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91.
Chemical bonds of As‐implanted ZnO annealed in ozone molecular (O3) ambient were analyzed through the x‐ray photoelectron spectroscopy as a function of the etching depth. With the etching depth increased to 25 nm from surface, the peaks of Zn2p and O1s core levels shifted toward the low‐binding energy, and the bonding formation of As 3d core level gradually varied from As2O5 to As2O3. The new peaks were observed, which were posited to high‐binding energy of 4.4 eV from Zn2p and O1s core levels. Finally, the chemical bonds of As‐based oxides were found to consist of Zn(AsO3)2, As2O5, and As2O3. (© 2007 WILEY ‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Highly precise control of molecular structure for developing efficient anticancer drug delivery is challenging. Our method reported herein can satisfy the need for building novel hybrid molecule; this molecule serves as a built‐in transformer that changes its molecular configuration from a pin‐shaped arrangement to a dog bone‐shaped arrangement. This approach led to a significant increase in the efficiency of tumor inhibition. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
96.
Se Hoon Ki Somin Sin Jae-Ho Shin Young Wan Kwon Myoung Won Chae Han Sup Uhm Ku Youn Baik Eun Ha Choi 《Plasma Chemistry and Plasma Processing》2018,38(5):937-952
The studies with proteins are necessary to understand the biological effects of atmospheric pressure plasma (APP). Among proteins, those with transient metal ions play key roles in many biological events and they are very sensitive to environmental redox states. Iron-containing hemoglobin (Hb) is investigated in this study, after APP treatments under two environmental gas conditions of pure N2 and N2?+?O2 mixture. Monitoring the intensity change for absorption spectra could lead to a quantitative assessment of the effect of discharge plasma on Hb. Redox states of Hb are classified into five states including O2-bound Hb (oxy-Hb), deoxy-Hb, met-Hb, NO-bound Hb (NO-Hb), and hemichrome. Chemically generated reactive species and some scavengers are applied to understand the chemical reactions. Our experimental results confirm the complex chemical reactions of APP and suggest the possible use of Hb as a model protein for the visualization of APP biological effects. 相似文献
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The efficiency of the bromide mediated benzoylperoxide oxidation of 2° alcohols to ketones was greatly improved by the addition of water. The aqueous oxidation protocol allows also the direct use of off-the-shelf benzoylperoxide reagent without an otherwise necessary and potentially dangerous drying procedure. The oxidation of cyclopentanol, cyclohexanol, 1-phenyl-ethanol and three menthol isomers occurred in good to excellent yields. The oxidation reaction tolerated N,N-dimethylacetamide (DMA) as the solvent, which resulted in a slightly lower oxidation rate than acetonitrile. Chemoselective oxidation of vicinal diols to α-hydroxy ketones did not succeed under the aqueous organic conditions employed as over-oxidation and bromination side-reactions were observed. The impact of water content, solvent, oxidant source and type of alcohol substrates employed was investigated. 相似文献
99.
S Shah S Lee JY Verkhoturov S Tuleuova N Schweikert EA Ramanculov E Revzin A 《Langmuir : the ACS journal of surfaces and colloids》2008,24(13):6837-6844
This paper describes a novel approach of controlling cell-surface interactions through an electrochemical "switching" of biointerfacial properties of optically transparent microelectrodes. The indium tin oxide (ITO) microelectrodes, fabricated on glass substrates, were modified with poly(ethylene glycol) (PEG) silane to make glass and ITO regions resistant to protein and cell adhesion. Cyclic voltammetry, with potassium ferricyanide serving as a redox reporter molecule, was used to monitor electron transfer across the electrolyte-ITO interface. PEG silane modification of ITO correlated with diminished electron transfer, judged by the disappearance of ferricyanide redox activity. Importantly, application of reductive potential (-1.4 V vs Ag/AgCl reference) corresponded with reappearance of typical ferricyanide redox peaks, thus pointing to desorption of an insulating PEG silane layer. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) characterization of the silanized ITO surfaces after electrical stimulation indicated complete removal of the silane layer. Significantly, electrical stimulation allowed to "switch" chosen electrodes from nonfouling to protein-adhesive while leaving other ITO and glass regions protected by a nonfouling PEG silane layer. The spatial and temporal control of biointerfacial properties afforded by our approach was utilized to micropattern proteins and cells and to construct micropatterned co-cultures. In the future, control of the biointerfacial properties afforded by this novel approach may allow the organization of multiple cell types into precise geometric configurations in order to create better in vitro mimics of cellular complexity of the native tissues. 相似文献
100.
Lee JY Shah SS Zimmer CC Liu GY Revzin A 《Langmuir : the ACS journal of surfaces and colloids》2008,24(5):2232-2239
Protein microarrays are rapidly emerging as valuable tools in creating combinatorial cell culture systems where inducers of cellular differentiation can be identified in a rapid and multiplexed fashion. In the present study, protein microarraying was combined with photoresist lithography to enable printing of extracellular matrix (ECM) protein arrays while precisely controlling "on-the-spot" cell-cell interactions. In this surface engineering approach, the micropatterned photoresist layer formed on a glass substrate served as a temporary stencil during the microarray printing, defining the micrometer-scale dimensions and the geometry of the cell-adhesion domains within the printed protein spots. After removal of the photoresist, the glass substrates contained micrometer-scale cell-adhesive regions that were encoded within 300 or 500 microm diameter protein domains. Fluorescence microscopy and atomic force microscopy (AFM) were employed to characterize protein micropatterns. When incubated with micropatterned surfaces, hepatic (HepG2) cells attached on 300 or 500 mum diameter protein spots; however, the extent of cell-cell contacts within each spot varied in accordance with dimensions of the photoresist stencil, from single cells attaching on 30 microm diameter features to multicell clusters residing on 100 or 200 microm diameter regions. Importantly, the photoresist removal process was shown to have no detrimental effects on the ability of several ECM proteins (collagens I, II, and IV and laminin) to support functional hepatic cultures. The micropatterning approach described here allows for a small cell population seeded onto a single cell culture substrate to be exposed to multiple scenarios of cell-cell and cell-surface interactions in parallel. This technology will be particularly useful for high-throughput screening of biological stimuli required for tissue specification of stem cells or for maintenance of differentiated phenotype in scarce primary cells. 相似文献