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991.
Kun Xu Xiuling Li Pengzuo Chen Dan Zhou Changzheng Wu Yuqiao Guo Lidong Zhang Jiyin Zhao Xiaojun Wu Yi Xie 《Chemical science》2015,6(1):283-287
Ferromagnetic two-dimensional (2D) ultrathin nanosheets hold great promise for next generation electronics. Ferromagnetic metal-free materials that usually possess only an s/p electronic configuration with weak spin–orbit coupling and a large spin relaxation time, would play an important role in constructing future spintronic devices. However, the absence of an intrinsic spin ordering structure in most metal-free materials greatly hampers the widening scope of ferromagnetic 2D nanostructures as well as in-depth understanding of their ferromagnetic nature. Herein, the induction of intrinsic ferromagnetism in 2D metal-free g-C3N4 ultrathin nanosheets has been achieved through a new effective strategy whereby hydrogen dangling bonds are introduced. In our case, g-C3N4 ultrathin nanosheets with hydrogen dangling bonds showed obvious room temperature ferromagnetic behavior that could even be tuned by the concentration of hydrogen. This work will pave a new pathway to engineer the properties of 2D nanomaterial systems. 相似文献
992.
Zhijun Zhang Yijia Guan Meng Li Andong Zhao Jinsong Ren Xiaogang Qu 《Chemical science》2015,6(5):2822-2826
Sandwich ELISA methods have been widely used for biomarker and pathogen detection because of their high specificity and sensitivity. However, the main drawbacks of this assay are the cost, the time-consuming procedure for the isolation of antibodies and their poor stability. To overcome these restrictions, we herein fabricated artificial antibodies based on imprinting technology and developed a sandwich ELISA for pathogen detection. Both the capture and detection antibodies were obtained via an in situ method, with simplicity, rapidity and low cost. The peroxidase mimics, the CeO2 nanoparticles, as signal generators were integrated with the detection antibody. The fabricated artificial antibodies exhibited not only natural antibody-like binding affinities and selectivities, but also superior stability and reusability. The detection limit was about 500 CFU mL–1, which is much lower than that of traditional ELISA methods (104 to 105 CFU mL–1). Furthermore, the capture antibody can disinfect pathogens in situ. 相似文献
993.
Various strategies have been proposed for the detection of disease protein biomarkers; however, most methods are too expensive, cumbersome or limited in sensitivity for clinical use. Here, we report that a fabricated complex can be used as a powerful tool to detect trace proteins in complex samples. In this strategy, a DNA–protein complex that comprises of one target molecule and two or more deoxyribozyme-containing probes can exhibit autonomous cleavage behavior on the surface of the substrate DNA modified electrode. In the meantime, the complex can remove the cleaved DNA fragment from the electrode surface by taking advantage of the proximity effect. The proposed approach allows one-step and highly sensitive detection of a variety of targets based on the changes of the direct electrochemical readout. Moreover, this method may also have considerable advantages over the commonly reported DNA amplification-assisted immunoassays, particularly in terms of assay simplicity and cost, which may hold great potential for application in resource-constrained regions. 相似文献
994.
Qiurong Shi Peina Zhang Yijing Li Haibing Xia Dayang Wang Xutang Tao 《Chemical science》2015,6(7):4350-4357
We have successfully produced open-mouthed, yolk–shell (OM-YS) Au@AgPd nanoparticles (NPs) via galvanic replacement reaction at room temperature; each NP has a large opening on its AgPd shells. Owing to the openings on the AgPd shells, the inner surfaces of the AgPd shells of as-prepared OM-YS Au@AgPd NPs become accessible to the surrounding media. These new structural characters make the present OM-YS Au@AgPd NPs excellent catalysts for electrochemical oxidation of ethanol in alkaline media. Their electrochemical active surface area is 87.8 m2 g–1 and the mass activity is 1.25 A mgPd–1. Moreover, the openings on the AgPd shells also make the surfaces of the Au cores in OM-YS Au@AgPd NPs accessible to the reaction media, which significantly facilitates the removal of CO and other carbonaceous intermediate species, thus leading to substantially enhanced durability and stability. This superior electrocatalytic performance cannot be implemented by using conventional YS Au@AgPd NPs or commercially available Pd/C catalysts. 相似文献
995.
Wei Hong Shaoyun Chen Bin Sun Mark A. Arnould Yuezhong Meng Yuning Li 《Chemical science》2015,6(5):3225-3235
This study utilized high temperature NMR and matrix-assisted laser desorption/ionization time-of-flight (MALDI-ToF) mass spectrometry to reveal that appreciable amounts of structural defects are present in the diketopyrrolopyrrole (DPP)–quaterthiophene copolymers (PDQT) synthesized by the Stille coupling polymerization with Pd(PPh3)2Cl2, Pd2(dba)3/P(o-tol)3, and Pd(PPh3)4 catalyst systems. It was proposed that these structural defects were produced via homocoupling side reactions of the C–Br bonds and the organostannane species. Model Stille coupling reactions further substantiated that the amount of structural defects are catalyst-dependent following the order of Pd(PPh3)2Cl2 > Pd2(dba)3/P(o-tol)3 > Pd(PPh3)4. To verify the structural assignments, “perfect” structurally regular PDQT polymers were prepared using Yamamoto coupling polymerization. When compared to the structurally regular polymers, the polymers containing defects exhibited notable redshifts in their absorption spectra. Surprisingly, the “perfect” structurally regular polymers showed poor molecular ordering in thin films and very low charge transport performance as channel semiconductors in organic thin film transistors (OTFTs). On the contrary, all the “defected” polymers exhibited much improved molecular ordering and significantly higher charge carrier mobility. 相似文献
996.
Mark Forster Richard J. Potter Yichuan Ling Yi Yang David R. Klug Yat Li Alexander J. Cowan 《Chemical science》2015,6(7):4009-4016
Intrinsic doping of hematite through the inclusion of oxygen vacancies (VO) is being increasingly explored as a simple, low temperature route to preparing active water splitting α-Fe2O3–x photoelectrodes. Whilst it is widely accepted that the introduction of VO leads to improved conductivities, little else is verified regarding the actual mechanism of enhancement. Here we employ transient absorption (TA) spectroscopy to build a comprehensive kinetic model for water oxidation on α-Fe2O3–x. In contrast to previous suggestions, the primary effect of introducing VO is to block very slow (ms) surface hole – bulk electron recombination pathways. In light of our mechanistic research we are also able to identify and address a cause of the high photocurrent onset potential, a common issue with this class of electrodes. Atomic layer deposition (ALD) of Al2O3 is found to be particularly effective with α-Fe2O3–x, leading to the photocurrent onset potential shifting by ca. 200 mV. Significantly TA measurements on these ALD passivated electrodes also provide important insights into the role of passivating layers, that are relevant to the wider development of α-Fe2O3 photoelectrodes. 相似文献
997.
Lei Li Yunpeng Liu Cheng Ma Jingyao Qu Angie D. Calderon Baolin Wu Na Wei Xuan Wang Yuxi Guo Zhongying Xiao Jing Song Go Sugiarto Yanhong Li Hai Yu Xi Chen Peng George Wang 《Chemical science》2015,6(10):5652-5661
Quantification, characterization and biofunctional studies of N-glycans on proteins remain challenging tasks due to the complexity, diversity and low abundance of these glycans. The availability of structurally defined N-glycan (especially isomer) libraries is essential to help solve these tasks. We report herein an efficient chemoenzymatic strategy, namely Core Synthesis/Enzymatic Extension (CSEE), for rapid production of diverse N-glycans. Starting with 5 chemically prepared building blocks, 8 N-glycan core structures containing one or two terminal N-acetyl-d-glucosamine (GlcNAc) residue(s) were chemically synthesized via consistent use of oligosaccharyl thioethers as glycosylation donors in a convergent fragment coupling strategy. Each of these core structures was then extended to 5 to 15 N-glycan sequences by enzymatic reactions catalyzed by 4 robust glycosyltransferases. Success in synthesizing N-glycans with Neu5Gc and core-fucosylation further expanded the ability of the enzymatic extension. Meanwhile, high performance liquid chromatography with an amide column enabled rapid and efficient purification (>98% purity) of N-glycans in milligram scales. A total of 73 N-glycans (63 isomers) were successfully prepared and characterized by MS2 and NMR. In summary, the CSEE strategy provides a practical approach for “mass production” of structurally defined N-glycans, which are important standards and probes for glycoscience. 相似文献
998.
Xiangrui Yang Shichao Wu Yang Li Yu Huang Jinyan Lin Di Chang Shefang Ye Liya Xie Yuan Jiang Zhenqing Hou 《Chemical science》2015,6(3):1650-1654
Delicate mesoscopic architectures, bearing complex forms with multiple hierarchy levels, lead to significant functions in biogenic minerals. Herein, a bio-inspired approach was developed to fabricate comet-shaped assemblies of an anti-tumor drug – 10-hydroxycamptothecin (HCPT). The anti-solvent co-precipitation of HCPT and the excipient – PEG-b-PLGA – within the emulsifier leads to the immediate nucleation of comet bundles, followed by a secondary nucleation to generate the comet head, which is an assembly of nanofibers aligned almost in parallel. The continuous manufacturing furnishes drug–excipient hybrid particles with high drug-loading and a sustained drug release profile. This simple and efficient bio-inspired approach led to a promising sustained local drug delivery system, and could be extended to the fabrication of other functional organic materials bearing mesoscopic structural units. 相似文献
999.
1000.
Xinchen Kang Wenting Shang Qinggong Zhu Jianling Zhang Tao Jiang Buxing Han Zhonghua Wu Zhihong Li Xueqing Xing 《Chemical science》2015,6(3):1668-1675
We proposed a strategy to synthesize mesoporous inorganic salt particles using the special properties of ionic liquid (IL) mixtures, and hollow mesoporous LaF3, NdF3, and YF3 particles were synthesized and characterized using different techniques. The size of the mesopores in the salt particles was about 4 nm, and the materials were full of crystal defects. The LaF3, NdF3 and YF3 particles were used as the catalysts for the cyanosilylation reaction of benzaldehyde using trimethylsilyl cyanide, and Ru/LaF3 and Ru/NdF3, in which Ru nanocatalysts were supported on the LaF3 and NdF3 particles with mesopores, were used to catalyze hydrogenations of benzene to cyclohexane and levulinic acid (LA) to γ-valerolactone (GVL). It was discovered that the activities of these catalysts were unprecedentedly high for these reactions. Detailed study showed that both the crystal defects and the mesopores in the salt particles played crucial roles for the extremely high catalytic activity. 相似文献