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1.
Thermo‐triggered Release of CRISPR‐Cas9 System by Lipid‐Encapsulated Gold Nanoparticles for Tumor Therapy
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Dr. Peng Wang Dr. Lingmin Zhang Prof. Wenfu Zheng Dr. Liman Cong Zhaorong Guo Yangzhouyun Xie Le Wang Rongbing Tang Qiang Feng Prof. Yoh Hamada Prof. Kohsuke Gonda Prof. Zhijian Hu Prof. Xiaochun Wu Prof. Xingyu Jiang 《Angewandte Chemie (International ed. in English)》2018,57(6):1491-1496
CRISPR/Cas9 system is a powerful toolbox for gene editing. However, the low delivery efficiency is still a big hurdle impeding its applications. Herein, we report a strategy to deliver Cas9‐sgPlk‐1 plasmids (CP) by a multifunctional vehicle for tumor therapy. We condensed CPs on TAT peptide‐modified Au nanoparticles (AuNPs/CP, ACP) via electrostatic interactions, and coated lipids (DOTAP, DOPE, cholesterol, PEG2000‐DSPE) on the ACP to form lipid‐encapsulated, AuNPs‐condensed CP (LACP). LACP can enter tumor cells and release CP into the cytosol by laser‐triggered thermo‐effects of the AuNPs; the CP can enter nuclei by TAT guidance, enabling effective knock‐outs of target gene (Plk‐1) of tumor (melanoma) and inhibition of the tumor both in vitro and in vivo. This AuNPs‐condensed, lipid‐encapsulated, and laser‐controlled delivery system provides a versatile method for high efficiency CRISPR/Cas9 delivery and targeted gene editing for treatment of a wide spectrum of diseases. 相似文献
2.
In the present work, a new porous low density lipoprotein (LDL) adsorbent membrane is prepared by 60Co γ‐ray irradiation‐induced grafting copolymerization of polypropylene (PP) non‐woven fabric with acrylic acid, followed by immobilizing heparin covalently. The amount of carboxyl group and heparin on the resultant PP non‐woven fabric is determined by titration and colorimetry, respectively. The new adsorbent membrane is characterized by attenuated total reflection Fourier transform infrared spectroscopy, scanning electron microscope, and contact angle microscopy. Static adsorption and hemoperfusion tests indicate this new adsorbent can efficiently and selectively remove LDL from human plasma. Meanwhile, good adsorption of triglyceride (TG) is also obtained. The best result is achieved by the adsorbent membrane P0.45‐A15‐H, where 33.3 ± 2.9 µg of LDL‐C, 14.7 ± 1.9 µg of high density lipoprotein cholesterol (HDL‐C), 64.9 ± 4.3 µg of total cholesterol (TC), and 202.4 ± 5.7 µg of TG are removed from human plasma per square centimeter. Hemocompability and toxicity tests show this new adsorbent membrane has good blood compatibility and low toxicity. Considering the adsorbent performance, safety, low cost, and simple preparation, this new adsorbent membrane has potential clinical application for removal of LDL. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
3.
Yi Cai Min Zhao Zhibo Guan Xue Han Miao Wang Chunjie Zhao 《Biomedical chromatography : BMC》2019,33(10)
Semen descurainiae oil (SDO) is an important traditional Chinese medicine that was recently discovered to have the function of reducing blood lipids. Metabolomics analyses of plasma, liver and kidney in rats were performed using 1H‐NMR and LC–MS to illuminate the lower blood lipid concentration effect of SDO, and niacin was considered as the active control. The measure of total cholesterol (TC) and low‐density‐lipoprotein cholesterol (LDL‐C) in plasma showed that SDO treatment decreased significantly the content of TC and LDL‐C. An orthogonal partial least squares–discriminant analysis approach was applied to identify the different metabolic profiles of plasma, liver and kidney in rats and to detect related potential biomarkers. The results suggested that the metabolic profiles of the control group and hyperlipidemia group showed significant difference and the SDO and niacin group had effective anti‐hyperlipidemia function. The biomarkers primarily concern lipid metabolism, amino acid metabolism and glycometabolism, and the change in biomarkers indicated that hyperlipidemia could cause the unbalance of these metabolic pathways in vivo. SDO reduced blood lipids by repairing amino acid and lipid metabolism. 相似文献
4.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(38):11652-11655
For the first time total structure determination of homoleptic alkynyl‐protected gold nanoclusters is reported. The nanoclusters are synthesized by direct reduction of PhC≡CAu, to give Au44(PhC≡C)28 and Au36(PhC≡C)24. The Au44 and Au36 nanoclusters have fcc‐type Au36 and Au28 kernels, respectively, as well as surrounding PhC≡C‐Au‐C2(Ph)Au‐C≡CPh dimeric “staples” and simple PhC≡C bridges. The structures of Au44(PhC≡C)28 and Au36(PhC≡C)24 are similar to Au44(SR)28 and Au36(SR)24, but the UV/Vis spectra are different. The protecting ligands influence the electronic structures of nanoclusters significantly. The synthesis of these two alkynyl‐protected gold nanoclusters indicates that a series of gold nanoclusters in the general formula Aux (RC≡C)y as counterparts to Aux (SR)y can be expected. 相似文献
5.
Yan Lyu Shasha He Jingchao Li Yuyan Jiang He Sun Yansong Miao Kanyi Pu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(50):18365-18369
Noninvasive regulation of CRISPR/Cas9 gene editing is conducive to understanding of gene function and development of gene therapy; however, it remains challenging. Herein, a photolabile semiconducting polymer nanotransducer (pSPN) is synthesized to act as the gene vector to deliver CRISPR/Cas9 plasmids into cells and also as the photoregulator to remotely activate gene editing. pSPN comprises a 1O2‐generating backbone grafted with polyethylenimine brushes through 1O2‐cleavable linkers. NIR photoirradiation spontaneously triggers the cleavage of gene vectors from pSPN, resulting in the release of CRISPR/Cas9 plasmids and subsequently initiating gene editing. This system affords 15‐ and 1.8‐fold enhancement in repaired gene expression relative to the nonirradiated controls in living cells and mice, respectively. As this approach does not require any specific modifications on biomolecular components, pSPN represents the first generic nanotransducer for in vivo regulation of CRISPR/Cas9 gene editing. 相似文献
6.
Ting Wang Yong Liu Huan‐Huan Sun Bin‐Cheng Yin Bang‐Ce Ye 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5436-5440
We have developed an ingenious method, termed Cas9 nickase‐based amplification reaction (Cas9nAR), to amplify a target fragment from genomic DNA at a constant temperature of 37 °C. Cas9nAR employs a sgRNA:Cas9n complex with a single‐strand nicking property, a strand‐displacing DNA polymerase, and two primers bearing the cleavage sequence of Cas9n, to promote cycles of DNA replication through priming, extension, nicking, and displacement reaction steps. Cas9nAR exhibits a zeptomolar limit of detection (2 copies in 20 μL of reaction system) within 60 min and a single‐base discrimination capability. More importantly, the underlying principle of Cas9nAR offers simplicity in primer design and universality in application. Considering the superior sensitivity and specificity, as well as the simple‐to‐implement, rapid, and isothermal features, Cas9nAR holds great potential to become a routine assay for the quantitative detection of nucleic acids in basic and applied studies. 相似文献
7.
Prof. Jingjing Yang Dr. Kaiyong Yang Shiyu Du Wen Luo Prof. Chao Wang Dr. Hongmei Liu Kunguo Liu Zhibin Zhang Dr. Yanfeng Gao Prof. Xin Han Prof. Yujun Song 《Angewandte Chemie (International ed. in English)》2023,62(37):e202306863
CRISPR system-assisted immunotherapy is an attractive option in cancer therapy. However, its efficacy is still less than expected due to the limitations in delivering the CRISPR system to target cancer cells. Here, we report a new CRISPR/Cas9 tumor-targeting delivery strategy based on bioorthogonal reactions for dual-targeted cancer immunotherapy. First, selective in vivo metabolic labeling of cancer and activation of the cGAS-STING pathway was achieved simultaneously through tumor microenvironment (TME)-biodegradable hollow manganese dioxide (H-MnO2) nano-platform. Subsequently, CRISPR/Cas9 system-loaded liposome was accumulated within the modified tumor tissue through in vivo click chemistry, resulting in the loss of protein tyrosine phosphatase N2 (PTPN2) and further sensitizing tumors to immunotherapy. Overall, our strategy provides a modular platform for precise gene editing in vivo and exhibits potent antitumor response by boosting innate and adaptive antitumor immunity. 相似文献
8.
Mengyi Yang Ruirui Sun Pujuan Deng Yuzhuo Yang Wenjuan Wang Jun-Jie Gogo Liu Chunlai Chen 《Chemical science》2021,12(38):12776
RNA-guided Streptococcus pyogenes Cas9 (SpCas9) is a sequence-specific DNA endonuclease that works as one of the most powerful genetic editing tools. However, how Cas9 locates its target among huge amounts of dsDNAs remains elusive. Here, combining biochemical and single-molecule fluorescence assays, we revealed that Cas9 uses both three-dimensional and one-dimensional diffusion to find its target with high efficiency. We further observed surprising apparent asymmetric target search regions flanking PAM sites on dsDNA under physiological salt conditions, which accelerates the target search efficiency of Cas9 by ∼10-fold. Illustrated by a cryo-EM structure of the Cas9/sgRNA/dsDNA dimer, non-specific interactions between DNA ∼8 bp downstream of the PAM site and lysines within residues 1151–1156 of Cas9, especially lys1153, are the key elements to mediate the one-dimensional diffusion of Cas9 and cause asymmetric target search regions flanking the PAM. Disrupting these non-specific interactions, such as mutating these lysines to alanines, diminishes the contribution of one-dimensional diffusion and reduces the target search rate by several times. In addition, low ionic concentrations or mutations on PAM recognition residues that modulate interactions between Cas9 and dsDNA alter apparent asymmetric target search behaviors. Together, our results reveal a unique searching mechanism of Cas9 under physiological salt conditions, and provide important guidance for both in vitro and in vivo applications of Cas9.Nonspecific interactions between DNA ∼8 bp downstream of the PAM and lysines within residues 1151–1156 of Cas9 mediate one-dimensional diffusion and cause asymmetric target search regions flanking the PAM. 相似文献
9.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(22):6564-6568
Bimetallic nanoparticle encapsulation in microporous zeolite crystals is a promising route for producing catalysts with unprecedented reaction selectivities. Herein, a novel synthetic approach was developed to produce PtZnx nanoclusters encapsulated inside zeolite micropores by introducing Pt2+ cations into a zincosilicate framework via ion exchange, and subsequent controlled demetallation and alloying with framework Zn. The resulting zeolites featured nanoclusters with sizes of approximately 1 nm, having an interatomic structure corresponding to a PtZnx alloy as confirmed by pair distribution function (PDF) analysis. These materials featured simultaneous shape and substrate specificity demonstrated by the selective production of p‐chloroaniline from the competitive hydrogenation of p‐chloronitrobenzene and 1,3‐dimethyl‐5‐nitrobenzene. 相似文献
10.
Reka Geczy Niels Johan Christensen Kim K. Rasmussen Ildik Klomista Manish K. Tiwari Pratik Shah Seong Wook Yang Morten J. Bjerrum Peter W. Thulstrup 《Angewandte Chemie (International ed. in English)》2020,59(37):16091-16097
Fluorescent, DNA‐stabilized silver nanoclusters (DNA‐AgNCs) are applied in a range of applications within nanoscience and nanotechnology. However, their diverse optical properties, mechanism of formation, and aspects of their composition remain unexplored, making the rational design of nanocluster probes challenging. Herein, a synthetic procedure is described for obtaining a high yield of emissive DNA‐AgNCs with a C‐loop hairpin DNA sequence, with subsequent purification by size‐exclusion chromatography (SEC). Through a combination of optical spectroscopy, gel electrophoresis, inductively coupled plasma mass spectrometry (ICP‐MS), and small‐angle X‐ray scattering (SAXS) in conjunction with the systematic study of various DNA sequences, the low‐resolution structure and mechanism of the formation of AgNCs were investigated. Data indicate that fluorescent DNA‐AgNCs self‐assemble by a head‐to‐head binding of two DNA hairpins, bridged by a silver nanocluster, resulting in the modelling of a dimeric structure harboring an Ag12 cluster. 相似文献
11.
Ronok Zahan Sinthyia Ahmed Tahmida Sharmin Mohammad A. Halim Md. Sifat Rahi Md. Chanmiya Sheikh Ryuta Miyatake Ennio Zangrando Tarannum Naz Md. Al‐Amin‐Al‐Azadul Islam Md Abu Reza 《应用有机金属化学》2021,35(1)
A novel bis[benzyl‐N′‐hydrazinecarbodithioato‐κ2 N′,S]nickel(II) complex was synthesized and characterized by means of various physical, chemical, and spectroscopic techniques. The X‐ray single crystal diffraction analysis indicated two independent close comparable bis‐chelated square planar complexes of trans‐configuration, where S‐benzyl dithiocarbazate (SBDTC) ligand is coordinated via N,S‐donor set. The complex is able to inhibit Ehrlich ascites carcinoma (EAC) cell proliferation by 51.81% and 75.75%, with 0.3 and 50 mg kg?1 (dose adjusted) dose, respectively, administered intraperitoneally for five successive days in mice model. Apoptotic cell morphological changes were examined using optical and fluorescence microscopy techniques. Expression pattern of apoptosis regulatory genes in EAC cells treated with the synthesized nickel(II) complex for five consecutive days showed an increased expression of P53, Bax, Cas‐8, Cas‐9, Cas‐3, Cyt‐c, and TNF‐α proapoptotic genes and decreased expression of antiapoptotic Bcl‐2 gene. The Ni(II) complex and Bleomycin (standard drug) were used in molecular docking coupled with molecular dynamics simulation studies with the aim to support the experimental results and to investigate the apoptotic effect towards the targeting apoptotic genes. Both experimental and computational studies reveal that the nickel(II) complex inhibits EAC cells growth successfully, suggesting a potential compound for cancer treatment. 相似文献
12.
Zhi‐Xin Yuan Stanley I. Rapoport Steven J. Soldin Alan T. Remaley Ameer Y. Taha Matthew Kellom Jianghong Gu Maureen Sampson Christopher E. Ramsden 《Biomedical chromatography : BMC》2013,27(4):422-432
Linoleic acid (LA) and LA‐esters are the precursors of LA hydroperoxides, which are readily converted to 9‐ and 13‐hydroxy‐?octadecadienoic acid (HODE) and 9‐ and 13‐oxo‐?octadecadienoic acid (oxo ODE) metabolites in vivo. These four oxidized LA metabolites (OXLAMs) have been implicated in a variety of pathological conditions. Therefore, their accurate measurement may provide mechanistic insights into disease pathogenesis. Here we present a novel quadrupole time‐of‐flight mass spectrometry (Q‐TOFMS) method for quantitation and identification of target OXLAMs in rat plasma. In this method, the esterified OXLAMs were base‐hydrolyzed and followed by liquid–liquid extraction. Quantitative analyses were based on one‐point standard addition with isotope dilution. The Q‐TOFMS data of target metabolites were acquired and multiple reaction monitoring extracted‐ion chromatograms were generated post‐acquisition with a 10 ppm extraction window. The limit of quantitation was 9.7–35.9 nmol/L depending on the metabolite. The method was reproducible with a coefficient of variation of <18.5%. Mean concentrations of target metabolites in rat plasma were 57.8, 123.2, 218.1 and 57.8 nmol/L for 9‐HODE, 13‐HODE, 9‐oxoODE and 13‐oxoODE, respectively. Plasma levels of total OXLAMs were 456.9 nmol/L, which correlated well with published concentrations obtained by gas chromatography/mass spectrometry (GC/MS). The concentrations were also obtained utilizing a standard addition curve approach. The calibration curves were linear with correlation coefficients of >0.991. Concentrations of 9‐HODE, 13‐HODE, 9‐oxoODE and 13‐oxoODE were 84.0, 138.6, 263.0 and 69.5 nmol/L, respectively, which were consistent with the results obtained from one‐point standard addition. Target metabolites were simultaneously characterized based on the accurate Q‐TOFMS data. This is the first study of secondary LA metabolites using Q‐TOFMS. Published 2012. This article is a U.S. Government work and is in the public domain in the USA. 相似文献
13.
Mojtaba Alipour 《International journal of quantum chemistry》2014,114(4):255-260
As an important lineage of metal oxides, alkaline earth oxides have attracted significant interest due to their unique properties and potential applications in material science and industry. In this article, we present the first ab initio (HF, MP2, and CCSD(T)) and density functional theory (TPSSh functional) investigation on the optical properties such as polarizabilities per atom (PPA), differential polarizability per unit (DPPU), and anisotropies of (BeO)n [n = 2–9] nanoclusters as an illustrative example of alkaline earth oxides nanostructures. Basis set augmentation effects on the studied properties of BeO nanoclusters have been explored by using basis sets of triple‐zeta quality starting from 6‐311G with increasing completeness of the diffuse and polarization functions to the 6‐311+G(3df) basis. Checking carefully the basis set effects, it is shown that the 6‐311+G(3d) basis set provides the best compromise between the accuracy and computational cost. We found a decreasing trend for PPA values of BeO nanoclusters using all considered methods, indicating the strong electron delocalization with increasing cluster size. Moreover, in accordance with the energetic analysis of stability of BeO nanoclusters, the values of PPA show that the (BeO)4 and (BeO)6 clusters are the most stable magic numbers compared to the neighbors, satisfying the minimum polarizability principle. The computed values of DPPU demonstrate a strong binding effect in BeO nanoclusters. Taking into account the electron correlation correction (ECC), it is observed that the variations of ECC on dipole polarizabilities are almost smooth for clusters under study. © 2013 Wiley Periodicals, Inc. 相似文献
14.
A convergent total synthesis of 13‐hydroxyisocyclocelabenzine was developed. (3S)‐Methyl 3‐amino‐3‐phenylpropanoate ( 4 ) was used as the chiral building block. The 3,4‐dihydro‐4‐hydroxyisoquinolin‐1(2H)‐one derivative ( 5 ), the key fragment for the total synthesis, was prepared by a novel base‐catalyzed lactone‐lactam ring enlargement (Scheme 3). The resulting target C(13) epimers 3a / 3b from macrocyclization (Scheme 4) were separated by repeated flash chromatography. The absolute configuration of the synthetic alkaloid was determined by an X‐ray crystal‐structure analysis, which enabled us to determine the absolute configuration (9S,13R) for natural 3a with positive [α]D. 相似文献
15.
This Concept article provides an elementary discussion of a special class of large‐sized gold compounds, so‐called Au nanoclusters, which lies in between traditional organogold compounds (e.g., few‐atom complexes, <1 nm) and face‐centered cubic (fcc) crystalline Au nanoparticles (typically >2 nm). The discussion is focused on the relationship between them, including the evolution from the Au???Au aurophilic interaction in AuI complexes to the direct Au? Au bond in clusters, and the structural transformation from the fcc structure in nanocrystals to non‐fcc structures in nanoclusters. Thiolate‐protected Aun(SR)m nanoclusters are used as a paradigm system. Research on such nanoclusters has achieved considerable advances in recent years and is expected to flourish in the near future, which will bring about exciting progress in both fundamental scientific research and technological applications of nanoclusters of gold and other metals. 相似文献
16.
The present study was carried out to establish the hypolipidemic effect of a phyto-steroid compound isolated from the chloroform: methanol extract of fresh mature leaves of the plant Cestrum diurnum (Solanaceae: Solanales). Change in the haematological parameters was studied in normocholesterolemic albino rats after oral administration of single dose of isolated phytosteroid (2 mg/ day) up to 15 days and compared with control rats. Application of phytosteroid fraction resulted in a significant reduction in total plasma cholesterol and free cholesterol levels. The plasma triglyceride levels also decreased significantly. A sharp increase in the HDL cholesterol level and a significant decrease in the LDL and VLDL amount were also documented. Free fatty acid level was significantly low in treated rats. 相似文献
17.
Xiaoping Wu Yaqin Chai Ruo Yuan Shihong Chen Meihe Zhang Juanjuan Zhang 《Electroanalysis》2013,25(12):2700-2706
Based on hemin‐MWCNTs nanocomposite and hemin‐catalyzed luminol‐H2O2 reaction, a sensitive electrogenerated chemiluminescence (ECL) cholesterol biosensor was proposed in this paper. Firstly, hemin‐MWCNTs was prepared via π–π stacking and modified on the surface of GCE. Subsequently, cholesterol oxidase (ChOx) was adsorbed on the modified electrode to achieve a cholesterol biosensor. Hemin‐MWCNTs nanocomposite provided the electrode with a large surface area to load ChOx, and endowed the nanostructured interface on the electrode surface to enhance the performance of biosensor. The biosensor responded to cholesterol in the linear range from 0.3 µM to 1.2 mM with a detection limit of 0.1 µM (S/N=3). 相似文献
18.
Amrita Chakraborty Ann Candice Fernandez Dr. Anirban Som Biswajit Mondal Dr. Ganapati Natarajan Dr. Ganesan Paramasivam Dr. Tanja Lahtinen Prof. Hannu Häkkinen Dr. Nonappa Prof. Thalappil Pradeep 《Angewandte Chemie (International ed. in English)》2018,57(22):6522-6526
The self‐assembled structures of atomically precise, ligand‐protected noble metal nanoclusters leading to encapsulation of plasmonic gold nanorods (GNRs) is presented. Unlike highly sophisticated DNA nanotechnology, this strategically simple hydrogen bonding‐directed self‐assembly of nanoclusters leads to octahedral nanocrystals encapsulating GNRs. Specifically, the p‐mercaptobenzoic acid (pMBA)‐protected atomically precise silver nanocluster, Na4[Ag44(pMBA)30], and pMBA‐functionalized GNRs were used. High‐resolution transmission and scanning transmission electron tomographic reconstructions suggest that the geometry of the GNR surface is responsible for directing the assembly of silver nanoclusters via H‐bonding, leading to octahedral symmetry. The use of water‐dispersible gold nanoclusters, Au≈250(pMBA)n and Au102(pMBA)44, also formed layered shells encapsulating GNRs. Such cluster assemblies on colloidal particles are a new category of precision hybrids with diverse possibilities. 相似文献
19.
Siu‐Ming Yuen Chen‐Chi M. Ma Chih‐Chun Teng Hsin‐Ho Wu Hsu‐Chiang Kuan Chin‐Lung Chiang 《Journal of Polymer Science.Polymer Physics》2008,46(5):472-482
Diglycidyl ether of bisphenol A (DGEBA)‐bridged polyorganosiloxane precursors have been prepared successfully by reacting diglycidyl ether of bisphenol A epoxy resin with 3‐aminopropyltriethoxysilane. Acid‐modified and unmodified multiwalled carbon nanotube (MWCNT) were dispersed in the diglycidyl ether of bisphenol A‐bridged polyorganosiloxane precursors and cured to prepare the carbon nanotube/diglycidyl ether of bisphenol A‐bridged polysilsesquioxane (MWCNT/DGEBA‐PSSQ) composites. The molecular motion of MWCNT/DGEBA‐PSSQ nanocomposites was studied by high‐resolution solid‐state 13C NMR. Acid‐modification can improve the affinity between MWCNT and the polymer matrix. The molecular motion of the DGEBA‐PSSQ decreased with acid‐modified MWCNT content. However, when unmodified MWCNT was used, the molecular motion of the DGEBA‐PSSQ was increased. SEM and TEM microphotographs confirm that acid‐modified MWCNT exhibits better dispersion than unmodified MWCNT in DGBEA‐PSSQ. The dynamic mechanical properties of acid‐modified MWCNT/DGBEA‐PSSQ composites are more favorable than those of unmodified MWCNT. Tg of the DGEBA‐PSSQ decreased from 174.0 °C (neat DGEBA‐PSSQ) to 159.0 °C (1 wt % unmodified MWCNT) and 156.0 °C (1 wt % acid‐modified MWCNT). The storage modulus (at 30 °C) of the DGEBA‐PSSQ increased from 1.23 × 109 Pa (neat DGEBA‐PSSQ) to 1.65 × 109 Pa (1 wt % acid‐modified MWCNT). However, when unmodified MWCNT was used, the storage modulus of the DGEBA‐PSSQ decreased to 6.88 × 108 Pa (1 wt % unmodified MWCNT). At high temperature, above 150 °C, storage modulus of nanocomposites was higher than that of neat polymer system. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 472–482, 2008 相似文献
20.
Dr. Yan Zhu Huifeng Qian Prof. Rongchao Jin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(37):11455-11462
An atomic‐level strategy is devised to gain insight into the origin of nanogold catalysis by using atomically monodisperse Aun(SR)m nanoclusters as well‐defined catalysts for styrene oxidation. The Aun(SR)m nanoclusters are emerging as a new class of gold nanocatalyst to overcome the polydispersity of conventional nanoparticle catalysts. The unique atom‐packing structure and electronic properties of Aun(SR)m nanoclusters (<2 nm) are rationalized to be responsible for their extraordinary catalytic activity observed in styrene oxidation. An interesting finding is that quantum size effects of Aun(SR)m nanoclusters, rather than the higher specific surface area, play a major role in gold‐catalyzed selective oxidation of styrene. For example, Au25(SR)18 nanoclusters (≈1 nm) are found to be particularly efficient in activating O2, which is a key step in styrene oxidation, and hence, the ultrasmall Au25 catalyst exhibits higher activity than do larger sizes. This atomic‐level strategy has allowed us to obtain an important insight into some fundamental aspects of nanogold catalysis in styrene oxidation. The ultrasmall yet robust Aun(SR)m nanoclusters are particularly promising for studying the mechanistic aspects of nanogold catalysis and for future design of better catalysts with high activity and selectivity for certain chemical processes. 相似文献