Search

Codonopsis pilosula oligosaccharides (CPOs) showed promising anti-obesity effects in HFD-induced obese mice.

Herein, we report an efficient kinetic resolution of alkyl allylic alcohols enabled by an iridium-catalyzed enantioselective alkynylation of alkyl allylic alcohols with potassium alkynyltrifluoroborates. A wide range of chiral 1,4-enynes bearing various functional groups and unreacted enantioenriched allylic alcohols were obtained with excellent enantioselectivities and high kinetic resolution performance (

A highly regio- and chemoselective synthesis of 1H-isoindoliums through a novel cascade cyclization reaction of propargylamine-based 1,6-diynes has been developed.

Based on green chemistry, 3D hierarchical ZnO microflowers (MFs) constructed from layered 2D nanosheets have been designed as carriers to uniformly load PdO/Pd nanoparticles by the calcination of the precursor (ZnO/Pd(II) microflowers) in air. The ZnO/Pd(II) microflowers are prepared by dipping the 3D ZnO MFs in an ethanolic solution of PdCl2 without involving additional agents. The as-prepared 3D hierarchical ZnO microflowers are a stable support to enhance the dispersibility of PdO/Pd nanoparticles to achieve better catalytic performance for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). In addition, the synergistic effect between the PdO and Pd nanoparticles is another major driver that promotes the catalytic process. Over 98% of 4-NP is reduced within 7 min. Furthermore, structural analysis of the ZnO/PdO/Pd microflowers can provide useful information for understanding structure-performance relationships.

A novel supercapacitor material was synthesized from SiO2-coated Co3O4 and CuO nanoparticles. These nanocapsules provided large specific surface area, fast electron transport, good mechanical stability and high electrochemical activity. The specific capacitance at 1 A g−1 was 835.4 F g−1, and it had excellent cycling performance.

We designed a facile and green self-assembly route for the large-scale production of bimetallic coordination polymer–Zn(MAA)2/Pd(II) nanoribbons by employing two terminal units with distinct hard–soft properties of the smallest semi-rigid methacrylate anion (MAA−) to combine with two different metal ions. The COO− (chemically hard base) served as the initial unit, which was applied to coordinate with the Zn2+ ions for constructing the host network of this Janus CPs by facilely adjusting the proportion of ethanol/water to control the degree of solvation. After soaking in an ethanol solution of PdCl2, the alkene units (chemically soft base) act as secondary donors to load the soft noble metal Pd2+ ions and form Zn(MAA)2/Pd(II) nanoribbons, which are ideal precursors of ZnO/PdO nanoribbons. By pyrolyzing the dual metal ion equipped Zn(MAA)2/Pd(II) precursors, ZnO nanoribbon supported PdO nanoparticles (NPs) with a well-defined structure were facilely fabricated on a large scale. Furthermore, the as-obtained ZnO/PdO nanoribbons exhibit efficient catalytic performance for the reduction of 4-NP, which can convert 99.3% of the substrates within 6 min. This superior catalytic performance may be attributed to the well-dispersed PdO nanoparticles as well as the absence of additional agents introduced a green synthetic method.

DNA aptamers against carcinoembryonic antigen (CEA) have been identified through the systematic evolution of ligands by exponential enrichment (SELEX) technique, but their affinity needs to be improved. In this study, an in silico approach was firstly used to screen the mutation sequences of a reported DNA aptamer (the parent aptamer, denoted as P) against CEA. The affinities of several high-score DNA mutants were determined by the biolayer interferometry technique. Finally, the newly obtained aptamers were verified in an aptasensor application. For the in silico approach, Mfold and RNA Composer were combined to generate the 3D RNA structures of the DNA mutants. The RNA structures were then modified to 3D DNA structures with the Write program. The docking model and binding ability of the 3D DNA structures with CEA were simulated and predicted with the ZDOCK program. Two mutation sequences (P-ATG and GAC-P) exhibited significantly higher ZDOCK scores than P. The dissociation constant of P-ATG and GAC-P to CEA was determined to be 4.62 and 3.93 nM respectively, obviously superior to that of P (6.95 nM). The detection limit of the P-ATG and GAC-P based aptasensors was 1.5 and 1.2 ng mL−1, respectively, markedly better than that based on P (3.4 ng mL−1). The consistency between the in silico and the experimental results indicates that the developed in silico post-SELEX screening approach is feasible for improving DNA aptamers. The P-ATG and GAC-P aptamers found in this study could be used for future CEA aptasensor design and fabrication, promisingly applicable for highly sensitive CEA detection and early cancer diagnosis.

CuO nanoparticles (CuO NPs) with ultrasmall size (∼3.6 nm) and a highly-dispersed pattern embedded in a silica matrix were obtained in situ through a calcination process of organic copper salt. By means of rational selection of reactants, organic copper salt was introduced into Si–O–Si networks via covalent bonding during the sol–gel process under neutral conditions without any additional catalyst. The introduction of organic copper salt via covalent bonding as well as the compact Si–O–Si networks allowed for the formation of highly dispersed and ultrasmall sized CuO NPs. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the obtained silica complex had spherical morphology and well-dispersed small sized CuO NPs. The as-obtained CuO@SiO2 nanocomposites exhibited good catalytic property on the reduction of organic dye with NaBH4 as the reducing agent.

Noninvasive diagnosis of Helicobacter pylori (H. pylori) infection is very attractive. This study investigated the single strand DNA (ssDNA) acquisition method from H. pylori in dental plaque, and the integration of our previously developed 43-mer H. pylori DNA biosensor with the obtained target ssDNA (tDNA). Dental plaque samples were collected from 34 patients/volunteers, whose gastric H. pylori infection statuses were tested with the 13C urea breath test (UBT). The samples were treated with colony polymerase chain reaction (PCR) to obtain double strand DNA (dsDNA) of 104 basepairs (bp) long. A blocker ssDNA was designed and used in thermal treatment of the dsDNA to release the 104-mer tDNA, which contains the 43-mer DNA sequence in the middle. PCR primers were designed, and the tDNA releasing and detection conditions with the biosensor were optimized. The limit of detection with the biosensor was 12 fM dsDNA. The dental plaque detection results correlated quite well with the UBT results, with a sensitivity of 100%, and specificity of 97%. These results indicate that the residence of H. pylori in dental plaque is highly associated with gastric H. pylori infection, and detection of dental plaque samples with our DNA biosensor is promisingly applicable in noninvasive diagnosis of H. pylori infection.

Tuberculosis (TB) remains a significant challenge to public health, especially in developing countries. Failure in early diagnosis and lack of rapid and accurate diagnostic methods lead to ongoing prevalence and transmission of TB. Recently, the recombinase polymerase amplification (RPA) technique has made it possible to rapidly amplify and detect nucleic acids without specialized devices. We developed a RPA-based method for identifying Mycobacterium tuberculosis (MTB) by detecting mts90, a more specific target identified in our previous research. Different screening methods were employed for selecting a preferred primer pair of amplification, and probes were confirmed as very fast and reliable tools in the screening of potential primer candidates. The results showed that the mts90 RPA assay was very sensitive and capable of detecting 6 copies of recombinant plasmid containing mts90 sequence per reaction. The assay was specific for detecting MTB, as it did not identify the genomic DNA from other mycobacteria and pathogens. When applied to analyze clinical samples, including sputum, bronchoalveolar lavage fluid (BALF) and tissues, the mts90 RPA assay had a coincidence rate of 96.43% (27/28) compared to the Biochip test, which has been used in clinics for diagnosing TB. The mts90 RPA assay can be completed within 20 minutes at 39 °C without thermal cycling; its simple operation and rapid detection suggest RPA-based MTB assays could be further developed for TB diagnosis in resource-poor settings.

An efficient modular approach for the synthesis of propargylamine modified β-cyclodextrins has been developed. Using mono-(6-benzylamino-6-deoxy)-β-cyclodextrins, formaldehyde, and alkynes, mono-(6-(benzylpropargyl)amino-6-deoxy)-β-cyclodextrins have been synthesized through a three-component coupling reaction catalyzed by gold(III) salt in water at 40 °C.

Herein, an autocatalytic route to fabricate dual metal ion-equipped organic/inorganic hybrid silica, an ideal precursor for multifunctional silica-based composites integrated with well-dispersed Ag and Co3O4 nanoparticles was demonstrated. Significantly, by rational selection of reactants, such dual metal ion-equipped organic/inorganic hybrid silica can be synthesized through successive spontaneous reactions under near neutral conditions without an additional catalyst. Both the Ag+ and Co2+ ions are introduced into silica by chemical bonds, which favor the formation of small-sized and well-dispersed Ag and Co3O4 nanoparticles without aggregation in the entire silica matrix. After calcination, multifunctional silica composites equipped with well-dispersed Ag and Co3O4 nanoparticles were obtained. The as-obtained silica composites, as indicated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), have a spherical morphology and smooth surface. TEM tests also reveal the well dispersed fashion of Ag and Co3O4 nanoparticles. In addition, the obtained Ag–Co3O4@SiO2 composites exhibit good catalytic performance in the reduction of methylene blue (MB) with NaBH4 as a reducing agent, and can be readily recycled by an external magnetic field due to their superparamagnetic properties.

A new approach for selective hydroxylation of non-activated cyclohexanes using dioxirane generated in situ in water through supramolecular control has been developed. Using β-CD and γ-CD as the supramolecular hosts, selective hydroxylation of cyclohexane substrates, including trans/cis-1,4-, 1,3- and 1,2-dimethylcyclohexanes and trans/cis-decahydronaphthalene, was achieved in up to 54% yield in water. Furthermore, site-selective C–H bond hydroxylation of (+)-menthol was achieved by obstructing the approach of dioxirane to the C–H bond with higher steric hindrance through inclusion complexation with β-CD and γ-CD in water.

Pro-gastrin-releasing peptide (31–98) (ProGRP31–98) is a highly reliable, sensitive, and specific tumor marker for small cell lung cancer (SCLC). DNA aptamers for ProGRP31–98 were selected in this study from an 89-mer DNA library with a random region of 48 nucleotides (nt) flanked with two primer hybridization sites, by using the systematic evolution of ligands by the exponential enrichment (SELEX) method. The DNA sequences binding to ProGRP31–98 immobilized magnetic beads were selected by running 12 SELEX cycles and 3 negative selection cycles. The selected DNA sequences were separated by cell based DNA cloning, and then sequence analyzed. The DNA sequences obtained were screened and investigated for binding specificity to ProGRP31–98 by using electrochemiluminescence (ECL) measurement with [Ru(bpy)2dppz]2+, a molecular light-switch, as the ECL probe. One DNA sequence (89 nt) and its random region (48 nt) were identified as specific aptamers for ProGRP31–98. Based on the secondary structures of the obtained DNA aptamers, two other truncated DNA aptamers, 40 nt and 15 nt long, respectively, were identified. The obtained aptamers have strong affinities to ProGRP31–98, with a Kd value of 16 nM, and can detect ProGRP31–98 with a detection limit of 17 nM using the label-free ECL measurement.

Dye as a colored organic pollution has caused tremendous environmental problems. Removing dyes from effluents is of significant importance. Layered double hydroxides (LDHs), known as hydrotalcite-like compounds or ionic lamellar compounds, have attracted considerable attention recently due to the presence of large interlayer spaces, positively charged layers and solvation molecules. LDH-based materials are frequently used for environmental remediation especially for the elimination of dye compounds. This review compiles an extensive list of LDH-based low-cost sorbents and photocatalytic catalysts for dyes from the vast literature. Furthermore, performance, key factors and mechanisms involved in the processes are also included. Lastly, some major challenges together with prospects in this research field are discussed and highlighted. In conclusion, the application of LDH-based materials in the area of adsorption and catalysis science represents a useful and viable method, resulting in the outstanding capabilities in the removal of dyes from aqueous systems.

1,2-Pentanediol and 1,5-pentanediol with high yield (~80%) could be achieved over a simple but efficient non-precious Cu–Mg3AlO4.5 bifunctional catalyst in the hydrogenolysis of biomass-derived furfuryl alcohol. The cooperative catalysis of highly dispersed metallic Cu and basic Mg3AlO4.5 drastically increases the activity and chemoselectivity.

Coordination polymer nanoribbons equipped with dual metal ions are fabricated by using a Janus building block, which combines two parts with distinct characters, a chemically hard group to assemble the host network with Co2+ ions, and a chemically soft unit to subsequently anchor noble ions. By judiciously adjusting the desolvation process, the 1D assembly of the Janus building blocks with Co2+ ions can be readily achieved. The structure analysis and formation mechanism study of the nanoribbons provide important guidance on the design and assembly manipulation of other bifunctional molecules. Furthermore, the dual metal ion equipped nanoribbons can act as ideal precursors for 1D Pd/Co3O4 nanocomposites with excellent catalytic activity, improved durability and magnetic separation ability.

A new class of hydrogen bond donor–acceptor–donor (HB-DAD) organocatalysts has been developed for conjugate addition of benzylidene barbiturates. HB-DAD organocatalyst 1a (featuring para-chloro-pyrimidine as the hydrogen bond acceptor (HBA), N–H as the hydrogen bond donor (HBD) and a trifluoroacetyl group as the electron withdrawing group (EWG)) is able to activate benzylidene barbiturates through complementary DAD–ADA hydrogen bonding. Using 1a in benzylidene barbiturate conjugate addition, good yields were achieved. The relative rate constant (krel = 2.9) of 1a in catalyzing the conjugate addition of benzylidene barbiturates and the binding constant (KA = 8936 (±723) M−1) of 1a with benzylidene barbiturates were determined by NMR and UV/Vis. spectroscopy studies. The excellent correlation (R2 = 0.97) between the relative rate constant and binding affinity of 1a with benzylidene barbiturates provides support for the importance of DAD–ADA hydrogen bonding in organocatalysis.

In this paper, we demonstrate a facile and scalable route to the preparation of composites containing ultrasmall TiO2 nanocrystals and porous carbon matrix. In this method, the titanium ions are covalently introduced to polymer chains and transformed into TiO2 nanocrystals directly in solid matrices, which allows the generation of well dispersed TiO2 nanocrystals with small size in the entire carbon matrix. To our knowledge, this is the first time that ultrasmall TiO2 nanocrystals are incorporated into a bulk porous carbon matrix. In comparison with pure TiO2 particles, the composites exhibit significant improvement in photocatalytic degradation of methyl blue under visible light irradiation, which might be attributed to the ultrasmall size of TiO2 nanocrystals as well as the high separation efficiency of photogenerated electrons and holes based on the synergistic effect between TiO2 nanocrystals and carbon matrices. Furthermore, the composites could be easily recycled without obvious activity loss.

Stable bis-cyclometallated gold(III) complexes were developed as efficient catalysts for organic transformation reactions by using two strategies: (1) construction of distorted square planar gold(III) complexes and (2) dual catalysis by gold(III) complexes and silver salts.

The incorporation of inorganic nanoparticles (NPs) into polymers has been pursued as a route to functional materials. TiO2 is a well known multifunctional inorganic material, however, stabilizing TiO2 NPs in bulk polymer matrices to obtain optically transparent nanocomposites remains a significant challenge. Here, we report an effective strategy for the preparation of bulk transparent TiO2–polymer nanocomposites through the combined use of copolymerization of a novel titanium ion-containing monomer with a liquid–solid reaction. The titanium ions are covalently introduced into polymer chains and transformed into TiO2 NPs directly in the solid-state polymer matrices, which allows the generation of well dispersed TiO2 NPs with small size and narrow size distribution in the entire polymer matrices. The resulting transparent nanocomposites exhibit promising UV-shielding properties and consequently should have direct application in the development of transparent UV-protective materials. Moreover, the surface photocatalytic activity of the nanocomposites is helpful for realizing a pollutant- and bacteria-free surface. Moreover, europium methacrylate (Eu(MA)3) is used as a cross-linking agent, which produces cross-linked structures to enhance the stability of the nanocomposites.

Three hydrogen-bonding three-dimensional (3D) networks of ammonium carboxylate salts formed between 3,5-dinitrobenzoic acid and aminomethyl pyridine (2-, 3-, 4-) are described here. During solution crystallization, the hydrogen atom transfers from the carboxylic acid to the amine to yield ammonium carboxylate salts, which feature three charge-separated N+–H⋯O− hydrogen bonds to afford two types of one-dimensional (1D) hydrogen-bonding columns. Of the three structures, ((2-pyridylmethyl)ammonium) (3,5-dinitrobenzoate) (1) shows a hydrogen-bonding column which consists of alternating R12(4) and R24(8) rings whereas ((3-pyridylmethyl)ammonium) (3,5-dinitrobenzoate) (2) results in a hydrogen-bonding column which comprises repeating R34(10) rings. ((4-pyridylmethyl)ammonium) (3,5-dinitrobenzoate) (3) bears a unique shape of Chinese knot among four cations instead of the column constructed by rings. From this we can gather information about the possible position effects of functional groups on the overall packing.

A series of lanthanide-organic framework coordination polymers, {[La(2)(TDC)(2)(NO(3))(H(2)O)(4)](OH)·5H(2)O}(n) (1) and [Ln(TDC)(NO(3))(H(2)O)](n) (TDC = thiophene- 2, 5- dicarboxylic acid; Ln = Nd(2), Sm(3), Eu(4), Gd(5), Tb(6), Dy(7), Ho(8), Er(9), Yb(10)) have been synthesized by solvothermal reaction and characterized by elemental analysis, FT-IR, TG analysis, single-crystal X-ray diffraction and power X-ray diffraction. The single-crystal X-ray diffraction analysis results show that 1 displays a 3-D porous framework with (3,7)-connected {4(10).6(11)}{4(3)} topology. The compounds 2-10 crystallized in the same P2(1)/c space group and exhibits a (3,6)-connected {4.6(2)}(2){4(2).6(10).8(3)} topology, Right-handed and left-handed helical chains coexist in the 2-D layer structure. The luminescence properties of 2-10 and the magnetic properties of 5,7,8,9 were investigated.