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1.
High–throughput‐screening (HTS) tools and methods are used more and more, especially in industry, in the search for new, selective organometallic catalysts. In most cases, the approach is, in essence, empirical, and the strategy is to increase the number of experiments that can be run at a given place in a given time. Highly miniaturized, parallel reaction setups have been implemented for the rapid assessment of whether novel catalysts resulting from the structural amplification of a basic framework are “good” or “bad” with respect to the properties of interest, and, depending on the response, worthy of a subsequent, more‐careful evaluation. In this article, we demonstrate that it is possible to utilize these state‐of‐the‐art HTS platforms with a different strategy: the rapid generation of reliable kinetic data for mechanistic studies in view of a thorough understanding and rational catalyst design. Ziegler–Natta‐type catalytic olefin polymerization will be used throughout as an example.

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2.
Libraries with varying composition and exposure time were developed to enable high‐throughput analysis of conversion using FTIR spectroscopy. This technique was demonstrated by measuring viscosity and backbone chain structure effects using four monomers: DPGDA, TEGDA, bisphenol‐A‐glycidyl diacrylate and ethoxylated bisphenol‐A diacrylate. DPGDA has equivalent viscosity and double bond concentration with a shorter backbone chain length as compared to TEGDA. The ultimate conversion of TEGDA copolymerizations as compared to equivalent DPGDA copolymerizations is lowered from 15 to 5% due to differences in crosslink space chemistry and glass transition temperatures of the copolymer formulation.

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3.
A Ziegler‐Natta/metallocene hybrid catalyst was produced and utilized in the polymerization of ethylene with the aim of producing bimodal polyethylene. The MgCl2 adduct was prepared by a melt quenching method and Cp2ZrCl2 and TiCl4 catalysts were loaded, respectively, after treating the surface with TiBAl. The polymerization kinetics involved an induction period, followed by fragmentation and expansion of particles. SEM micrographs revealed that the spherical morphology was retained through the initial mild reaction conditions of induction period. The polymers produced showed bimodal molecular weight distribution patterns, suggesting that both components of the hybrid catalyst were active over the support.

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4.
We use photothermal microscopy to detect and image individual gold nanoparticles that are either embedded in a polymer film or immobilized in an aqueous environment. Reducing the numerical aperture of the detection optics allows us to achieve a 200‐fold‐enlarged detection volume while still retaining sufficient detectivity. We characterize the capabilities of this approach for the detection of gold colloids with a diameter of 20 nm, with emphasis on practical aspects that are important for high‐throughput‐screening applications. The extended detection volume in combination with the stability of the photothermal signal are major advantages compared to fluorescence‐based approaches, which are limited by photoblinking and photobleaching. Careful consideration is given to the trade‐off between the maximum increase in local temperature that can be tolerated by a biological specimen and the minimum integration time needed to reliably determine whether a given volume contains a target species. We find that our approach has the potential to increase the detection‐limited flow rate (i.e. the limit given by the detection volume divided by the minimum detection time) by two to three orders of magnitude.  相似文献   

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Gangliosides are important signaling molecules in the cell membrane and are processed by several enzymes. Deficiencies in these enzymes can cause human lysosomal storage diseases. Building an understanding of the pathways of glycosphingolipid catabolism requires methods for the analysis of these enzymatic activities A GM3‐derived FRET probe was synthesized chemoenzymatically for the detection and quantitation of a range of ganglioside‐degrading enzymes, both in cell lysates and in living cells. This is the first substrate that enables the ratiometric fluorogenic assay of sphingolipid ceramide N‐deacylase and endoglycoceramidase and can detect and localize neuraminidase activity in living cells. It is therefore a valuable tool for building a better understanding of membrane‐confined enzymology. It also enables the robust and reliable assay of ganglioside‐degrading enzymes in a microtiter plate, thus opening the door to screening for novel or engineered biocatalysts or for new inhibitors.  相似文献   

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Increasing evidence shows that activated mesenchymal migration is a key process of the metastatic cascade. Cancer cells usually gain such migratory capability through an epithelial‐to‐mesenchymal transition. Herein we present a high‐throughput microfluidic device with 3120 microchambers to specifically monitor mesenchymal migration. Through imaging of the whole chip and statistical analysis, we can evaluate the two key factors of velocity and percentage related to cell migratory capacity at different cell densities in culture. We also used the device to screen antimetastatic drugs for their inhibition of mesenchymal migration and prevention of metastatic malignancy. This device will provide an excellent platform for biologists to gain a better understanding of cancer metastasis.  相似文献   

10.
Currently laboratory automation is a rapidly growing field of interest in chemical process research and development. The idea of using automated and parallel methods for the optimization of chemical processes was initiated by the extensive implementation of combinatorial techniques in medicinal chemistry. The techniques applied involve all methods and concepts aimed at dramatically increasing the output of research by extensive use of automation, parallelization and miniaturization, fast analysis, advanced data handling and by efficient automated planning, scheduling and tracking. In this paper, the “Combi” or high‐throughput experimentation approach consists of the integration of parallel experimentation with four key modeling and simulation methodologies, modeling, multivariate statistics, statistical design of experimentation and empirical model generation.

Integrated automated liquid and solid handling.  相似文献   


11.
Fluorescent sensors are powerful tools for visualizing cellular molecular dynamics. We present a high‐throughput screening system, designated hybrid‐type fluorescence indicator development (HyFInD), to identify optimal position‐specific fluorophore labeling in hybrid‐type sensors consisting of combinations of ligand‐binding protein mutants with small molecular fluorophores. We screened sensors for glutamate among hybrid molecules obtained by the reaction of four cysteine‐reactive fluorescence probes with a set of cysteine‐scanning mutants of the 274 amino acid S1S2 domain of AMPA‐type glutamate receptor GluA2 subunit. HyFInD identified a glutamate‐responsive probe (enhanced glutamate optical sensor: eEOS) with a dynamic range >2400 %, good photostability, and high selectivity. When eEOS was specifically tethered to neuronal surfaces, it reliably visualized the spatiotemporal dynamics of glutamate release at single synapses, revealing synapse‐to‐synapse heterogeneity of short‐term plasticity.  相似文献   

12.
Optimising synthetic conversions and assessing catalyst performance is a tedious and laborious endeavour. Herein, we present an automated alternative to the commonly applied sequential approaches that are used to increase catalyst discovery process efficiencies by increasing the number of entities that can be tested. This new approach combines conversion of the reactants and determination of product formation into a single comprehensive reaction detection system that can be operated with minimal catalyst and reactant consumption. With this approach, rudimentary reaction conditions can be quickly optimised and the same system can then be used to screen for the optimal homogenous catalyst in a selected solution‐phase synthetic conversion. The system, which is composed of standard HPLC components, can be used to screen catalyst libraries at a repetition rate of five minutes and can be run unsupervised. The sensitive mass spectrometric detection that is implemented in the reaction detection methodology can be used for the simultaneous monitoring of reactants, catalysts and product ions. In the experiments, the three‐component reaction that gives a substituted 2‐imidazoline was optimised. Afterwards, the same method was used to assess a library of ferrocene‐based Lewis acid catalysts for performance in the aforementioned conversion in six different solvents. We demonstrate the feasibility of using this methodology to directly compare the performance results obtained in different solvents by calibrating the solvent‐specific MS responses.  相似文献   

13.
Combinatorial libraries of segmented polyurethaneurea with gradients in curing temperature were prepared and characterized using a novel high‐throughput mechanical instrument. Stress/strain profiles were taken at different temperature positions on the libraries, and a structure/property relationship between microstructure and mechanical properties was established by correlating the measured strength and strain at break to high‐throughput AFM and FT‐IR measurements on the same library. These results demonstrate the feasibility of rapid and accurate screening of mechanical properties, and their correlation to structure, by using gradient combinatorial polymer libraries.

Impact energy/thickness and elongation at break versus cure T for a T‐gradient SPUU library.  相似文献   


14.
Appropriate surface attachment is essential for growing embryonic stem (ES) cells in an undifferentiated state. It is challenging to identify the optimal surface chemistry of the substrata for ES cell attachment and maintenance. Using a rapid, high‐throughput polymerization and screening platform with a comprehensive library of 66 monomer‐grafted membrane surfaces, the optimal substrate, N‐[3‐(dimethylamino)propyl] methacrylamide (DMAPMA) has been identified to support strong attachment, high expansion capacity, and long‐term self‐renewal of ES cells (up to 7 passages). This monomer‐based, chemically defined, scalable, sustainable, relatively inexpensive, covalently grafted, and controllable polymeric substrate provides a new opportunity to manipulate surface chemistry for pluripotent stem culture.

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15.
Summary: An approach for the high‐throughput preparation and characterisation of aqueous pigment dispersions is described and evaluated. The use of ultrasonication as a rapid technique for dispersing pigments using polymeric dispersants was developed. The results are comparable to those obtained using time‐intensive conventional high‐energy ball mill processing. The quality of the pigment dispersion was evaluated in a high‐throughput fashion using digital image analysis and the results correlated with particle sizes, determined by photo‐correlation spectroscopy.

Cuvettes containing dispersions of varying particle size.  相似文献   


16.
Arylhalides are important building blocks in many fine chemicals, pharmaceuticals and agrochemicals, and there has been increasing interest in the development of more “green” halogenation methods based on enzyme catalysis. However, the screening and development of new enzymes for biohalogenation has been hampered by a lack of high‐throughput screening methods. Described herein is the development of a colorimetric assay for detecting both chemical and enzymatic arylamine halogenation reactions in an aqueous environment. The assay is based on the unique UV/Vis spectrum created by the formation of an ortho‐benzoquinone‐amine adduct, which is produced by the peroxidase‐catalysed benzoquinone generation, followed by Michael addition of either a halogenated or non‐halogenated arylamine. This assay is sensitive, rapid and amenable to high‐throughput screening platforms. We have also shown this assay to be easily coupled to a flavin‐dependent halogenase, which currently lacks any convenient colorimetric assay, in a “one‐pot” workflow.  相似文献   

17.
Combinatorial techniques, parallel experimentation and high‐throughput methods represent a very promising approach in order to speed up the preparation and investigation of new polymeric materials: a large variety of parameters can be screened simultaneously resulting in new structure/property relationships. The field of polymer research seems to be perfectly suited for parallel and combinatorial methods due to the fact that many parameters can be varied during synthesis, processing, blending as well as compounding. In addition, numerous important parameters have to be investigated, such as molecular weight, polydispersity, viscosity, hardness, stiffness and other application‐specific properties. A number of corresponding high‐throughput techniques have been developed in the last few years and their introduction into the commercial market further boosted the development. These combinatorial approaches can reduce the time‐to‐market for new polymeric materials drastically compared to traditional approaches and allow a much more detailed understanding of polymers from the macroscopic to the nanoscopic scale. Here we provide an overview of the present status of combinatorial and parallel polymer synthesis and high‐throughput screening.

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18.
The kinetics of ethene polymerization catalyzed by Cp2ZrCl2 /MAO is studied. A detailed look is taken at the different kinetic models used to describe the polymerization process. Also, a new model was developed on the basis of previous work. The new model takes both the active‐sites mechanism and the reactivation effect of MAO into account. Better agreement between the experimental data and the fitting profile was achieved by applying the new model, when compared with the results from older models. A plausible mechanism of polymerization is outlined.  相似文献   

19.
A new approach for the estimation of kinetic rate constants in olefin polymerization using metallocene catalysts is presented. The polymerization rate has been modeled using the method of moments. An ANN has been used and trained to behave like the mathematical model developed before, so that it gets polymerization rate at different reaction times and predicts reaction rate constants. The network was trained using modeling results in desired operational window. The polymerization rates were normalized to make the network work independent of operational conditions. The model has also been applied to real polymerization rate data and the predictions were satisfactory. This model is specially useful in comparing different new metallocene catalysts.

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20.
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