking in vivo.

The Haller relationship was applied to estimate the nematic order parameter S from ¹H NMR spectra of fully protonated liquid crystals aligned in the magnetic field. The NMR line shapes were approximated as doublets of very broad peaks. Both the temperature-dependent doublet Splitting and the full width at half maximum of the whole spectra were used for Haller extrapolation. The order parameters obtained with the proposed approach for 4-cyano-4'-pentylbiphenyl (5CB) and the nematic mixture E7 were found to be in good agreement with previously reports.

Nuclear receptor binding SET domain protein 1 (NSD1), which is a family member of histone methyltransferases, functions to methylate histone H3 on lysine 36 (H3K36). NSD1-related abnormalities are the major cause of Sotos syndrome, and also known to be associated with other human diseases. Inhibitors targeting histone methyltransferases DOT1L and EZH2 have been reported recently. However, no chemical probes targeting NSD1 have been found so far. Here, we identified three hits targeting the NSD1 SET domain using ligand-observed nuclear magnetic resonance (NMR) fragment-based screening. The binding affinities of the hit compounds to the NSD1 SET domain were determined by dose-dependent chemical shift perturbation analysis. Furthermore, the potential binding modes of the hit compounds to NSD1 were obtained by molecular docking. The hit compound 1 was found to bind to the binding pocket of S-adenosylmethionine (SAM), an endogenous ligand of the protein, in the NSD1 SET domain. The study provided valuable information for further structure-guided hit-to-lead evolution towards the potent and specific inhibitors of the NSD1 SET domain.

Ultraviolet-visible and nuclear magnetic resonance (NMR) spectroscopy was used to investigate the effects of pH, solvent and temperature on the tautomeric equilibrium of selaginellins from Selaginella. The results demonstrated that the tautomerism of selaginellins could be catalyzed by acid, base and protic solvent. Variable-temperature ¹H NMR experiments demonstrated that the tautomerism was interrupted when the temperature fell below 233 K.

PhoB is a response regulator of the PhoR/PhoB two-component system (TCS) in Escherichia Coli, which is involved in environmental phosphate regulation. PhoB activation is known to be mediated by Mg²⁺ coordination and phosphorylation of the conserved D53 residue, but the exact mechanism remains to be elucidated. It has been proposed that minor active conformations of the response regulator may preexist in its apo state and be related to the activation. However, such minor states are instable and difficult to observe. In this work, ¹H-¹⁵N HSQC and ¹⁹F NMR experiments were performed on a monomeric mutant PhoB_N^F20D. It was observed that the apo PhoB_N^F20D had a pre-active conformation, which could be partially stabilized by the phosphoryl group analog BeF₃^-without the presence of Mg²⁺. Addition of Mg²⁺ shifted the equilibrium towards the active form. Furthermore, the exchange between the inactive and active conformations were confirmed by the CPMG (Carr-Purcell-Meiboom-Gill) relaxation dispersion experiments. It is concluded that the apo PhoB_N^F20D have both inactive and active conformations, and the pre-active conformation can be stabilized by BeF₃^-.

The biological effects of ionizing radiation on organisms have emerged as a hot topic for research. In this study, the changes of metabolic profile in the kidney tissues extracts from C57BL/6J mice with or without exposing to whole body gamma or proton radiation were investigated with the liquid state proton nuclear magnetic resonance (¹H NMR)-based metabolomics approach. The results demonstrated that the exposed group had significantly different kidney metabolic profiles from the non-exposed group, involving mainly six metabolites, including 2-aminobutyrate, 3-hydroxybutyrate, homoserine, 1,3-diaminopropane, β-alanine and ascorbate. These metabolites could be used as potential biomarkers for the biological effects of high-dose ionizing radiation on kidney metabolism.

Gegen Qinlian Decoction (GQD) is a commonly used traditional Chinese medicine formula for treating type 2 diabetes mellitus and insulin resistance (IR). The effects of GQD treatment on intestinal flora and its metabolism, however, are yet to be understood. In this study, the effects of GQD treatment on the fecal metabonome of high fructose-induced IR rats were investigated with a ¹H NMR-based approach. The IR model was established by feeding the rats with 10% fructose solution for 8 consecutive weeks. The animals in the GQD treatment group were gavaged with GQD daily (18.2 g/kg/day) from the 5th to 8th week. Compared with control group, The IR rats showed significantly increases in water/food intakes, body weight and IR index at the ends of the 4th and 8th week. The fasted plasma glucose (FPG) level of the IR rats increased by the end of the 8th week. The GQD treatment lowered the IR index and normalized fecal metabonome by increasing the levels of propionate, acetate, succinate, taurine and glycerol, while decreasing the levels of n-butyrate, alanine and glutamate. These results indicated that the GQD treatment induced positive changes in amino acid metabolism, fatty acid oxidation and gut microbiota metabolism in the IR rats.

Non-invasive and quantifiable diagnosis of Parkinson's disease (PD) is an ongoing challenge for researchers. In this study, we compared two different chemical exchange saturation transfer (CEST) imaging quantification metrics in substantia nigra (SN), cortex and hippocampus of acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mice at three different time points including before MPTP administration, and the 3^rd and 10^th day after MPTP administration. Area of amine (Area_amine), magnetization transfer ratio yielding R_ex (MTR_rex) and apparent exchange-dependent relaxation (AREX) in SN derived from 5-pool Lorentzian fitting and inverse Z-spectrum analysis showed a statistically significant decrease after successful modeling, while there were no significant alterations in T₁, T₂, and magnetization transfer ratio based on asymmetry analysis (MTR_asym). The results suggested that the former quantification is superior to that based on Z-spectrum asymmetry in vivo due to the exclusion of direct saturation (DS) and magnetic transfer (MT) effects and may reflect the destroying SN of PD.

Electron paramagnetic resonance (EPR) with the use of exogenous spin probes is an indispensable tool to measure pH in vitro and in vivo. Monophosphonated tetrathiatriarylmethyl (p₁TAM) radicals are so far the most promising EPR probes for pH measurement. However, their biological applications were limited by extremely low efficiency in synthesis and potential albumin binding, such that they could not be administered systematically. In the present work, an efficient procedure for p₁TAM synthesis was reported, with a total yield of 25% from the corresponding triarylmethanol (compared to 1.6% with the commonly used procedure). Further PEGylation prevented the interaction between p₁TAM and albumin. The EPR spectra of nondeuterated (POP) and deuterated (dPOP) PEGylated derivatives of p₁TAM were also recorded at different pH values. The two probes had similar pH sensitivities with pKa values of 6.80 and 6.79, respectively. POP had a much more complex EPR spectrum than dPOP, with the latter always exhibiting simple EPR doublet signals regardless of the pH. These results suggested that dPOP is more advantageous for pH measurement, relative to POP and p₁TAM. Moreover, dPOP was shown to have excellent biological stability and high O2 sensitivity, and thus might have the potential to be used as the probe for simultaneous pH and O2 measurements in biological system.

As revealed by ¹H NMR experiments, the critical micelle concentration (CMC) of a surfactant in the aqueous solution decreases when a surfactant of different type is mixed in, a phenomenon that has been explained by the adsorption equilibrium theory. It has also been observed that the extents of mixing-induced reduction in CMC values differ among different surfactant types, depending on the interactions (absorption or repulsion) between the adsorbed surfactant molecules and the adsorption mono-layer. The results of ¹H NMR experiments provided a clear picture for the so-called "synergistic effect", and thus might be used to guide the optimization of surfactant mixture formula to achieve desired performance.

A software package, MRISim, for virtual magnetic resonance imaging (MRI) data acquisition and image reconstruction was developed based on numerical simulation techniques. Virtual MRI data acquisition could be achieved through physical-mathematical modeling of the equipment and samples (i.e., phantom or human body). Image reconstruction of the virtual data was performed in the same manner as that in a real desktop MRI scanner. The software could also be applied for visualization of the features and causes of a variety of MRI artifacts, with the acquisition and processing parameters in the real experiments. MRISim was demonstrated as an efficient and reliable tool to conduct virtual MRI experiments, avoiding high expense of MRI training on real instruments.

The ¹⁹F nucleus has a high gyromagnetic ratio that is comparable to that of proton. Due to its high sensitivity and low background in the biological systems, ¹⁹F labeling has emerged as an attractive approach in biological solid-state NMR studies. In this review, we summarized the widely used ¹⁹F-labeling strategies, ¹⁹F solid-state NMR spectroscopy techniques to probe membrane protein interactions, and the recent applications of ¹⁹F solid-state NMR in characterizing of membrane proteins. The limitations of ¹⁹F solid-state NMR were also highlighted.