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排序方式: 共有755条查询结果,搜索用时 93 毫秒
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Marie Leroy Michel Lafleur Michèle Auger Gaétan Laroche Roxane Pouliot 《Analytical and bioanalytical chemistry》2013,405(27):8709-8718
The skin acts mainly as a protective barrier from the external environment, thanks to the stratum corneum which is the outermost layer of the skin. As in vitro tests on skin are essential to elaborate new drugs, the development of skin models closer to reality becomes essential. It is now possible to produce in vitro human skin substitutes through tissue engineering by using the self-assembly method developed by the Laboratoire d’Organogénèse Expérimentale. In the present work, infrared microspectroscopy imaging analyses were performed to get in-depth morpho-spectral characterization of the three characteristic layers of human skin substitutes and normal human skin, namely the stratum corneum, living epidermis, and dermis. An infrared spectral analysis of the skin is a powerful tool to gain information on the order and conformation of the lipid chains and the secondary structure of proteins. On one hand, the symmetric stretching mode of the lipid methylene groups (2,850 cm?1) is sensitive to the acyl chain conformational order. The evolution profile of the frequency of this vibrational mode throughout the epidermis suggests that lipids in the stratum corneum are more ordered than those in the living epidermis. On the other hand, the frequencies of the infrared components underneath the envelop of the amide I band provide information about the overall protein conformation. The analysis of this mode establishes that the proteins essentially adopt an α-helix conformation in the epidermis, probably associated with the presence of keratin, while modifications of the protein content are observed in the dermis (extracellular matrix made of collagen). Finally, the lipid organization, as well as the protein composition in the different layers, is similar for human skin substitutes and normal human skin, confirming that the substitutes reproduce essential features of real skin and are appropriate biomimetics. 相似文献
44.
Kristjan S. Gudmundsson Jack M. Hinkley Michael S. Brieger John C. Drach Leroy B. Townsend 《合成通讯》2013,43(5):861-870
An efficient large scale synthesis of 2-amino-4-chloropyridine (3) has been achieved through a modification of existing literature procedures. Compound 3 was used to prepare the previously unreported 2-amino-4,5-dichloropyridine (4). The known 2-amino-3,4-dichloropyridine (5) and 2-amino-3,4,5-trichloropyridine (6) were prepared from 3 by new routes and in higher yields than previously reported. 相似文献
45.
Dr. Laia Vilà‐Nadal Dr. Scott G. Mitchell Dr. Stanislav Markov Dr. Christoph Busche Dr. Vihar Georgiev Prof. Asen Asenov Prof. Leroy Cronin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(49):16502-16511
We explore the concept that the incorporation of polyoxometalates (POMs) into complementary metal oxide semiconductor (CMOS) technologies could offer a fundamentally better way to design and engineer new types of data storage devices, due to the enhanced electronic complementarity with SiO2, high redox potentials, and multiple redox states accessible to polyoxometalate clusters. To explore this we constructed a custom‐built simulation domain bridge. Connecting DFT, for the quantum mechanical modelling part, and mesoscopic device modelling, confirms the theoretical basis for the proposed advantages of POMs in non‐volatile molecular memories (NVMM) or flash‐RAM. 相似文献
46.
Ross S. Winter Dr. Jun Yan Dr. Christoph Busche Dr. Jennifer S. Mathieson Dr. Alessandro Prescimone Prof. Euan K. Brechin Dr. De‐Liang Long Prof. Leroy Cronin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(9):2976-2981
Two near isomeric clusters containing a novel {Mn8W4} Keggin cluster within a [W36Mn10Si4O136(OH)4(H2O)8]24? cluster are reported: K10Li14 [W36Si4O136MnII10(OH)4(H2O)8] ( 1 ) and K10Li13.5Mn0.25[W36Si4O136MnII10(OH)4(H2O)8] ( 1′ ). Bulk characterization of the clusters has been carried out by single crystal X‐ray structure analysis, ICP‐MS, TGA, ESI‐MS, CV and SQUID‐magnetometer analysis. X‐ray analysis revealed that 1′ has eight positions within the central Keggin core that were disordered W/Mn whereas 1 contained no such disorder. This subtle difference is due to a differences is how the two clusters assemble and recrystallize from the same mother liquor and represents a new type of isomerism. The rapid recrystallization process was captured via digital microscopy and this uncovered two “intermediate” types of crystal which formed temporarily and provided nucleation sites for the final clusters to assemble. The intermediates were investigated by single crystal X‐ray analysis and revealed to be novel clusters K4Li22[W36Si4Mn7O136(H2O)8]?56 H2O ( 2 ) and Mn2K8Li14[W36Si4Mn7O136(H2O)8]?45 H2O ( 3 ). The intermediate clusters contained different yet related building blocks to the final clusters which allowed for the postulation of a mechanism of assembly. This demonstrates a rare example where the use X‐ray crystallography directly facilitated understanding the means by which a POM assembled. 相似文献
47.
Dr. Thomas Ehrenschwender Dr. Wolfgang Schmucker Christian Wellner Dipl.‐Chem. Timo Augenstein Dr. Patrick Carl Dr. Jeffrey Harmer Prof. Dr. Frank Breher Prof. Dr. Hans‐Achim Wagenknecht 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(37):12547-12552
A new C‐nucleoside structurally based on the hydroxyquinoline ligand was synthesized that is able to form stable pairs in DNA in both the absence and the presence of metal ions. The interactions between the metal centers in adjacent CuII‐mediated base pairs in DNA were probed by electron paramagnetic resonance (EPR) spectroscopy. The metal–metal distance falls into the range of previously reported values. Fluorescence studies with a donor–DNA–acceptor system indicate that photoinduced charge‐transfer processes across these metal‐ion‐mediated base pairs in DNA occur more efficiently than over natural base pairs. 相似文献
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49.
Dr. Abdulghani Ismail Dr. Silvia Voci Lucie Descamps Dr. Arnaud Buhot Prof. Dr. Neso Sojic Dr. Loïc Leroy Dr. Aurélie Bouchet-Spinelli 《Chemphyschem》2021,22(11):1094-1100
This work depicts the original combination of electrochemiluminescence (ECL) and bipolar electrochemistry (BPE) to map in real-time the oxidation of silicon in microchannels. We fabricated model silicon-PDMS microfluidic chips, optionally containing a restriction, and monitored the evolution of the surface reactivity using ECL. BPE was used to remotely promote ECL at the silicon surface inside microfluidic channels. The effects of the fluidic design, the applied potential and the resistance of the channel (controlled by the fluidic configuration) on the silicon polarization and oxide formation were investigated. A potential difference down to 6 V was sufficient to induce ECL, which is two orders of magnitude less than in classical BPE configurations. Increasing the resistance of the channel led to an increase in the current passing through the silicon and boosted the intensity of ECL signals. Finally, the possibility of achieving electrochemical reactions at predetermined locations on the microfluidic chip was investigated using a patterning of the silicon oxide surface by etched micrometric squares. This ECL imaging approach opens exciting perspectives for the precise understanding and implementation of electrochemical functionalization on passivating materials. In addition, it may help the development and the design of fully integrated microfluidic biochips paving the way for development of original bioanalytical applications. 相似文献
50.
Time‐Resolved Assembly of Cluster‐in‐Cluster {Ag12}‐in‐{W76} Polyoxometalates under Supramolecular Control 下载免费PDF全文
Caihong Zhan Jamie M. Cameron Jing Gao Jamie W. Purcell De‐Liang Long Leroy Cronin 《Angewandte Chemie (International ed. in English)》2014,53(39):10362-10366
We report the time‐resolved supramolecular assembly of a series of nanoscale polyoxometalate clusters (from the same one‐pot reaction) of the form: [H(10+m)Ag18Cl(Te3W38O134)2]n, where n=1 and m=0 for compound 1 (after 4 days), n=2 and m=3 for compound 2 (after 10 days), and n=∞ and m=5 for compound 3 (after 14 days). The reaction is based upon the self‐organization of two {Te3W38} units around a single chloride template and the formation of a {Ag12} cluster, giving a {Ag12}‐in‐{W76} cluster‐in‐cluster in compound 1 , which further aggregates to cluster compounds 2 and 3 by supramolecular Ag‐POM interactions. The proposed mechanism for the formation of the clusters has been studied by ESI‐MS. Further, control experiments demonstrate the crucial role that TeO32?, Cl?, and Ag+ play in the self‐assembly of compounds 1 – 3 . 相似文献