Tailoring the Performance of 19F-Labeled Probes via Dynamic Covalent Chemistry for Improved Chiral Discrimination.

This work presents a novel strategy for postmodifying probes using dynamic covalent chemistry. Leveraging reversible interactions between boronic acid and diols, we obtained a panel of 19F-labeled probes with distinct resolving abilities. This approach enables rapid identification of probes with satisfactory performance, streamlining synthesis, and enhancing efficiency in chiral analysis. Our findings demonstrate an exceptional ability to differentiate compounds with distal chirality and challenging aliphatic amines. The postmodified probes also exhibit accuracy and reliability in determining enantiomeric excess, promising advancements in enantio-analysis techniques and chiral discrimination.

Detection and Identification of Nitrile Compounds via Recognition-Enabled Chromatographic 19F NMR.

The surge in applications of nitrile compounds across diverse fields, such as pharmaceuticals, agrochemicals, dyes, and functional materials, necessitates the development of rapid and efficient detection and identification methods. In this study, we introduce a chemosensing strategy employing a novel 19F-labeled probe, facilitating swift and accurate analysis of a broad spectrum of nitrile-containing analytes. This approach leverages the reversible interaction between the 19F-labeled probe and the analytes to produce chromatogram-like outputs, ensuring the precise identification of various pharmaceuticals and pesticides within complex matrices. Additionally, this dynamic system offers a versatile platform to investigate through-space 19F-19F interactions, showcasing its potential for future applications in mechanistic studies.

NMR-Based Chiral Discrimination of Bulky Amines with a 19F-Tagged NNO Pincer Complex.

Within pharmaceutical research, ensuring the enantiomeric purity of chiral compounds is critical. Specifically, chiral amines are a crucial category of compounds, due to their extensive therapeutic uses. However, the enantiomeric analysis of these compounds, particularly those with significant steric hindrance, remains a challenge. To address this issue, our research introduces a novel chiral 19F-tagged NNO palladium pincer probe, strategically engineered with an open binding site to accommodate bulky amines. This probe facilitates the enantiodifferentiation of such amines, as evidenced by the distinct 19F NMR signals generated by the enantiomers. Moreover, our findings highlight the probe's applicability in the chiral discrimination of various psychoactive substances, underscoring its potential for the identification of illegal stimulant use and contributing to forensic investigations.

Mechanisms of synthetic bacterial flora YJ-1 to enhance cucumber resistance under combined phthalate-disease stresses.

Biotic and abiotic stresses have emerged as major constraints to agricultural production, causing irreversible adverse impacts on agricultural production systems and thus posing a threat to food security. In this study, a new strain of Bacillus subtilis DNYB-S1 was isolated from soil contaminated with Fusarium wilt. It was found that artificially synthetic flora (YJ-1) [Enterobacter sp. DNB-S2 and Rhodococcus pyridinovorans DNHP-S2, DNYB-S1] could effectively mitigate both biotic (Fusarium wilt) and abiotic (phthalates) sources of stresses, with the inhibition rate of YJ-1 resistant to wilt being 71.25% and synergistic degradation of 500 mg/L PAEs was 91.23%. The adaptive difference of YJ-1 was 0.59 and the ecological niche overlap value was -0.05 as determined by Lotka-Volterra modeling. These results indicate that YJ-1 has good ecological stability. The major degradation intermediates included 2-ethylhexyl benzoate (EHBA), phthalic acid (PA), diisobutyl phthalate (DIBP), and butyl benzoate, suggesting that YJ-1 can provide a more efficient pathway for PAEs degradation. In addition, there was metabolic mutualism among the strains that will selectively utilize the provided carbon source (some metabolites of PAEs) for growth. The pot experiment showed that YJ-1 with cucumber reduced the incidence of cucumber wilt by 45.31%. YJ-1 could reduce the concentration of PAEs (DBP: DEHP = 1:1) in soil species from 30 mg/kg to 4.26 mg/kg within 35 d, with a degradation efficiency of 85.81%. Meanwhile, the concentration of PAEs in cucumber was reduced to 0.01 mg/kg, indicating that YJ-1 is directly involved in the degradation of soil PAEs and the enhancement of plant immunity. In conclusion, this study provides a new perspective for the development of customized microbiomes for phytoremediation under combined biotic-abiotic stresses in agricultural production processes.

Improving the Sensitivity of Enantioanalysis with Densely Fluorinated NMR Probes.

Nuclear magnetic resonance (NMR) spectroscopy has long been utilized as a classic method for chiral discrimination of enantiomers. However, its sensitivity limitations have hindered the detection of analytes at low concentrations. In this study, we present our efforts to overcome this challenge by employing chiral NMR probes that are labeled with a significant number of chemically equivalent 19F atoms. Specifically, we have designed and synthesized three chiral palladium pincer complexes, all of which are labeled with nonafluoro-tert-butoxy groups to enhance detectability. The recognition of enantiomers with the probe induces distinct changes in microenvironments, resulting in differential perturbations on the chemical shift of the 19F atoms in proximity. This method is applicable to the enantiodifferentiation of various amines, amino alcohols, and amino acid esters. The abundance of 19F atoms enables the detection of chiral analytes at low concentrations, which is otherwise challenging to achieve through traditional 1H NMR-based analysis. Two of the probes are constructed with asymmetric pincer ligands with structurally varied sidearms, allowing for facile manipulation of the chiral binding pocket. The C2 symmetrical probe possesses 36 equivalent 19F atoms, enabling the determination of enantiocomposition of samples with concentrations in the low micromolar range.

Metal-Free C-H Functionalization via Diaryliodonium Salts with a Chemically Robust Dummy Ligand.

A two-step strategy for the transition-metal-free C-H functionalization of arenes using unsymmetrical iodonium salts as versatile synthetic linchpins is presented. The key to the success of this strategy is the identification of the 3,5-dimethyl-4-isoxazolyl (DMIX) group as a superior dummy ligand, which enables not only site-selective C-H functionalization to afford unsymmetrical iodonium salts, but also highly selective aryl transfer during the subsequent metal-free coupling reaction. Both electron-rich and moderately electron-deficient arenes can be converted into the iodonium salts through C-H functionalization, allowing for diverse structural elaboration by metal-free C-N, C-C, C-S, and C-O coupling.

Regulation of Pyruvate Formate Lyase-Deficient Klebsiella pneumoniae for Efficient 1,3-Propanediol Bioproduction.

Anaerobic growth defect of pyruvate formate lyase (PFL)-deficient Klebsiella pneumoniae limits its industrial application, and the reason for this growth defect was analyzed in this study. The obtained evidences, combined with normal intracellular redox status and no further inhibition by adhE deletion, strongly suggested that growth defect in PFL-deficient K. pneumoniae was probably caused by lack of carbon flux from pyruvate to acetyl-CoA (AcCoA). Correspondingly, the anaerobic growth of PFL-deficient K. pneumoniae was promoted by deletion of pdhR, a negative transcriptional regulator gene for AcCoA generation. Through the regulation of pdhR deletion, the PFL-deficient K. pneumoniae exhibited highly efficient 1,3-propanediol production. Besides, in a 2-L fed-batch fermentation process, the cell growth of PFL-deficient K. pneumoniae strain almost recovered, when compared with that of the normal strain, and the 1,3-propanediol yield increased by 14%, while the byproducts acetate and 2,3-butanediol contents decreased by 29% and 24%, respectively.

miR-322/-503 cluster is expressed in the earliest cardiac progenitor cells and drives cardiomyocyte specification.

Understanding the mechanisms of early cardiac fate determination may lead to better approaches in promoting heart regeneration. We used a mesoderm posterior 1 (Mesp1)-Cre/Rosa26-EYFP reporter system to identify microRNAs (miRNAs) enriched in early cardiac progenitor cells. Most of these miRNA genes bear MESP1-binding sites and active histone signatures. In a calcium transient-based screening assay, we identified miRNAs that may promote the cardiomyocyte program. An X-chromosome miRNA cluster, miR-322/-503, is the most enriched in the Mesp1 lineage and is the most potent in the screening assay. It is specifically expressed in the looping heart. Ectopic miR-322/-503 mimicking the endogenous temporal patterns specifically drives a cardiomyocyte program while inhibiting neural lineages, likely by targeting the RNA-binding protein CUG-binding protein Elav-like family member 1 (Celf1). Thus, early miRNAs in lineage-committed cells may play powerful roles in cell-fate determination by cross-suppressing other lineages. miRNAs identified in this study, especially miR-322/-503, are potent regulators of early cardiac fate.

Au/ZnSe-Based Surface Enhanced Infrared Absorption Spectroscopy as a Universal Platform for Bioanalysis.

A versatile and sensitive platform for label-free bioanalysis has been proposed on the basis of attenuated total reflection-surface enhanced infrared absorption spectroscopy (ATR-SEIRAS) using Au/ZnSe as the enhancement substrate that allows a wide spectral range down to 700 cm-1. Au nanoparticles are stably deposited on the surface of a ZnSe prism due to the formation of Au-Se bonds via electroless deposition, and the enhancement factor of the resultant Au/ZnSe substrate is about 2 times larger than that of the commonly used Au/Si substrate. As a demonstration, the Au/ZnSe-based SEIRAS has been applied to obtain abundant structural information in the fingerprint region and quantitative analysis of various biomolecular interactions such as DNA hybridization and immunoreaction without any labeling process.

Water as a Universal Infrared Probe for Bioanalysis in Aqueous Solution by Attenuated Total Reflection-Surface Enhanced Infrared Absorption Spectroscopy.

Monitoring the properties and reactions of biomolecules at their interface has attracted ever-growing interest. Here, we propose an approach of infrared analysis technique that utilizes water molecule as a universal probe for in situ and label free monitoring of interfacial bioevents in aqueous solution with high sensitivity. The strong infrared (IR) signal of O-H stretching vibrations from the repelled water is used to sensitively reveal the kinetics of interfacial bioevents at molecular level based on the steric displacement of water using an attenuated total reflection-surface enhanced infrared absorption spectroscopy. Using interfacial immuno-recognition and DNA hybridization as demonstrations, water IR probe offers 26 and 34 times higher sensitivity and even 200 and 86 times lower detection limit for immunosensing and DNA sensing, respectively, as compared to the traditional IR molecular fingerprints.

Inactivating NADH:quinone oxidoreductases affects the growth and metabolism of Klebsiella pneumoniae.

NADH:quinone oxidoreductases (NQOs) act as the electron entry sites in bacterial respiration and oxidize intracellular NADH that is essential for the synthesis of numerous molecules. Klebsiella pneumoniae contains three NQOs (NDH-1, NDH-2, and NQR). The effects of inactivating these NQOs, separately and together, on cell metabolism were investigated under different culture conditions. Defective growth was evident in NDH-1-NDH-2 double and NDH-1-NDH-2-NQR triple deficient mutants, which was probably due to damage to the respiratory chain. The results also showed that K. pneumoniae can flexibly use NQOs to maintain normal growth in single NQO-deficient mutants. And more interestingly, under aerobic conditions, inactivating NDH-1 resulted in a high intracellular NADH:NAD+ ratio, which was proven to be beneficial for 2,3-butanediol production. Compared with the parent strain, 2,3-butanediol production by the NDH-1-deficient mutant was increased by 46% and 62% in glycerol- and glucose-based media, respectively. Thus, our findings provide a practical strategy for metabolic engineering of respiratory chains to promote the biosynthesis of 2,3-butanediol in K. pneumoniae.

Hot electron of Au nanorods activates the electrocatalysis of hydrogen evolution on MoS2 nanosheets.

Efficient water splitting through electrocatalysis holds great promise for producing hydrogen fuel in modern energy devices. Its real application however suffers from sluggish reaction kinetics due to the lack of high-performance catalysts except noble metals such as platinum. Herein, we report an active system of plasmonic-metal Au nanorods/molybdenum disulfide (MoS2) nanosheets hybrids for the hydrogen evolution reaction (HER). The plasmonic Au-MoS2 hybrids dramatically improve the HER, leading to a ∼3-fold increase of current under excitation of Au localized surface plasmon resonance (LSPR). A turnover of 8.76 s(-1) at 300 mV overpotential is measured under LSPR excitation, which by far exceeds the activity of MoS2 catalysts reported recently. The HER enhancement can be largely attributed to the increase of carrier density in MoS2 induced by the injection of hot electrons of Au nanorods. We demonstrate that the synergistic effect of the hole scavengers can further facilitate electron-hole separation, resulting in a decrease of the overpotential of HER at MoS2 to ∼120 mV. This study highlights how metal LSPR activates the HER and promises novel opportunities for enhancing intrinsic activities of semiconducting materials.

Ultrahigh Enzyme Activity Assembled in Layered Double Hydroxides via Mg(2+)-Allosteric Effector.

It is well-known that some metal ions could be allosteric effectors of allosteric enzymes to activate/inhibit the catalytic activities of enzymes. In nanobiocatalytic systems constructed based on the positive metal ion-induced allosteric effect, the incorporated enzymes will be activated and thus exhibit excellent catalytic performance. Herein, we present an environmentally friendly strategy to construct a novel allosteric effect-based ß-galactosidase/Mg-Al layered double hydroxide (ß-gal/Mg-Al-LDH) nanobiocatalytic system via the delamination-reconstruction method. The intercalated ß-gal in the LDH galleries changes its conformation significantly due to the Mg(2+)-induced allosteric interactions and other weak interactions, which causes the activation of enzymatic activity. The ß-gal/Mg-Al-LDH nanobiocatalytic system shows much higher catalytic activity and affinity toward its substrate and about 30 times higher catalytic reaction velocity than the free ß-gal, which suggests that Mg(2+)-induced allosteric effect plays a vital role in the improvement of enzymatic performance.

Fluorescent Sulfur-Tagged Europium(III) Coordination Polymers for Monitoring Reactive Oxygen Species.

Oxidative stress caused by reactive oxygen species (ROS) is harmful to biological systems and implicated in various diseases. A variety of selective fluorescent probes have been developed for detecting ROS to uncover their biological functions. Generally, the preparation of the fluorescent probes usually undergoes multiple synthetic steps, and the successful fluorescent sensing usually relies on trial-and-error tests. Herein we present a simple way to prepare fluorescent ROS probes that can be used both in biological and environmental systems. The fluorescent europium(III) coordination polymers (CPs) are prepared by simply mixing the precursors [2,2'-thiodiacetic acid and Eu(NO3)3·6H2O] in ethanol. Interestingly, with the increase of reaction temperature, the product undergoes a morphological transformation from microcrystal to nanoparticle while the structure and fluorescent properties retain. The fluorescence of the sulfur-tagged europium(III) CPs can be selectively quenched by ROS, and thus, sensitive and selective monitoring of ROS in aerosols by the microcrystals and in live cells by the nanoparticles has been achieved. The results reveal that the sulfur-tagged europium(III) CPs provide a novel sensor for imaging ROS in biological and environmental systems.

Core-shell Ag@SiO(2) nanoparticles concentrated on a micro/nanofluidic device for surface plasmon resonance-enhanced fluorescent detection of highly reactive oxygen species.

A micro/nanofluidic device integrating a nanochannel in a microfluidic chip was developed for sensitive fluorescent determination of highly reactive oxygen species (hROS) enhanced by surface plasmon resonance-enhanced fluorescence (SPREF). The nanochannel was simply fabricated by polyaniline nanostructures modified on a glass slide. Core-shell Ag@SiO2 nanoparticles were concentrated in front of the nanochannel for fluorescence enhancement based on the SPREF effect. As a demonstration, hROS in the mainstream of cigarette smoke (CS) were detected by the present micro/nanofluidic device. The fluorescent probe for trapping hROS in puffs of CS employed a microcolumn that was loaded with a composite of DNA (conjugated fluorophores, FAM) and Au membrane (coated on cellulose acetate). With a laser-induced fluorescence detection device, hROS was determined on the basis of the amount of FAM groups generated by DNA cleavage. With the optimization of the trapping efficiency, we detected about 4.91 pmol of hROS/puff in the mainstream CS. This micro/nanofluidic-SPREF system promises a simple, rapid, and highly sensitive approach for determination of hROS in CS and other practical systems.

Synthesis of Diaryl Ethers via Hypervalent Iodine-Mediated C-H Functionalization.

A hypervalent iodine-reagent-based C-H functionalization strategy was utilized to synthesize diaryl ethers. This method directly transforms various arenes into their corresponding diaryliodonium salts, followed by a C-O coupling reaction to produce structurally diverse diaryl ethers. The efficacy of this approach in the late-stage structural modifications of complex molecules was demonstrated.

Ring-shaped cavity anchor Pt to derive Pt/WO3-x heterointerfaces for efficient hydrogen evolution in acidic water and seawater.

Developing novelplatinum (Pt)-based hydrogen evolution reaction (HER) catalysts with high activity and stability is significant for the ever-broader applications of hydrogen energy. However, achieving precise modulation of the ultrafine Pt nanoparticles coordination environment in conventional catalysts is challenging. In this work, we developed a unique "ring-shaped cavity induced" strategy to anchor the Ptx through the ring-shaped cavity of polyoxometalates (POMs) Na33H7P8W48O184 (denoted as P8W48). The NayPtx[P8W48O184] (PtxP8W48) was in-situ converted into abundant Pt/WO3-x heterostructure with Pt (∼2 nm) and highly depressed Pt-O-W heterointerfaces. Pt/WO3-x nanoparticles supported on highly conductive rGO exhibit superior HER activity. The overpotentials of the catalyst are only 2.8 mV and 4.7 mV at 10 mA·cm-2 in acidic water and seawater, far superior to commercial 20 % Pt/C catalyst. Additionally, the catalyst can be stabilized at a current density of 30 mA·cm-2 for 180 h. This study provides a feasible strategy for rational design of Pt-based catalysts for renewable energy applications.

Identification of the toxin components of Rhizoctonia solani AG1-IA and its destructive effect on plant cell membrane structure.

Rice sheath blight is a fungal disease caused mainly by Rhizoctonia solani AG1-IA. Toxins are a major pathogenic factor of R. solani, and some studies have reported their toxin components; however, there is no unified conclusion. In this study, we reported the toxin components and their targets that play a role in R. solani AG1-IA. First, toxins produced by R. solani AG1-IA were examined. Several important phytotoxins, including benzoic acid (BZA), 5-hydroxymethyl-2-furanic aid (HFA), and catechol (CAT), were identified by comparative analysis of secondary metabolites from AG1-IA, AG1-IB, and healthy rice. Follow-up studies have shown that the toxin components of this fungus can rapidly disintegrate the biofilm structure while maintaining the content of host plant membrane components, thereby affecting the organelles, which may also explain the lack of varieties highly resistant to sheath blight.

Ultrafine Co-MoC particles in porous carbon derived from polyoxometalate-based metal organic framework for efficient hydrogen evolution reaction.

Accurately regulating ultrafine molybdenum carbide (MoC)-based catalysts is a significant challenge in the rational design of hydrogen evolution reaction (HER) electrocatalysts. Herein, under the guidance of the first principle calculations, we proposed an in-situ polyoxometalate-confined strategy for creating uniformly distributed ultrafine Co-MoC bimetallic nanoparticles in porous carbon nanostars, with the assistance of precisely designed metal-organic framework (MOF). The Co-MoC@C electrocatalyst has a high specific surface area of 969 m2·g-1 because of the conductive carbon substrate with abundant mesopores, which makes for exposing more active sites of Co-MoC nanocrystals (∼1.5 nm) and facilitating electron/ion transport. Thus, Co-MoC@C electrocatalyst shows the excellent electrochemical activity with overpotentials of 88.4 mV and 66.6 mV at a current density of 10 mA·cm-2 under acidic and alkaline conditions, respectively. The in-situ polyoxometalate-confined strategy will provide a new guideline for the design and preparation of efficient HER electrocatalysts.

MiR-320a is downregulated in patients with myasthenia gravis and modulates inflammatory cytokines production by targeting mitogen-activated protein kinase 1.

Myasthenia gravis (MG) are T-cell dependent antibody-mediated autoimmune disorders, microRNAs are important regulators of human autoimmune disease pathogenesis. Here, we investigated the miRNAs expression profiles in MG for the first time and found that miR-320a was significantly downregulated in MG patients compared to normal healthy people. Meanwhile, pro-inflammatory cytokins in MG patients were overexpressed. Furthermore, we identified MAPK1 as a direct target of miR-320a. Downregulation of miR-320a induced the overexpression of pro-inflammatory cytokins through promoting COX-2 expression. This process was modulated by ERK/ NF-κB pathways. Taken together, our findings suggested that miR-320a could play a role in modulation of inflammatory cytokins production.