The Experts below are selected from a list of 11076 Experts worldwide ranked by ideXlab platform
Meilin Liu - One of the best experts on this subject based on the ideXlab platform.
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Carbon fiber paper supported hybrid nanonet/nanoflower nickel oxide electrodes for high-performance pseudo-capacitors
Journal of Materials Chemistry, 2013Co-Authors: Shuang Cheng, Lei Yang, Wei Lin, Dongchang Chen, Ching-ping Wong, Liang Huang, Yong Liu, Meilin LiuAbstract:A composite electrode consisting of hybrid nanonet/nanoflower NiO deposited on carbon fiber paper scaffolds demonstrates a much-improved areal capacitance (0.93 F cm−2) while maintaining high rate capability and excellent cycling life. These performance characteristics are attributed to the unique electrode architecture and the nanostructures of NiO. While the nanonet NiO with a high surface area greatly facilitates the redox reactions for charge storage, the porous Nanoflowers further extend the active sites for the redox reactions, leading to fast Faradic reactions for efficient energy storage.
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carbon fiber paper supported hybrid nanonet nanoflower nickel oxide electrodes for high performance pseudo capacitors
Journal of Materials Chemistry, 2013Co-Authors: Shuang Cheng, Lei Yang, Wei Lin, Dongchang Chen, Ching-ping Wong, Meilin Liu, Liang Huang, Yong LiuAbstract:A composite electrode consisting of hybrid nanonet/nanoflower NiO deposited on carbon fiber paper scaffolds demonstrates a much-improved areal capacitance (0.93 F cm−2) while maintaining high rate capability and excellent cycling life. These performance characteristics are attributed to the unique electrode architecture and the nanostructures of NiO. While the nanonet NiO with a high surface area greatly facilitates the redox reactions for charge storage, the porous Nanoflowers further extend the active sites for the redox reactions, leading to fast Faradic reactions for efficient energy storage.
Yi Wang - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and continuous catalytic application of alkaline protease Nanoflowers–PVA composite hydrogel
Catalysis Communications, 2018Co-Authors: Haiyang Zhang, Xu Fei, Jing Tian, Hui Zhi, Kang Wang, Yi WangAbstract:Abstract This paper reports a facile approach for the synthesis of alkaline protease Nanoflowers–poly(vinyl alcohol) (PVA) composite hydrogel (NPCH) from alkaline protease–Cu3(PO4)2·3H2O Nanoflowers and PVA hydrogel through freezing–thawing. During continuous catalytic application, the PVA hydrogel network protected alkaline protease–Cu3(PO4)2·3H2O Nanoflowers from damage and helped maintain enzymatic activity at high levels. The enzyme that had been immobilized in Nanoflowers and NPCH demonstrated 1027% and 605% higher activity than the free alkaline protease derived from Bacillus licheniformis. When used in cyclic catalysis, NPCH exhibited better reusability than Nanoflowers and was easily separated from the product.
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The influence of synthesis conditions on enzymatic activity of enzyme-inorganic hybrid Nanoflowers
Journal of Molecular Catalysis B: Enzymatic, 2016Co-Authors: Xu Fei, Jing Tian, Xiuying Wang, Liwen Liang, Yi WangAbstract:Abstract In this work, we synthesized hierarchical flower-like structures by using lipase and papain as organic components and Cu3(PO4)2·3H2O as the inorganic component. These hybrid-nanoflower structures were confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. By changing the synthesis conditions, including enzyme concentration, pH, and temperature for the Nanoflowers, we can control the morphology and enzymatic activity of nanoflower. Enzyme concentration and synthesis temperature affect nanoflower size and petal density, whereas pH influences petal density only. Furthermore, we found the optimal conditions to improve the enzymatic activity of lipase-Cu3(PO4)2·3H2O and papain-Cu3(PO4)2·3H2O Nanoflowers. The appropriate enzyme content, flower size, and flower density were the critical factors for high enzymatic activity.
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self assembled enzyme inorganic hybrid Nanoflowers and their application to enzyme purification
Colloids and Surfaces B: Biointerfaces, 2015Co-Authors: Xu Fei, Jing Tian, Xiuying Wang, Yi WangAbstract:We report a novel method to synthesize organic–inorganic Nanoflowers for crude soybean peroxidase (SBP) purification. A hierarchical flower-like spherical structure with hundreds of nanopetals was self-assembled by using crude SBP as the organic component and Cu3(PO4)2·3H2O as the inorganic component. The structure of the hybrid Nanoflowers was confirmed by Fourier-transform infrared spectroscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy, and the enzymatic activity of SBP embedded in the hybrid Nanoflowers was evaluated using guaiacol as substrate. Compared with free crude SBP in solution, SBP embedded in hybrid Nanoflowers exhibited enhanced enzymatic activity (∼446%). The hybrid Nanoflowers also exhibited excellent reusability and reproducibility during cycle analysis. These results demonstrate that synthesis of hybrid Nanoflowers is an effective enzyme purification strategy.
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Self-assembled enzyme–inorganic hybrid Nanoflowers and their application to enzyme purification
Colloids and Surfaces B: Biointerfaces, 2015Co-Authors: Xu Fei, Jing Tian, Xiuying Wang, Yi WangAbstract:We report a novel method to synthesize organic–inorganic Nanoflowers for crude soybean peroxidase (SBP) purification. A hierarchical flower-like spherical structure with hundreds of nanopetals was self-assembled by using crude SBP as the organic component and Cu3(PO4)2·3H2O as the inorganic component. The structure of the hybrid Nanoflowers was confirmed by Fourier-transform infrared spectroscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy, and the enzymatic activity of SBP embedded in the hybrid Nanoflowers was evaluated using guaiacol as substrate. Compared with free crude SBP in solution, SBP embedded in hybrid Nanoflowers exhibited enhanced enzymatic activity (∼446%). The hybrid Nanoflowers also exhibited excellent reusability and reproducibility during cycle analysis. These results demonstrate that synthesis of hybrid Nanoflowers is an effective enzyme purification strategy.
Jeongwoo Choi - One of the best experts on this subject based on the ideXlab platform.
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detection of effect of chemotherapeutic agents to cancer cells on gold nanoflower patterned substrate using surface enhanced raman scattering and cyclic voltammetry
Biosensors and Bioelectronics, 2010Co-Authors: Waleed Ahmed Elsaid, Taehyung Kim, Hyuncheol Kim, Jeongwoo ChoiAbstract:In vitro assays have generally been carried out for cytological diagnosis and for evaluation of the cytotoxic effect of chemotherapeutic agents as an alternative to animal experiments. In this study, a method for fabrication and application of a gold nanoflower array on an ITO substrate for evaluation of the effect of chemotherapeutic agents on cancer cell behavior by the surface-enhanced Raman scattering (SERS) analysis, as well as the electrochemical detection was described. Due to the increased sensitivity provided by gold nanoflower substrates, the effect of chemotherapeutic agents at low concentration level was successfully detected based on SERS technique. This substrate was found to give enhanced Raman spectra with high surface plasmon field in the near infrared (NIR) spectral range, which minimize fluorescence interference and photo-toxicity. Cyclic voltammetry (CV) was further performed for confirmation of results obtained by SERS assay and showed increased intensity of current peaks for various concentrations at low levels. The developed Au Nanoflowers modified ITO substrates developed in this study could be used as a simultaneous SERS and CV substrate to determine the effects of chemotherapeutic agents on cancer cells.
Kaushik Chakrabarti - One of the best experts on this subject based on the ideXlab platform.
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Template free synthesis of SnO2 nanoflower arrays on Sn foil
CrystEngComm, 2012Co-Authors: Sirshendu Ghosh, Kajari Das, Kaushik ChakrabartiAbstract:The well aligned poppy-flower-like SnO2 nanoflower array on Sn-foil was successfully prepared by a simple solvothermal method without using any template or catalyst. The mixed solvent of aqueous sodium hydroxide and hydrazine hydrate plays a significant role for obtaining the crystalline pure SnO2 nanoflower array. Each petal of the nanoflower consists of the (110) plane of SnO2. The growth of the SnO2 Nanoflowers has been described by the formation of layered Sn-hydrazine complexes. The surface defects and the oxygen vacancies of the SnO2 hierarchical Nanoflowers are identified by Raman and electron paramagnetic resonance (EPR) spectroscopy and are analyzed in detail by steady state and time resolved photoluminescence spectra.
Richard N Zare - One of the best experts on this subject based on the ideXlab platform.
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rapid detection of phenol using a membrane containing laccase Nanoflowers
Chemistry-an Asian Journal, 2013Co-Authors: Lin Zhu, Lu Gong, Yifei Zhang, Rui Wang, Zheng Liu, Richard N ZareAbstract:With the rapid development of nanoscience and nanotechnology, nanostructured biocatalysts that take the advantage of nanomaterials in terms of both functional and structural availability have offered new opportunities for improving biological functions of enzymes and expanding applications in areas such as biosensors, bioanalytical devices, and industrial biocatalysis. Recently, we reported a method of preparing protein–inorganic hybrid nanostructures with flower-like shapes, which have shown much greater activities than free enzymes and most of the reported immobilized enzymes. To bring this appealing catalyst into practical use, however, an effective accommodation of these high-performance enzyme catalysts is required. One way is to weakly attach these enzyme Nanoflowers to porous materials by physical adsorption. Recently, Krieg et al. reported the fabrication of a supramolecular membrane by noncovalent modification of a commercial membrane, which suggests the possibility of fabricating functional filtration membranes by a simple post-modification procedure, thus enabling many new and interesting applications. It thus came to our mind to fabricate a membrane incorporating enzyme Nanoflowers for the rapid detection of hazardous compounds through visualization of the catalyzed product. Owing to their high toxicity even at a low concentration, phenols are listed as major toxic pollutants by the Environmental Protection Agency of the USA and other countries. Sensitive detection of phenolic compounds has been well established using instrumental analysis such as liquid chromatography. However, these methods usually require sophisticated instrumentation and a multistep procedure, making them less convenient for rapid and on-site detection. The present study started by the fabrication of an enzyme nanoflower incorporated into a membrane. As shown in Figure 1, a suspension of laccase–inorganic hybrid Nanoflowers, which have a high activity (ca. 200% that of free laccase) for phenol oxidization, as we observed previously, was injected into a commercial disposable syringe filter equipped with a cellulose acetate membrane (pore size 0.2 mm). This procedure thus deposited enzyme Nanoflowers with an average size of 4 mm onto the membrane. Then the aqueous sample containing phenol was mixed with an aqueous solution of 4-aminoantipyrine and was passed through the membrane with incorporated laccase Nanoflowers, causing oxidative coupling of phenol with 4-aminoantipyrine to form an antipyrine dye that has an absorption maximum at 495 nm. This procedure allowed rapid analysis by a UV/ Vis spectrophotometer or by the naked eye. Finally, pure water was injected into the filter to remove unreacted reagents and the reaction products, followed by drying the membrane in air for the next use. For the preparation of laccase–copper phosphate Nanoflowers, typically, 0.8 mm aqueous CuSO4 was added to phosphate buffered saline (PBS) containing 0.1 mgmL 1 laccase at pH 7.4 and 25 8C. After three days, the precipitate of laccase Nanoflowers appeared with porous, flower-like structures. Scanning electron microscopy (SEM) images of the Nanoflowers are presented in Figure 2a,b, from which the average diameter of the laccase Nanoflowers was determined [a] L. Zhu, L. Gong, Y. Zhang, R. Wang, Prof. J. Ge, Prof. Z. Liu Department of Chemical Engineering, Tsinghua University Beijing 100084 (China) E-mail : junge@mail.tsinghua.edu.cn liuzheng@mail.tsinghua.edu.cn [b] Prof. R. N. Zare Department of Chemistry, Stanford University Stanford, CA 94305-5080 (USA) E-mail : zare@stanford.edu [] These authors contributed equally to this work. Figure 1. Fabrication, use, washing, and reuse of the membrane with incorporated laccase Nanoflowers. Phenol and ortho-, meta-, and para-substituted phenols carrying carboxy, halogen, methoxy, or sulfonic acid groups react with 4-aminoantipyrine to form colored compounds, which can then be readily detected.
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Protein-inorganic hybrid Nanoflowers
Nature Nanotechnology, 2012Co-Authors: Jun Ge, Jiandu Lei, Richard N ZareAbstract:Flower-shaped inorganic nanocrystals have been used for applications in catalysis and analytical science, but so far there have been no reports of 'Nanoflowers' made of organic components. Here, we report a method for creating hybrid organic-inorganic Nanoflowers using copper (II) ions as the inorganic component and various proteins as the organic component. The protein molecules form complexes with the copper ions, and these complexes become nucleation sites for primary crystals of copper phosphate. Interaction between the protein and copper ions then leads to the growth of micrometre-sized particles that have nanoscale features and that are shaped like flower petals. When an enzyme is used as the protein component of the hybrid nanoflower, it exhibits enhanced enzymatic activity and stability compared with the free enzyme. This is attributed to the high surface area and confinement of the enzymes in the Nanoflowers.
