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Compared with the conventional Diels–Alder reaction, the development of selective cross-Diels–Alder reactions between two different conjugated dienes, especially in a catalytic asymmetric manner, has been neglected. We now report a peri- and enantioselective cross-Diels–Alder reaction of 3-alkoxycarbonyl-2-pyrones with unactivated conjugated dienes catalysed by a copper(II)–bis(oxazoline) complex, leading to formal inverse-electron-demand adducts with high enantioselectivity under mild reaction conditions. Computational studies showed that this reaction proceeds through an ambimodal transition state: post-transition-state bifurcation leads to [2+4] and [4+2] adducts with the same enantioselectivity, followed by a facile Cope rearrangement to provide a single observed thermodynamic [2+4] product. This reaction occurs with a wide variety of cyclopentadienes, fulvenes and cyclohexadienes, providing a highly efficient and enantioselective approach to densely functionalized cis-bicyclic scaffolds. The synthetic value of this reaction is demonstrated by the asymmetric synthesis of two biologically important natural products, artemisinic acid and coronafacic acid. Periselective catalytic asymmetric cross-Diels–Alder reactions between two different conjugated dienes remain underdeveloped. Now, the selectivity challenges are overcome in such a reaction of electron-poor 2-pyrones and unactivated conjugated dienes, and an ambimodal transition state is identified.

Over the past three decades, organocatalysis has emerged as a powerful catalysis platform and has gradually been incorporated into the routine synthetic toolbox to obtain chiral molecules. However, its application in the site- and enantioselective functionalization of inactive aryl C–H bonds remains in its infancy. Here, we present an organocatalyst-controlled para-selective arene C–H functionalization strategy that addresses this issue, which remains an enduring challenge in arene functionalization chemistry. By emulating enzyme catalysis, the chiral phosphoric acid catalyst offers an ideal chiral environment for stereoinduction, and the projecting substituents give control of chemo- and site-selectivity. Various types of nucleophile are compatible with this method, affording more than 100 para-selective adducts with stereodefined carbon centres or axes in viable molecular contexts. This protocol is expected to provide a general strategy for para-selective functionalization of arene C–H bonds in a controlled manner. Although organocatalysis has emerged as a powerful catalysis platform, its application for the selective transformation of inactive arenes remains challenging. Now, an organocatalyst-controlled site-selective C–H functionalization of arenes has been developed, with wide substrate generality and applicability, offering a general strategy for arene transformation.

Arctigenin(ARG) , a natural lignans compound isolated from Arctium lappa L. In this study, the anti-tumor effect of ARG on prostate cancer cell PC-3M and the mechanism of apoptosis and autophagy induced by PI3K/Akt/mTOR signaling pathway were discussed, and further confirmed by the joint treatment of ARG and PI3K inhibitor LY294002. Here, the effect of ARG on cell viability was evaluated in PC-3M cells by CCK-8 assay. After the treatment of ARG, colony formation assay was used to detect the anti-proliferation effect. Annexin V-FITC/PI kit and DAPI staining were used to detect the apoptosis level, and cell cycle changes were analyzed by flow cytometry. The expression of autophagy was detected by acridine orange staining. In addition, the expression levels of apoptosis and autophagy-related proteins were analyzed by western blot. The result showed that different concentrations of ARG inhibited the proliferation of PC-3M cells. DAPI staining and flow cytometry showed that ARG induced PC-3M cell apoptosis and arrested cell in G0/G1 phase. Acridine orange staining showed that ARG induced autophagy in PC-3M cells. Western blot experiments showed that ARG inhibited the expression of Bcl-2 , promoted the expression of Bax and cleaved caspase-3. At the same time, the expression of autophagy-related proteins LC3B-II and Beclin-1 increased after ARG treatment, but P62 decreased. In addition, further studies have shown that treatment with LY294002 enhanced the effects of ARG on the expression of proteins associated with apoptosis and autophagy , indicating that ARG may induce apoptosis and autophagy through PI3K/Akt/mTOR pathway.

Single-crystal structures of five lanthanide-erythritol complexes are reported. The analysis of the chemical compositions and scrutinization of structural features in the single-crystal data of the complexes led us to find that unexpected deprotonation occurs on the OH group of erythritol of three complexes. Considering these complexes were prepared in acidic environments, where spontaneous ionization on an OH group is suppressed, we suggest metal ions play an important role in promoting the proton transfer. To find out why the chemically inert OH is activated, the single-crystal structures of 63 rare-earth complexes containing organic ligands with multiple hydroxyl groups (OLMHs) were surveyed. The formation of μ2-bridges turns out to be directly relevant to the occurrence of deprotonation. When an OH group from an OLMH molecule participates in the formation of a μ2-bridge, the polarization ability of the metal ions becomes strong enough to promote the deprotonation on the OH group. The above structural characteristics may be useful in the rational design of catalysts that can activate the chemically inert OH group and promote the relevant chemical conversions.

A fundamental understanding of electrolytes is critical for designing lithium-ion batteries with excellent performance and high safety. The traditional solvents in electrolytes of lithium-ion batteries are mainly ethylene carbonate and propylene carbonate. Despite their similar structures and chemical properties, ethylene carbonate-based electrolytes have been reported to enable the reversible reaction of graphite anodes, whereas propylene carbonate-based electrolytes cause the exfoliation of graphite. Herein, we have investigated the oxidation stability and the reductive decomposition of ethylene carbonate and propylene carbonate from electron-level quantum calculations. While small differences in their oxidation stability were presented, we found disparity in their reductive decomposition. The reductive product of lithium alkyl carbonate exhibits different geometrical and molecular orbitals, which was considered to influence the quality of the ethylene/propylene carbonate solvent-based solid–electrolyte interphase (SEI). This study presents the disparity of redox decomposition of ethylene carbonate–propylene carbonate in Li-ion batteries, which is expected to guide the design of new electrolyte systems, thereby enhancing the performance of Li-ion batteries.

Tumor exosomes are promising biomarkers for early cancer diagnosis in a noninvasive manner. However, precise capture and direct analysis of tumor-specific exosomes in complex biological samples are still challenging. Herein, we present a highly efficient dual-aptamer recognition system for precisely isolating and quantifying tumor exosomes from the complex biological environment based on hyperbranched DNA superstructure-facilitated signal amplification and ratiometric dual-signal strategies. When tumor exosomes were captured by the dual-aptamer recognition system, the cholesterol-modified DNA probe was anchored on the surface of the exosomes, activating DNA tetrahedron-based hyperbranched hybridization chain reaction to generate a sandwich complex. Then, the sandwich complex could bind a large number of Ru(NH3)63+ (Ru(III)), leading to a small amount of unbound Ru(III) left in the supernatant after magnetic separation. Hence, the redox reaction between Ru(II) and [Fe(CN)6]3- (Fe(III)) was significantly prevented, causing an obviously enhanced IFe(III)/IRu(III) value. Consequently, highly sensitive detection of tumor exosomes was achieved. The developed approach successfully realized direct isolation and analysis of tumor exosomes in complex sample media and human serum samples as well. More significantly, this ratiometric dual-signal mode and immobilization-free strategy effectively circumvented the systematic errors caused by external factors and the tedious probe immobilization processes, thus displaying the excellent performances of high reliability, improved accuracy, and easy manipulation. Overall, this approach is expected to offer novel ways for nondestructive early cancer diagnosis.

We report an approach that polymerizable handle-modified nanosized metal organic frameworks (MOFs) are used as independent monomers to be covalently organized by crosslinking molecules (CLMs) into an orderly MOF-assembled hybrid monolithic stationary phase, overcoming the respective problems of previously reported MOF-mixed or embedded stationary phases so far. It has a hierarchical micro-, meso-, and macropore structure throughout the monolithic matrix that is donated from MOF themselves, formed via CLM crosslinking in-between MOFs and expended by porogenic solvents, and a tunable surface chemistry derived inherently from MOFs, regulated by CLMs and initiated by the mobile phases as well. Such a pore structure and surface chemistry display multiplex interactions of sieving and electrostatic repulsion in addition to the polarity-based interactions that synergistically govern the partitioning way and degree of target molecules between the stationary and mobile phases, thus offering the ability to simultaneously separate small and large molecules during one chromatographic run on a nano-flow capillary high-performance liquid chromatography platform. A baseline mutual separation with the HETP and Rs of, for example, 9.2 μm butylbenzene and 4.56 (butylbenzene and pentylbenzene), 7.9 μm (phenylalanine) and 3.50 (tryptophan and phenylalanine), and 7.0 μm (myoglobin) and 1.91 (bovine serum albumin and myoglobin) was achieved when UiO-66/NH-methacrylate was exemplified as a model of MOFs and 1,6-hexanediol dimethacrylate and stearyl methacrylate together as CLMs. Not limited to the MOFs and CLMs demonstrated here, other available MOFs and CLMs or newly designed and synthesized ones are expected to be used for constructing one's own desired monolithic stationary phases toward her/his particular purposes.

Three polysaccharides of uniform molecular weight designated as SJP1-1, SJP2-1, and SJP3-1 from Smilacina japonica were studied in this paper. Respectively, their specific optical rotations were −45°, −75°, and −35°, their polysaccharide contents were 89.22%, 93.05%, and 59.83%, their relative average molecular weights were 1.87 × 105 Da, 1.04 × 105 Da, and 1.36 × 104 Da. Three polysaccharides were all composed mainly of the three monosaccharides mannose, glucose, and galactose, which together in SJP1–1, SJP2–1, and SJP3–1 respectively made up 96.34%, 98.23%, and 91.67% of the total polysaccharide. The polysaccharide structure was maintained mostly by β-glucose (1 → 3), β-glucose (1 → 4), α-mannose (1 → 3), and α-galactose (1 → 4) glycosidic linkages. Scanning electron microscopy showed that SJP1–1, SJP2–1, and SJP3–1 were smooth uniform microspheres with diameters of 10–20 μm that combined to form both uniformly dispersed particles and blocky structures. Finally, antioxidant assay showed that these polysaccharides all had a strong ability to scavenge ·OH and DPPH· radicals, with the effects of purified polysaccharides being greater than those of crude polysaccharides. This first report on the properties of these polysaccharides provides a basis for further studies to shed light on the medical properties of Smilacina japonica.

A highly chemoselective and enantioselective cyclization of γ-chloroenals and ketimines has been developed to synthesize enantiopure 3,4-2H-pyrindin-2-ones as major products. It is proposed that the intermediate enone IV reacted with an enamine to proceed with a [3 + 3] cyclization, thereby affording 3,4-2H-pyrindin-2-ones as major products. Interestingly, the addition of LiCl promoted the formation of the enamine and accelerated the [3 + 3] cyclization. In contrast, the [4 + 2] cycloaddition reaction between the intermediate vinyl enolate VIII and an imine offered 5,6-2H-pyrindin-2-ones as minor products. This protocol represents the exceptional potential of N-heterocyclic carbene (NHC) catalytic reactions in accessing biologically active 3,4-2H-pyrindin-2-one derivatives in good yield with high chemoselectivities and excellent enantiomeric purities.

Aconiti Lateralis Radix Praeparata (Fuzi in Chinese), which are the lateral roots of Aconitum Carmichaelii Debx, is widely used in China to treat many neurological diseases. Fuzi, in its various forms, has many neuropharmacological effects. It can act as an analgesic and help with depression, epilepsy, and dementia. However, the neuropharmacological effects of Aconiti Lateralis Radix Praeparata are seldom comprehensively reviewed. In this review, the neuropharmacological activities of some components contained in Aconiti Lateralis Radix Praeparata are considered. These include aconitine, mesaconitine, hypaconitine, total alkaloid, polysaccharide-1, benzoylmesaconine, fuziline, songorine, and napelline. We also specifically discuss the antidepressant effects of total alkaloids and polysaccharide-1. This review may provide a theoretical basis for further utilization of Aconiti Lateralis Radix Praeparata for diseases that affect the central nervous system.

An enzyme inhibition-based lab-in-a-syringe (EI-LIS) device was developed by integrating a 1-naphthol-linked bi-enzymatic reaction (sensor core) into the LIS (sensor device) for point-of-need monitoring of pesticide residues. The integration relies on the rational design of two reaction pads. The conjugate pad is a polyester fiber membrane loaded with plant-esterase, an alternative to acetylcholinesterase. Besides pesticide capture, plant-esterase also mediates the hydrolysis of 1-naphthyl acetate, generating 1-naphthol. The detection pad is an agarose gel entrapping oxidized 3,3',5,5'-tetramethylbenzidine (oxTMB) from Fe(iii) meso-tetra(N-methyl-4-pyridyl) porphyrin (FeTMPyP4)-catalyzed TMB oxidation. Both pads were embedded into their cartridges and then connected to a syringe. Under syringe pumping, 1-naphthol vertically flowed from the conjugate to the detection cartridge, linking the two pads. If plant-esterase was intact, 1-naphthol would reduce oxTMB, causing a color change of the detection pad from blue to colorless. If the plant-esterase activity was inhibited by pesticides, less 1-naphthol was produced, and the blue color of the detection pad would be partially or wholly retained. The deeper the blue color, the greater the pesticide concentration. This chromogenic pattern is responsible for a highly sensitive readout (detection limits of dichlorvos: 0.1 nM with the naked eye and 0.07 nM with a spectrometer).

We developed a competitive coordination-based immobilization-free electrochemical biosensor for highly sensitive and selective detection of arsenic(v) using a CeO2-DNA nanoprobe, which effectively circumvented complicated modification procedures and successfully achieved arsenic(v) determination in natural water samples.

We developed a label-free homogeneous electrochemical cytosensor for ultrasensitive detection of cancer cells based on multiaptamer-functionalized DNA tetrahedral nanostructures, which avoided expensive labeling and sophisticated immobilization procedures, providing opportunities for precisely detecting cancer cells in clinical applications.

Summary Fucosylation and its fucosidic linkage-specific motifs are believed to be essential to understand their distinct roles in cellular behavior, but their quantitative information has not yet been fully disclosed due to the requirements of ultra-sensitivity and selectivity. Herein, we report an approach that converts fucose (Fuc) to stable europium (Eu) isotopic mass signal on hard ionization inductively coupled plasma mass spectrometry (ICP-MS). Metabolically assembled azido-fucose on the cell surface allows us to tag them with an alkyne-customized Eu-crafted bacteriophage MS2 capsid nanoparticle for Eu signal multiplication, resulting in an ever lowest detection limit of 4.2 zmol Fuc. Quantitative breakdown of the linkage-specific fucosylation motifs in situ preserved on single cancerous HepG2 and paracancerous HL7702 cells can thus be realized on a single-cell ICP-MS platform, specifying their roles during the cancering process. This approach was further applied to the discrimination of normal hepatocellular cells and highly, moderately, and poorly differentiated hepatoma cells collected from real hepatocellular carcinoma tissues., Graphical abstract, Highlights • Switching facile fucose to stable Eu mass signal on a single-cell ICP-MS platform • Ever lowest LOD of 4.2 zmol FucAz was achieved using a Eu-decorated MS2 nanoparticle • Single-cell breakdown of fucosidic linkage-specific motifs • Discrimination of highly, moderately, and poorly differentiated HCC from normal ones, Chemistry; Analytical Chemistry; Biochemistry

The cinchona-alkaloid-catalyzed cycloaddition reactions of 2-cyclohexenone with tropone and various heptafulvenes give [8+2] or [4+2] cycloadducts, depending on the substituents present on the heptafulvene. We report the results of new experiments with heptafulvenes, containing diester and barbiturate substituents, which in combination with computational studies were performed to elucidate the factors controlling [8+2] vs [4+2] cycloaddition pathways, including chemo-, regio-, and stereoselectivities of these higher-order cycloadditions. The protonated cinchona alkaloid primary amine catalyst reacts with 2-cyclohexenone to form a linear dienamine intermediate that subsequently undergoes a stepwise [8+2] or [4+2] cycloaddition. Both tropone and the different heptafulvenes initially form [8+2] cycloadducts. The final product is ultimately decided by the reversibility of the [8+2] cycloaddition and the relative thermal stability of the [4+2] products. The stereoisomeric transition states are distinguished by the steric interactions between the protonated catalyst and tropone/heptafulvenes. The [8+2] cycloaddition of barbiturate-heptafulvene afforded products with an unprecedented trans-fusion of the five- and six-membered rings, while the [8+2] cycloadducts obtained from cyanoester-heptafulvene and diester-heptafulvene were formed with a cis-relationship. The mechanism, thermodynamics, and origins of stereoselectivity were explained through DFT calculations using the ωB97X-D density functional.

High mobility group box 1 (HMGB1) is a nuclear protein that is released on injury triggers inflammation. This study aims to elucidate the effects of salidroside on diabetes-induced liver inflammation. The levels of glucose, inflammatory cytokines and hepatic functional parameters in serum and liver of type 2 diabetic db/db mice were examined. Immunohistochemistry, immunofluorescence and western blot tests were performed to determine the mechanisms underlying the action. Palmitic acid (PA) or HMGB1-stimulated was adopted as an in vitro cell model. Salidroside treatment improved glucose tolerance, lipid profiles while decreased the production of inflammatory cytokines. It also reduced the levels of serum biochemical markers. In addition, salidroside inhibited HMGB1 signaling pathway in db/db mice. In the salidroside treatment significantly inhibited PA or HMGB1 induced inflammatory signaling pathway, too. HMGB1 inhibitors and HMGB1 knockdown both hindered PA-induced HMGB1 signaling pathway, showing the same effect as salidroside. Salidroside treatment significantly alleviates insulin resistance, hyperglycemia and hepatic inflammation in db/db mice, and also showed beneficial to PA-stimulated. Salidroside proves to control hyperglycemia and hepatic inflammation via inhibiting HMGB1/RAGE/NF-κB and HMGB1/TLR4/NLRP3 signaling pathways.

A syringe-aided apta-nanosensing method is reported for the colorimetric determination of acetamiprid. The method employs double-stranded (ds) DNA-conjugated gold nanoparticle@magnetic agarose beads, i.e., dsDNA-AuNP@MABs as peroxidase-mimicking composite probes, in which the aptamer is indirectly attached to the AuNP surface through its hybridization with complementary DNA (cDNA). Upon contact with the acetamiprid target, the probes can give perceptible color change due to the possible conformation switch from dsDNA’s brush-like to cDNA’s ‘pancake’ regime. An “air-spaced pumping” procedure using a syringe equipped with ring magnets as the operation platform was proposed to facilitate the magnetic separation of the sensing probes. Therefore, the analytical steps can be easily accomplished in a syringe, including probe loading, acetamiprid capture and magnetic separation from crude samples, chromogenic reagent loading and colorimetric visualization. Acetamiprid concentration down to 3.3 ppb can be easily identified by the naked eye. The final solution also can be transferred for quantitative measurement. Under spectrometer, the ratio of the absorbance at 652 nm in the presence and absence of acetamiprid (A/A0) is linearly related to the acetamiprid concentration in the 0.4–4.5 ppb range. The limit of detection is calculated to be 0.24 ppb. Moreover, satisfactory recoveries ranging from 90.90 to 91.82% with relative standard deviations of ≤2.96% were obtained in analyzing real spiked samples.

Ginseng (G) and Prepared Rehmannia Root (PRR) are commonly used in traditional Chinese medicine for blood supplementation. This study aimed to study G and PRR with different compatibility ratios changes in chemical composition and inhibition of cyclophosphamide-induced myelosuppression. HPLC was used to determine the chemical constituents of 13 ginsenosides, 5-hydroxymethylfurfural (5-HMF) and verbascoside in different proportions of G-PRR. Balb/c mice were injected intraperitoneally with cyclophosphamide (CTX) to induce bone marrow suppression. The effects of different proportions of G-PRR on peripheral blood, bone marrow nucleated cells, thymus and spleen index of myelosuppressed mice were analyzed. The results showed that the compatibility of G and PRR can promote the dissolution of ginsenosides, and the content of conventional ginsenosides decreased, and the content of rare ginsenosides increased. Different proportions of G-PRR increased the number of peripheral blood and bone marrow nucleated cells in cyclophosphamide-induced bone marrow suppression mice (p < 0.01), increased thymus index (p < 0.01), decreased spleen index (p < 0.01). Different proportions of G-PRR can improve the myelosuppression induced by cyclophosphamide in mice, and the combined effect of G-PRR is better than the single decoction of G and PRR. Among them, G-PRR 2 : 3 and G-PRR 1 : 2 were better than the other groups. These results indicate that different proportion of G-PRR can improve bone marrow suppression, and the combined decoction of G-PRR is better than the separate Decoction in improving bone marrow suppression. This improvement may be related to the changes of the substance basis and active ingredients of G-PRR.

Quantum dots (QDs) have attracted great interest in fluorescence sensing. However, due to the surface passivation of QDs, it is still challenging to develop a sensing method based on the direct use...

Background: Ginseng black spot disease resulting from Alternaria panax Whuetz is a common soil-borne disease, with an annual incidence rate higher than 20–30%. In this study, the bacterial strains with good antagonistic effect against A. panax are screened. Methods: A total of 285 bacterial strains isolated from ginseng rhizosphere soils were screened using the Kirby–Bauer disk diffusion method and the Oxford cup plate assay. We analyzed the antifungal spectrum of SZ-22 by confronting incubation. To evaluate the efficacy of biocontrol against ginseng black spot and for growth promotion by SZ-22, we performed pot experiments in a plastic greenhouse. Taxonomic position of SZ-22 was identified using morphology, physiological, and biochemical characteristics, 16S ribosomal DNA, and gyrB sequences. Results: SZ-22 (which was identified as Brevundimonas terrae) showed the strongest inhibition rate against A. panax, which showed 83.70% inhibition, and it also provided broad-spectrum antifungal effects. The inhibition efficacies of the SZ-22 bacterial suspension against ginseng black spot reached 82.47% inhibition, which is significantly higher than that of the 25% suspension concentrate azoxystrobin fungicide treatment (p

Two Ho(C6H13NO)3(NO3)3 complexes formed by holmium nitrate and N-tert-butylacetamide (NtBA) (Ho-NtBA(I) in a Cc space group, and Ho-NtBA(II) in a P21/c space group) are reported here to investigate the coordination of lanthanide ions with amide groups. Using X-ray single crystal diffraction, FTIR, Raman, FIR and THz methods the structures of the two complexes were identified, in which Ho3+ is 9-coordinated to three carbonyl oxygen atoms provided by three NtBA ligands and three bidentate nitrate ions to form the “facial” and “meridional” isomers. Their FTIR and Raman spectra indicate the formation of two holmium complexes, the variations of NtBA after holmium coordination and the spectra are similar for the isomers in some extent. Their FIR and THz spectroscopic results show the coordination of holmium ions and THz maybe more sensitive to isomers. The results demonstrate the coordination behaviors of holmium ions and NtBA ligand.

3A2g → 3T1g(P) transition band of Ni2 + is used to probe the coordination of Ni2 +. Two-dimensional asynchronous spectra (2DCOS) are generated using the D ouble A synchronous O rthogonal S ample D esign (DAOSD), A synchronous S pectrum with A uxiliary P eaks (ASAP) and Two-Trace Two-Dimensional (2T2D) approaches. Cross peaks relevant to the 3A2g → 3T1g(P) transition band of Ni2 + are utilized to probe coordination between Ni2 + and various ligands. We studied the spectral behavior of the 3A2g → 3T1g(P) transition band when Ni2 + is coordinated with ethylenediaminetetraacetic acid disodium salt (EDTA). The pattern of cross peaks in 2D asynchronous spectrum demonstrates that coordination brings about significant blue shift of the band. In addition, the absorptivity of the band increases remarkably. The interaction between Ni2 + and galactitol is also investigated. Although no clearly observable change is found on the 3A2g → 3T1g(P) transition band when galactitol is introduced, the appearance of cross peak in 2D asynchronous spectrum demonstrates that coordination indeed occurs between Ni2 + and galactitol. Furthermore, the pattern of cross peak indicates that peak position, bandwidth and absorptivity of the 3A2g → 3T1g(P) transition band of Ni(galactitol)x2 + is considerably different from those of Ni(H2O)62 +. Thus, 2DCOS is helpful to reveal subtle spectral variation, which might be helpful in shedding light on the physical-chemical nature of coordination.

Ti3SiC2 and Ti3AlC2 are two promising binders for the ultrahard composite polycrystalline cubic boron nitride (PcBN). In this study, the cBN composites with Ti3SiC2 and Ti3AlC2 binders with different binder contents were synthesized under the same high pressure (~5.5 GPa) and high temperature (1350 °C) conditions. Their mechanical properties were measured separately, including Vickers hardness, bending hardening, and compression hardening. Together with XRD results, the phase compounds were also investigated. The decomposition and reaction processes were affected by binder content. Some new compounds formed during sintering, these compounds were TiC, TiSi2, SiC, TiB2, SiB4, TiB2, and TiC0.7N0.3 in Ti3SiC2-cBN composites, as well as TiC0.7N0.3, TiB2, and AlN in Ti3AlC2-cBN composites. The microstructure of the cracks surface was obtained after the bending tests, and was used to further investigate and compare their crack mode by SEM. The crack surface profile and elementary analysis on the oxidative surface were also discussed.

A remote cross Rauhut−Currier reaction utilizing vinyl ketones and para-quinone methides derived from isatins was realized, which was successfully catalyzed using bifunctional phosphines, furnishing chiral 3,3-disubstituted oxindoles in excellent enantioselectivities and high yields. The mechanistic studies demonstrated the key role of the alkyl hydrogen of the vinyl ketones, which conceivably interacted with the para-quinone methide carbonyl group via the hydrogen bond, offering a new insight for the design of novel asymmetric reactions.

Ionic liquid-based ultrasonic-assisted extraction (ILUAE) was successfully applied to the extraction of the four chromones (prim-O-glucosylcimifugin, cimifugin, 5-O-methylvisammioside, and sec-O-glucosylhamaudol) from Saposhnikovia divaricata (Radix Saposhnikoviae) for the first time. A series of l-alkyl-3-methylimidazolium ILs differing in anion and cation compositions was evaluated for extraction efficiency, and [C3MIM]Br was selected as the optimal solvent. In addition, ultrasound extraction parameters were optimized, and the chromones were directly quantified and analyzed by rapid resolution liquid chromatography-electrospray ionization/mass spectrometry (RRLC-ESI/MS). The optimal conditions were as follows: 0.4 M concentration of [C3MIM]Br, 20:1 solvent to solid ratio, and ultrasonic time, temperature, and frequency of 5 min, 40 °C, and 50 kHz, respectively. This approach obtained the highest extraction yield of 10.188 ± 0.473 mg g−1 for total chromones. Compared with regular UAE, the proposed approa...

Autophagy and apoptosis are closely associated with various pathological and physiological processes in cell cycles. Investigating the dynamic changes of intracellular active molecules in autophagy and apoptosis is of great significance for clarifying their inter-relationship and regulating mechanism in many diseases. In this study, we develop a dual-ratiometric fluorescent nanoprobe for quantitatively differentiating the dynamic process of superoxide anion (O2•–) and pH changes in autophagy and apoptosis in HeLa cells. A rhodamine B-loaded mesoporous silica core was used as the reference, and fluorescence probes for pH and O2•– measurement were doped in the outer layer shell of SiO2. Then, chitosan and triphenylphosphonium were modified on the surface of SiO2. The experimental results showed that the nanoprobe is able to simultaneously and precisely visualize the changes of mitochondrial O2•– and pH in HeLa cells. The kinetics data revealed that the changes of pH and O2•– during autophagy and apoptosis i...

Quantitative information on a targeted analyte in a complex biological system is the most basic premise for understanding its involved mechanisms, and thus precise diagnosis of a disease if it is a so-called biomarker. Here, we designed and synthesized a neodymium (Nd)-cored tag [1,4,7,10-tetraazacyclododecane-1,4,7-trisacetic acid (DOTA)–Nd complex together with a light-harvesting antenna aminofluorescein (AMF, λex/em = 494/520 nm), AMF–DOTA–Nd] with duplex signals, second near-infrared (NIR) window luminescence (λem = 1065 nm, 2.5 μs), and stable isotopic mass (142Nd). AMF–DOTA–Nd covalently linked with a urea-based peptidomimetic targeting group, 2-[3-(1,3-dicarboxypropyl)-ureido]pentanedioic acid (DUPA)-8-Aoc-Phe-Phe-Cys (DUPAaFFC) (DUPAaFFC–AMF–DOTA–Nd), allowing us to detect and quantify prostate-specific membrane antigen (PSMA) and its splice variants (total PSMA, tPSMA), which was set as an example of targeted biomarkers in this study, using NIR and inductively coupled plasma mass spectrometry (IC...

Arctigenin (ARG) is famous in its abundant pharmacological activity. However, many researches in it entered the bottleneck period because of its poor water solubility. The derivatives of ARG have been synthesised with five amino acids which have t-Butyloxy carbonyl (BOC) as a protective group. We examined the effects of removing BOC. The results showed that the amino acid derivatives without protective group have better water solubility and nitrite-clearing ability than ARG. Based on these results, ARG6′ and ARG9′ were selected at a dosage of 40 mg/kg to evaluate their antitumour activity. The percentage inhibition rate of ARG6′ and ARG9′ were 55.87 and 51.40, respectively, which was twice as much as ARG. Furthermore, they could increase liver and kidney indexes and produce less damage in these organs. In brief, this study provides a basis for new drug development.

Cubic boron nitride (cBN)-based composites were prepared from cBN–Al and cBN–TiC mixtures, respectively, under high pressure and high temperature (HPHT). During sintering, Al reacted with cBN and produced AlN and AlB2, while TiC did not react with cBN. With increasing Al from 5–20 wt-%, the strength of the cBN-based composites decreased first, then increased. AlN and AlB2 could strengthen the cBN-based composites to a certain extent. In the preparation from cBN–TiC, 10 wt-% addition of TiC was the optimal formulation to obtain the densest microstructure. Hardness of the two kinds of composites displayed different tendencies. On the other hand, cBN-based composites were treated at 1200°C for 1200 s. It was found that the isothermal oxidation process could be described by parabolic laws with slight oxidation scales formed on samples’ surfaces in different morphologies.

Lei Li,1 Jinguang Wu,2 Shifu Weng,2 Limin Yang,3 Huizi Wang,4 Yizhuang Xu,2 Keng Shen1 1Department of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, People’s Republic of China; 2Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People’s Republic of China; 3State Key Laboratory of Nuclear Physics and Technology, Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871, People’s Republic of China; 4Medical Science Research Center, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, People’s Republic of ChinaCorrespondence: Keng ShenDepartment of Obstetrics and Gynecology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, No. 1 Shuai Fu Yuan, Eastern District, Beijing 100730, People’s Republic of ChinaTel +86 10 6915 6204Fax +86 10 6915 5653Email kengshen_pumch@sina.comYizhuang XuBeijing National Laboratory for Molecular Sciences, State Key Laboratory for Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, Peking University, No. 202 Chengfu Road, Haidian District, Beijing 100871, People’s Republic of ChinaTel +86 10 6275 2689Email xuyzh_peking@sina.comPurpose: Ovarian cancer is the most lethal of gynecological malignancies. Dihydroartemisinin (DHA), a derivative of artemisinin (ARS), has profound effects against human tumors. The aim of this study was to provide a convenient, cost-efficient technique, Fourier transform infrared (FTIR) spectroscopy, to monitor and evaluate responses to DHA-induced growth inhibition of ovarian cancer cells.Methods: Cell growth and viability and the 50% inhibitory concentration (IC50) of DHA were assessed by the MTT assay. FTIR spectroscopy was used to monitor cells following DHA treatment, and data were analyzed by OMNIC 8.0 software.Results: DHA can decrease the viability of ovarian cancer cells and normal cells, but cancer cells were more sensitive to this drug than normal cells. Spectral differences were observed between cells with or without DHA treatment. In particular, an increase in the amount of lipids and nucleic acids was observed. The band intensity ratio of 1454/1400, and the intensity of the band 1741 cm− 1 increased, indicating stronger absorption after DHA treatment. Moreover, the differences were larger for the cell lines that were more sensitive to DHA.Conclusion: The spectral features provided information about important molecular characteristics of the cells in response to chemicals. These findings demonstrated the possible use of FTIR spectroscopy to evaluate DHA-induced growth inhibition effects in ovarian cancer cells and provided a promising new tool for monitoring cell growth and the effects of antitumor drugs in the clinic in the future.Keywords: ovarian cancer, artemisinin, ARS, dihydroartemisinin, DHA, fourier transform infrared spectroscopy, FTIR spectroscopy, growth inhibition

Background and Purpose: High mobility group box 1 (HMGB1) is a nuclear protein that is released on injury triggers inflammation. This study aims to elucidate the effects of salidroside on diabetes-induced liver inflammation. Experimental Approach: The levels of glucose, inflammatory cytokines and hepatic functional parameters in serum and liver of type 2 diabetic db/db mice were examined. Immunohistochemistry, immunofluorescence and western blot tests were performed to determine the mechanisms underlying the action. Palmitic acid (PA) or HMGB1–stimulated was adopted as an in vitro cell model. Key Results: Salidroside treatment improved glucose tolerance, lipid profiles while decreased the production of inflammatory cytokines. It also reduced the levels of serum biochemical markers. In addition, salidroside inhibited HMGB1 signaling pathway in db/db mice. In the salidroside treatment significantly inhibited PA or HMGB1 induced inflammatory signaling pathway, too. HMGB1 inhibitors and HMGB1 knockdown both hindered PA-induced HMGB1 signaling pathway, showing the same effect as salidroside. Conclusion: Salidroside treatment significantly alleviates insulin resistance, hyperglycemia and hepatic inflammation in db/db mice, and also showed beneficial to PA-stimulated. Salidroside proves to control hyperglycemia and hepatic inflammation via inhibiting HMGB1/RAGE/NF-κB and HMGB1/TLR4/NLRP3 signaling pathways. Funding Statement: This research was supported by National Natural Science Foundation of China (81400800). Declaration of Interests: The authors declare that they have no conflict of interest Ethics Approval Statement: All animal experiments were conducted in accordance with animal ethics of Zhengzhou University.

A chiral N-heterocyclic carbene (NHC)-catalyzed [4 + 2] annulation of γ-chloroenals and α-arylidene pyrazolinones was developed in the absence of expensive oxidants. The reaction proceeds smoothly via a vinyl enolate intermediate to afford spirocyclohexane pyrazolones in moderate to good yield (up to 86%) with high diastereoselectivities (up to 15:1 dr) and excellent enantioselectivities (up to >99% ee).

Counting and recognizing single bacterial cells are crucial to the diagnosis of bacterium-induced disease and study of cell-to-cell variability as well as the related antibiotic resistance mechanism. A higher sensitive and selective method has always been desired for a more accurate single bacterial cell analysis. We report a lanthanide-encoding inductively coupled plasma (ICP) mass spectrometric approach for counting and recognizing single bacterial cells for the first time. When noncanonical alkyne-d-alanine ( aDA) was added to five typical bacterial strains of Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Shigella dysenteriae, and Vibrio parahemolyticus, aDA was metabolically assembled into the peptidoglycan layer-supported bacterial cell wall followed by post-clickable europium-tagging with 1,4,7,10-tetraazacyclododecane-1,4,7-tris-acetic acid-10-azidopropyl ethylacetamide-europium complex ( azide-DOTA-Eu). Such Eu-tagged bacterial cells can be deemed as Eu-engineered particles, delivering more than 5 orders of magnitude self-signal-amplification outcome relative to the single bacterial cells themselves when 151/153Eu is determined by single particle ICP mass spectrometry ( spICPMS). This metabolic assembly of aDA mediated Eu-encoding signal amplification strategy breaks through the detection limit of spICPMS and ensures that we directly count a single bacterial cell. The individual bacterial strains we counted can be simultaneously recognized through their corresponding lanthanide (Ln)-coded polyclonal antibody (Ln = 139La, 141Pr, 142Nd, 152Sm, and 160Gd, respectively), serving as a specific bacterial identification (Ln- pAb-ID). Moreover, the developed approach was applied to show the different behavior between genetically identical Staphylococcus aureus under the treatments of vancomycin and Ag nanoparticles, demonstrating that such a lanthanide-encoding spICPMS approach provided a new way to discover still ambiguous cell-to-cell variability.

Traditional electrochemical hydrogen peroxide (H2O2) assays all indispensably require the immobilization of enzyme or nanomaterials on electrode surface. These complex electrode surface modifications are laborious and time-consuming. To overcome such limitations, we developed here a facile homogeneous electrochemical biosensor based on displacement reaction for detection of intracellular and extracellular H2O2 produced by living cells. Methylene blue-labeled short single-stranded DNA strand (DNA-MB) was ingeniously designed as the reporter, which was adsorbed on CeO2 nanoparticles to result in low electrochemical signal. In the presence of H2O2, DNA-MB was released from CeO2 nanoparticles, leading to the significant enhancement of current signal. Therefore, a simple homogeneous electrochemical H2O2 assay is successfully achieved. This strategy also displays excellent anti-interference capability and reproducibility for H2O2 determination. More importantly, this method was capable of conveniently realizing intracellular and extracellular H2O2 assay. Thus, with the excellent merits of simplicity, rapidness, good repeatability, high specific and sensitivity, the proposed strategy has great potential to be applied in exploring the roles of H2O2 in physiological and pathological processes.

Astaxanthin, which is an important metabolite with anti-oxidative property, has been discovered in some fish, shrimp, and microorganisms. Owing to the great advantages of microalgae-based astaxanthin in the aspects of sustainability and safety, microalgal astaxanthin is emerging into the limelight. In the past years, researchers isolated a couple of microalgal species and explored the synthesis pathways of astaxanthin in algal cells. Also, specific culture conditions, such as nitrogen deficiency, high-intensity illumination, and supply of glucose, salt or trace elements, promoting the accumulation of astaxanthin in microalgal cells have been intensively studied. The main goal of this paper is to review the progresses in the production of microalgal astaxanthin and promote the wide use of microagal astaxanthin in aquaculture. In this regard, we summarized the studies on algal strains screening, synthetic mechanisms of microalgal astaxanthin, microalgae cultivation models, and fish-rearing with astaxanthin supplement. Based on the literature review, we discussed the challenges threatening the production and application of microalgal astaxanthin and pointed out the prospects of microalgal astaxanthin in the future. This work will provide a deep understanding of microalgal astaxanthin and its application in aquaculture.

A size-controllable and facile synthetic strategy has been developed to fabricate a series of hollow mesoporous silica nanoparticles (HMSNs) with tunable hollow cores or shell thicknesses by employing gold nanoparticles (Au NPs) and cetyltrimethylammonium bromide (CTAB) as dual templates. Various sizes of Au NPs and different amounts of tetraethyl orthosilicate contributed to structure-tailored mesoporous silica-coated Au NPs. After calcination, CTAB molecules were completely removed, and Au NPs could still support the silica shell due to the high melting point. HMSNs were ultimately obtained by etching Au NPs. Applications of HMSNs as nanocarriers for delivering drugs were investigated. Significantly, it was flexible and convenient to control drug-loading/releasing behavior of HMSNs just by tuning the hollow cores or shell thicknesses. Intracellular experiments have proven that HMSNs are suitable for delivering drugs. We anticipate that this study could provide an important avenue for the synthesis of HMSNs and further contribute to advancing practical applications of HMSNs in drug delivery systems.

The fabrication of well-behaved drug delivery systems that can transport drugs to specifically treat cancer cells rather than normal cells is still a tremendous challenge. A novel drug delivery system with two types of tumor-related mRNAs as "keys" to open the multiple valves of the nanocarrier to control drug release was developed. Hollow mesoporous silica nanoparticles were employed as the nanocarrier and dual DNAs targeting two intracellular mRNAs were employed as "multi-locks" to lock up the nanocarrier. When the nanocarrier enters the cancer cells, the overexpressed endogenous mRNA keys hybridize with the DNA multi-locks to open the valves and release the drug. Each single mRNA could not trigger the opening of the locks to release the cargo. Therefore, the nanocarrier can be applied for specific chemotherapy against cancer cells with minor side effects to normal cells. The current strategy could provide an important avenue towards advancing the practical applications of drug delivery systems used for cancer therapy.

Detection of organophosphorus pesticides (OPPs) is crucial for food safety and environmental protection. Here, we propose an enzyme-free strategy for the detection of phosphorothiolate pesticides, a major class of OPPs with P–S bonds, by using hyaluronan–tyrosine–gold nanoparticles (HA–Tyr–AuNPs) as the colorimetric probe. The strategy is based on the concept that the surface of AuNPs can be directly modified by the hydrolyzate of the phosphorothiolate in a strongly basic HA–Tyr–AuNP colloidal solution, which in turn affects the aggregation state of AuNPs and hence produces a red-to-blue color change. This method is very simple in design and easy to operate. The detection requires only the addition of the analyte into the HA–Tyr–AuNP colloidal solution at room temperature. By virtue of the absorbance variations of the analytical system, the limit of detection for phorate is as low as 0.005 μg mL−1 (i.e., 0.006 mg kg−1), which is lower than the maximum residue limit (MRL) allowed by the European Union. More importantly, phorate residues in real samples can be directly detected by this method.

Arctigenin (ARG), a nature medicine with many pharmacological activities, was poorly soluble in water and placed restriction on practical usage. Six novel arctigenin monoester derivatives were obtained from the reflux reaction with arctigenin, carboxylic acids (crotonic acid, furoic acid, 2-naphthalene acid and indol-3-acetic acid), EDCI and DMAP in dichloromethane at 60°C for 4-6h and their properties on nitrite scavenging assay were investigated in vitro. Based on the results, the one of the most effective derivatives, arctigenin β-indolylacetate (ARG6), was selected to study anti-tumor activity in vivo at doses of 20 and 40mg/kg. The results showed that comparison with ARG group, ARG6 exhibited more anti-tumor activity in H22 tumor-bearing mice. Furthermore, ARG6 exhibited less damage to the liver, kidney, spleen and thymus when compared with those in positive group. Biochemical parameters of ALT, AST, BUN and Cre showed ARG6 had little toxicity to mice as well. ARG6 significantly improved serum cytokine levels of IL-2, IL-6, IFN-γ and TNF-α, and decreased VEGF compared with ARG. Moreover, H & E staining, TUNEL assay and immunohistochemical of tumor issues also indicated that ARG6 exhibited anti-tumor activity in vivo. In brief, the present study provide a method to improve ARG anti-tumor activity and provide a reference for new anti-tumor agent.

MicroRNAs (miRNAs) and reactive oxygen species (ROS) are concurrently implicated in heart ischemia-reperfusion (IR) injury. There may exist mutual cross-talk between miRNAs and ROS in cardiac IR injury process. In this study, we developed a novel crown-like silica@polydopamine-DNA-CeO2 nanocomposite by assembly of silica@polydopamine-DNA1 nanoparticles decorated with satellite CeO2-DNA2 nanoparticles for detecting and imaging of microRNA-21 (miR-21) and hydrogen peroxide (H2O2) in simulated IR injury in living cells and in vivo. The miRNA-21 was found to be regulated by H2O2 via PI3K/AKT signaling pathway for the first time in H9C2 cells in simulated ischemia-reperfusion injury. H2O2 and miRNA-21 are overproduced during mimicked heart ischemia-reperfusion injury, suggesting that they are closely related to reperfusion injury. All these results reveal that there is definite cross-talk between miR-21 and H2O2 in IR injury. The current method can provide a promising strategy to further explore the interplayi...

Low-abundance tyrosine phosphorylation is crucial to not only normal but also aberrant life processes. We designed and synthesized a photocleavable magnetic nanoparticle-based gallium tag for tagging and enrichment as well as UV-release of the phosphate-bearing molecules/ions in cells. HPLC/71Ga species-unspecific isotope dilution (71Ga-SUID) ICPMS was subsequently developed for specific and absolute quantification of phosphotyrosine (pY) under the assistance of a protein tyrosine phosphatase-1B (PTP-1B). pY quantification was thus achieved via determination of Ga in the Ga-phosphate complexes that come exclusively from the Ga-tagged pY. In this way, the method detection limit of pY reached down to 30 amol with the RSD lower than 5.70% (n = 5 at pmol level). Feasibility of this proposed method was validated using VNQIGTLSEpYIK, VNQIGTLpSEpYIK, and extracellular regulated protein kinase 1 peptide (-pTEpY-) standards with the recovery of more than 96% (n = 5). It was applied to the absolute quantification o...

In this study, a recently developed superhard and high-performance composite of cubic boron nitride–titanium silicon carbide (cBN–Ti3SiC2) is fabricated at high-pressure and high-temperature (HPHT) condition. The mechanical properties of this superhard material are investigated using the comparisons of the bending, compression hardening, and Vicker hardness test. Its microstructural properties are characterized by X-ray diffraction and scanning electron microscopy. The influence of the binder Ti3SiC2 is determined by changing the mass ratio. The composites with common binders, namely, TiC and SiC2, are sintered under the same HPHT condition to investigate the characteristics of cBN–Ti3SiC2 composites.

Abnormal pH values in the organelles are closely associated with inappropriate cellular functions and many diseases. Monitoring subcellular pH values and their variations is significant in biological processes occurring in living cells and tissues. Herein, we develop a series of ratiometric fluorescence nanoprobes for quantification and imaging of pH values with a single-wavelength excitation in cytoplasm, lysosomes, and mitochondria. The nanoprobes consist of mesoporous silica nanoparticles assembled with aminofluorescein as the recognition unit for pH measurement and ethidium bromide as reference fluorophore. Further conjugation of subcellular targeting moiety enables the nanoprobes to specifically target lysosome and mitochondria. Confocal fluorescence imaging demonstrated that the nanoprobes could effectively monitor the pH fluctuations from 5.0 to 8.3 in living cells by ratio imaging with 488 nm excitation. Subcellular pH determination and imaging in lysosome and mitochondria could also be achieved in different conditions. The current method can offer a general strategy to determine subcellular analytes and investigate the interactions in biological samples.

Cubic boron nitride (cBN)-based composites were prepared at ~ 5.5 GPa and ~ 1350 °C with different mass ratios of cBN-Ti3AlC2 mixtures as starting materials. Ti3AlC2 decomposed and reacted with cBN during high pressure and high temperature (HPHT) sintering. TiC, TiC0.7N0.3, TiB2, and AlN were then formed. The bending and compressive strengths of cBN-based composites first increased and then decreased when the Ti3AlC2 content increased from 5 wt.% to 40 wt.%; hardness was determined by both the compactness and binder content. cBN-based composites sintered with 20 wt.% Ti3AlC2 possessed the highest bending strength (422.45 MPa), compressive strength (3969.14 MPa), and hardness (3381.58 HV); they also had the most compact microstructure. The initial oxygenation temperature of the cBN-based composites sintered with 20 wt.% Ti3AlC2 was about 850 °C. After isothermal oxidation at 1200 °C for 1200 s, titanium and aluminum oxides formed on the surface with pores and cracks. The isothermal oxidation process of the cBN-based composites could be described by a parabolic law.

The novel cesium chloride–lactose complex (CsCl·C12H22O10 (Cs-Lac), cesium chloride- d -arabinose and l -arabinose complexes (CsCl·C5H10O5, Cs-D-Ara and Cs-L-Ara) have been synthesized and characterized using X-ray diffraction, FTIR, FIR, THz and Raman spectroscopies. Cs+ is 9-coordinated to two chloride ions and seven hydroxyl groups from five lactose molecules in Cs-Lac. In the structures of CsCl- d -arabinose and CsCl- l -arabinose complexes, two kinds of Cs+ ions coexist in the structures. Cs1 is 10-coordinated with two chloride ions and eight hydroxyl groups from five arabinose molecule; Cs2 is 9-coordinated to three chloride ions and six hydroxyl groups from five arabinose molecules. Two coordination modes of arabinose coexist in the structures. α- d -arabinopyranose and α- l -arabinopyranose appear in the structures of Cs-D-Ara and Cs-L-Ara complexes. FTIR and Raman results indicate variations of hydrogen bonds and the conformation of the ligands after complexation. FIR and THz spectra also confirm the formation of Cs-complexes. Crystal structure, FTIR, FIR, THz and Raman spectra provide detailed information on the structure and coordination of hydroxyl groups to metal ions in the cesium chloride–lactose, cesium chloride-D- and l -arabinose complexes.

Potassium ion plays an important role in a variety of bioactivities, and many functions of potassium ion are exerted via coordination with saccharides. Up to now, the understanding of the biochemistry of K+/saccharides system is limited due to the lack of crystal structures of potassium ion-saccharide complexes. Herein, we have prepared single crystal of potassium chloride-α- d -glucose complex (KCl·2C6H12O6) and its crystal structure has been successfully obtained. Potassium ion is coordinated to two α- d -glucose molecules. One α- d -glucose molecule provides 4α and 6β hydroxyl groups to coordinate to potassium ion, another one uses its 2α and 3β hydroxyl groups to coordinate to potassium ion. The single crystal structure of the complex exhibits some unusual structural features. K⋯K dimer is suggested to form because of shorter K⋯K distance (3.059 A). Moreover, unusually short O⋯Cl distances between 2.3 and 2.5 A are found in the crystal. Based on the crystal structure of the complex and the fact no free OH stretching vibrational absorption band is observed in FTIR spectra of the complex, assignment of hydrogen bonding linkage is achieved. Coordination with potassium ion brings about considerable structure variation on the glucose moiety of the complex. The structural changes can be reflected in the corresponding FTIR, Raman, FIR and THz spectra.

An acetamiprid-binding aptamer (ABA), gold nanoparticles (AuNPs) and upconversion nanoparticles (UCNPs) are used in a colorimetric and fluorometric method for the ultrasensitive and selective detection of the pesticide acetamiprid. The ABA is first configured into a duplex with a complementary DNA covalently attached to AuNPs. The resulting dsDNA-functionalized AuNP probe is not stable in 0.15 M NaCl solution and aggregates. This causing the color to change from red to purple. In the presence of acetamiprid, the ABA undergoes a structural switch from a DNA duplex to an aptamer-acetamiprid complex and consequently dissociates from the AuNPs. The partially unhybridized AuNPs are stable against salt-induced aggregation and show red color. The ratio of absorbances at 524 nm (red) and 650 nm (purple blue) varies with the concentration of acetamiprid in the 0.025–10 μM concentration range. The colorimetric signal can be further amplified by introducing DNA-modified carboxylated UCNPs (silica-coated NaYF4:Yb,Er) which display red and green fluorescence under 980 nm excitation. An inner filter effect occurs between DNA-modified UCNPs and dsDNA-modified AuNPs. The fluorometric assay is based on the measurement of the ratio of red (654 nm) and green (540 nm) fluorescence and works in the 0.025 to 1 μM acetamiprid concentration range and has a 0.36 nM detection limit (at a signal-to-noise ratio of 3). Because of the specificity of the aptamer, the assay is high selective. It was successfully used to quantify acetamiprid in contaminated real samples.

A double-decrease strategy is described for ultrasensitive determination of the fungicide and vulcanization additive ziram. The assay principle is inspired by the interaction of ziram with gold nanoparticles (AuNPs). In this process, zinc ions are released, and ziram adsorption induces the aggregation of the AuNPs. The aggregated AuNPs decrease the intensity of the fluorescence of CdSe/ZnS quantum dots (QDs) capped with 3-mercaptopropionic acid via an inner filter effect. This is a result of the overlap between the absorption band of aggregated AuNPs (peaking at 680 nm) and the yellow emission of QDs (peaking at 608 nm). Zinc also exerts another decrease effect on the fluorescence of the CdSe/ZnS QDs, probably via a static quenching mechanism. Based on this double-decrease effect, ultrahigh sensitivity is achieved for ziram. The fluorescence response of the QDs (Ex / Em = 380/608 nm) is immediate. The relative fluorescence intensity is proportional to the ziram concentration within a wide range of 5 nM to 4 μM in two consecutive linear ranges. The limit of detection is as low as ~2 nM (signal-to-noise ratio of 3), which is much lower than the maximum residue limit defined by the EU pesticide database. It is also found that a similarly high sensitivity is obtained for another fungicide ferbam. Graphical abstract An ultrasensitive detection strategy for ziram was developed based on the doubledecrease effect of AuNPs and zinc ions on the fluorescence of CdSe/ZnS QDs.

This paper aims to design a simple and rapid way to extract and determination of oleanolic acid from Clematis mandshurica Rupr. (C. mandshurica), and to disclose the protective effect of the acid on neural function and early brain injury after subarachnoid haemorrhage. To this end, an orthogonal test was performed to examine the effects of ultrasonic-assisted extraction (UAE) variables (i.e. liquid-material ration, time, temperature and frequency) on the extraction of oleanolic acid from C. mandshurica. Then, the oleanolic acid from C. mandshurica was quantified and analysed by liquid chromatography with photodiode array detection (LC-DAD), and the fraction of oleanolic acid was collected by automatic fraction collector. Finally, the author investigated how oleanolic acid influences the neural function and early brain injury after subarachnoid haemorrhage. Through the analysis, the highest oleanolic acid yield of 0.7192% was obtained with the extraction temperature of 70°C, extraction frequency of 90kHz, extraction time of 10min and liquid-material ratio of 30:1. Meanwhile, significant improvement of neural function was observed in the oleanolic acid group of 20mg/kg, and the model group suffered from much more serious neural function injuries than the sham-operated group. This means the oleanolic acid group of 20mg/kg can effectively reduce the cerebral vascular permeability caused by subarachnoid haemorrhage. This research reveals the protective mechanism of oleanolic acid on protection against early brain injury after subarachnoid haemorrhage in rats.

A chiral N-heterocyclic carbene-catalyzed benzoin condensation reaction in water has been developed, affording α-hydroxy ketones in good to high yields and high enantioselectivities. Water was proposed as a proton shuttle in the aqueous asymmetric condensation reaction.