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Steinhoff A, Höltzel A, Tallarek U. The Solvation Shell of Small Solutes in Aqueous-Organic Solvent Mixtures and Its Implications for Reversed-Phase Liquid Chromatography. J Phys Chem B 2023; 127:10052-10066. [PMID: 37943096 DOI: 10.1021/acs.jpcb.3c05492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
Reversed-phase liquid chromatography (RPLC) operates with water-organic solvent (W-OS) mobile phases where preferential solvation (PS) of solutes is likely. To investigate the relevance of the solute solvation shell in the mobile phase for RPLC retention, we combine data from molecular dynamics simulations of small, neutral solutes (six analytes and two dead time markers) in W-methanol (MeOH) and W-acetonitrile (ACN) mixtures with corresponding retention data obtained on an RPLC column over a wide range of W/OS ratios. Data derived from Kirkwood-Buff integrals show PS by the OS for analytes vs low or negative PS for dead time markers. W-ACN mixtures generate a higher amount of PS than W-MeOH mixtures, which contributes to the higher eluent strength of ACN in RPLC. Difference spatial distribution functions reveal anisotropic solvation shells with OS excess at hydrocarbon elements and W excess at functional groups, predicting that retention by the hydrophobic stationary phase is favored by hydrocarbon elements and limited by functional groups. Analysis of solute-solvent hydrogen bonds pinpoints the hydrogen-bond requirements toward W as the retention-limiting factor. The relation between the solute solvation shell and retention confirms the importance of W-OS and solute-W hydrogen bonding for RPLC retention.
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Affiliation(s)
- Andreas Steinhoff
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, Marburg 35032, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, Marburg 35032, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, Marburg 35032, Germany
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2
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Steinhoff A, Höltzel A, Trebel N, Tallarek U. Mobile-Phase Contributions to Organic-Solvent Excess Adsorption and Surface Diffusion in Reversed-Phase Liquid Chromatography. J Phys Chem B 2022; 126:10554-10568. [PMID: 36469753 DOI: 10.1021/acs.jpcb.2c06871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Fast transport of retained analytes in reversed-phase liquid chromatography occurs through surface diffusion in the organic-solvent (OS)-enriched interfacial "ditch" region between the hydrophobic stationary phase and the water (W)-OS mobile phase. Through molecular dynamics simulations that recover the OS excess adsorption isotherms of a typical C18-stationary phase for methanol and acetonitrile, we explore the relation between OS properties, OS excess adsorption, and surface diffusion. The emerging molecular-level picture attributes the mobile-phase contribution to surface diffusion to the hydrogen-bond capability and the eluting power of the OS. The higher affinity of methanol for the formation of W-OS hydrogen bonds at the soft, hydrophobic surface presented by the bonded-phase (C18) chains reduces the OS excess and the related viscosity drop in the ditch. The lower eluting power of methanol, however, translates to increased bonded-phase contacts for analytes, which can increase their mobility gain from surface diffusion above the gain observed with acetonitrile.
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Affiliation(s)
- Andreas Steinhoff
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032Marburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032Marburg, Germany
| | - Nicole Trebel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032Marburg, Germany
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3
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Trebel N, Höltzel A, Tallarek U. Confinement Effects on Distribution and Transport of Neutral Solutes in a Small Hydrophobic Nanopore. J Phys Chem B 2022; 126:7781-7795. [PMID: 36149739 DOI: 10.1021/acs.jpcb.2c04924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Molecular dynamics simulations are used to study confinement effects in small cylindrical silica pores with extended hydrophobic surface functionalization as realized, for example, in reversed-phase liquid chromatography (RPLC) columns. In particular, we use a 6 nm cylindrical and a 10 nm slit pore bearing the same C18 stationary phase to compare the conditions inside the smaller-than-average pores within an RPLC column to column-averaged properties. Two small, neutral, apolar to moderately polar solutes are used to assess the consequences of spatial confinement for typical RPLC analytes with water (W)-acetonitrile (ACN) mobile phases at W/ACN ratios between 70/30 and 10/90 (v/v). The simulated data show that true bulk liquid behavior, as observed over an extended center region in the 10 nm slit pore, is not recovered within the 6 nm cylindrical pore. Instead, the ACN-enriched solvent layer around the C18 chain ends (the ACN ditch), a general feature of hydrophobic interfaces equilibrated with aqueous-organic liquids, extends over the entire pore lumen of the small cylindrical pore. This renders the entire pore a highly hydrophobic environment, where, contrary to column-averaged behavior, neither the local nor the pore-averaged sorption and diffusion of analytes scales directly with the W/ACN ratio of the mobile phase. Additionally, the solute polarity-related discrimination between analytes is enhanced. The consequences of local ACN ditch overlap in RPLC columns are reminiscent of ion transport in porous media with charged surfaces, where electrical double-layer overlap occurring locally in smaller pores leads to discrimination between co- and counterionic species.
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Affiliation(s)
- Nicole Trebel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
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4
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Roider T, Frommknecht N, Höltzel A, Tallarek U. Device for automated screening of irradiation wavelength and intensity – investigation of the wavelength dependence of photoreactions with an arylazo sulfone in continuous flow. REACT CHEM ENG 2022. [DOI: 10.1039/d2re00142j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A system allowing the automatic change of LED arrays (normalized to the number of emitted photons) is presented to study photochemical reactions in continuous flow for their wavelength dependence.
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Affiliation(s)
- Thomas Roider
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
| | - Norbert Frommknecht
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
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5
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Trebel N, Höltzel A, Lutz JK, Tallarek U. Consequences of Cylindrical Pore Geometry for Interfacial Phenomena in Reversed-Phase Liquid Chromatography. J Phys Chem B 2021; 125:11320-11336. [PMID: 34610741 DOI: 10.1021/acs.jpcb.1c06732] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The interfacial phenomena behind analyte separation in a reversed-phase liquid chromatography column take place nearly exclusively inside the silica mesopores. Their cylindrical geometry can be expected to shape the properties of the chromatographic interface with consequences for the analyte density distribution and diffusivity. To investigate this topic through molecular dynamics simulations, we introduce a cylindrical pore inside a slit pore configuration, where the inner curved and outer planar silica surface bear the same bonded phase. The present model replicates an average-sized (9 nm) mesopore in an endcapped C18 column equilibrated with a mobile phase of 70/30 (v/v) water/acetonitrile. Simulations performed for ethylbenzene and acetophenone show that the surface curvature shifts the bonded phase and analyte density toward the pore center, decreases the solvent density in the bonded-phase region, increases the acetonitrile excess in the interfacial region, and considerably enhances the surface diffusivity of both analytes. Overall, the cylindrical pore provides a more hydrophobic environment than the slit pore. Ethylbenzene density is decidedly increased in the cylindrical pore, whereas acetophenone density is nearly equally distributed between the cylindrical and slit pore. The cylindrical pore geometry thus sharpens the discrimination between the apolar and moderately polar analytes while enhancing the mass transport of both.
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Affiliation(s)
- Nicole Trebel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Julia K Lutz
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
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Kraus H, Rybka J, Höltzel A, Trebel N, Tallarek U, Hansen N. PoreMS: a software tool for generating silica pore models with user-defined surface functionalisation and pore dimensions. Molecular Simulation 2021. [DOI: 10.1080/08927022.2020.1871478] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Hamzeh Kraus
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Stuttgart, Germany
| | - Julia Rybka
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Nicole Trebel
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | - Niels Hansen
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Stuttgart, Germany
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7
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Trebel N, Höltzel A, Steinhoff A, Tallarek U. Insights from molecular simulations about dead time markers in reversed-phase liquid chromatography. J Chromatogr A 2021; 1640:461958. [PMID: 33582514 DOI: 10.1016/j.chroma.2021.461958] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 01/28/2021] [Accepted: 01/29/2021] [Indexed: 11/16/2022]
Abstract
Among the most popular compounds to estimate the hold-up time in reversed-phase liquid chromatography (RPLC) are acetone and uracil, which are considered as too small and too polar, respectively, for retention by the hydrophobic stationary phase, although their observed elution behavior does not fully support this assumption. We investigate how acetone and uracil as solutes interact with the chromatographic interface through molecular dynamics simulations in an RPLC mesopore model of a silica-supported, endcapped, C18 phase equilibrated with a water (W)‒acetonitrile (ACN) mobile phase. The simulation results provide a molecular-level explanation for the observed elution behavior of acetone and uracil, but also question whether true dead time markers for RPLC exist. Both solutes have a density maximum in the interfacial region in addition to a low presence in the bonded-phase region, but these density peaks clearly differ from the adsorption and partitioning peaks of true analytes. Acetone partially behaves like a co-solvent of ACN and partially like the analyte acetophenone. Like ACN, acetone can be found in the first and second layer of solvent molecules at the silica surface; like acetophenone, acetone adsorbs to the bonded-phase chains by orienting its polar group to the bulk region to sustain hydrogen bonds with W molecules. Uracil behavior is governed by a need for extensive hydrogen-bond coordination by W molecules. Uracil adsorbs to the very edge of the bonded-phase chains, on the bulk-region side of the ACN density maximum in the interfacial region. Further penetration into the chains is prevented by the absence of W molecules, which are not found deeper in the bonded phase, except at the silica surface. Contrary to true analytes, accumulation of uracil and acetone in the interfacial region ceases at an equimolar presence of W and ACN in the mobile phase (at 70‒80% ACN volume fraction). Uracil achieves a closer approximation of the stationary-phase limit than acetone, but carries the risk of HILIC retention at high ACN fraction in the mobile phase.
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Affiliation(s)
- Nicole Trebel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Andreas Steinhoff
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany.
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8
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Hochstrasser J, Svidrytski A, Höltzel A, Priamushko T, Kleitz F, Wang W, Kübel C, Tallarek U. Morphology-transport relationships for SBA-15 and KIT-6 ordered mesoporous silicas. Phys Chem Chem Phys 2020; 22:11314-11326. [PMID: 32406894 DOI: 10.1039/d0cp01861a] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Quantitative morphology-transport relationships are derived for ordered mesoporous silicas through direct numerical simulation of hindered diffusion in realistic geometrical models of the pore space obtained from physical reconstruction by electron tomography. We monitor accessible porosity and effective diffusion coefficients resulting from steric and hydrodynamic interactions between passive tracers and the pore space confinement as a function of λ = dtracer/dmeso (ratio of tracer diameter to mean mesopore diameter) in SBA-15 (dmeso = 9.1 nm) and KIT-6 (dmeso = 10.5 nm) silica samples. For λ = 0, the pointlike tracers reproduce the true diffusive tortuosities. For 0 ≤λ < 0.5, the derived hindrance factor quantifies the extent to which diffusion of finite-size tracers through the materials is hindered compared with free diffusion in the bulk liquid. The hindrance factor connects the transport properties of the ordered silicas to their mesopore space morphologies and enables quantitative comparison with random mesoporous silicas. Key feature of the ordered silicas is a narrow, symmetric mesopore size distribution (∼10% relative standard deviation), which engenders a sharper decline of the accessible-porosity window with increasing λ than observed for random silicas with their wide, asymmetric mesopore size distributions. As support structures, ordered mesoporous silicas should offer benefits for applications where spatial confinement effects and molecular size-selectivity are of prime importance. On the other hand, random mesoporous silicas enable higher diffusivities for λ > 0.3, because the larger pores carry most of the diffusive flux and keep pathways open when smaller pores have closed off.
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Affiliation(s)
- Janika Hochstrasser
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany.
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9
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Reich SJ, Svidrytski A, Hlushkou D, Stoeckel D, Kübel C, Höltzel A, Tallarek U. Hindrance Factor Expression for Diffusion in Random Mesoporous Adsorbents Obtained from Pore-Scale Simulations in Physical Reconstructions. Ind Eng Chem Res 2018. [DOI: 10.1021/acs.iecr.7b04840] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Stefan-Johannes Reich
- Department
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Artur Svidrytski
- Department
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Dzmitry Hlushkou
- Department
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Daniela Stoeckel
- Department
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
- Institute of Physical Chemistry, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 58, 35392 Gießen, Germany
| | - Christian Kübel
- Institute
of Nanotechnology and Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Alexandra Höltzel
- Department
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Ulrich Tallarek
- Department
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
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Kohns R, Haas CP, Höltzel A, Splith C, Enke D, Tallarek U. Hierarchical silica monoliths with submicron macropores as continuous-flow microreactors for reaction kinetic and mechanistic studies in heterogeneous catalysis. REACT CHEM ENG 2018. [DOI: 10.1039/c8re00037a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The proposed scheme enables academic laboratories to prepare hierarchical silica monoliths as continuous-flow microreactors for kinetic studies in heterogeneous catalysis.
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Affiliation(s)
- Richard Kohns
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
- Institute of Chemical Technology
| | - Christian P. Haas
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
| | - Alexandra Höltzel
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
| | - Christian Splith
- Institute of Chemical Technology
- Universität Leipzig
- 04103 Leipzig
- Germany
| | - Dirk Enke
- Institute of Chemical Technology
- Universität Leipzig
- 04103 Leipzig
- Germany
| | - Ulrich Tallarek
- Department of Chemistry
- Philipps-Universität Marburg
- 35032 Marburg
- Germany
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11
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Müllner T, Zankel A, Höltzel A, Svec F, Tallarek U. Morphological Properties of Methacrylate-Based Polymer Monoliths: From Gel Porosity to Macroscopic Inhomogeneities. Langmuir 2017; 33:2205-2214. [PMID: 28186759 DOI: 10.1021/acs.langmuir.7b00337] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Shaping chemical interfaces of hard and soft matter materials into physical morphologies that guarantee excellent transport properties is of central importance for technologies relying on adsorption, separation, and reaction at the interface. Polymer monoliths with a hierarchically structured pore space, for example, are widely used in flow-driven processes, whose efficiency depends on the morphology of the support material over several length scales. Compared with alternative support structures, particularly silica monoliths, polymer monoliths yield lower efficiency, which suggests a suboptimal morphology. Based on physical reconstruction by serial block-face scanning electron microscopy we evaluate the structural features of a methacrylate-based polymer monolith from the pore scale to the column scale. The morphological data reveal a homogeneous polymer skeleton with a solute-impenetrable core-porous shell architecture and a heterogeneous macropore space that suffers from inhomogeneities at the short-range and the transcolumn scale. Although the morphology of the polymer phase is favorable to efficient mass transport, the performance of the polymer monolith is limited by severe transcolumn gradients in macroporosity and macropore size. We propose to overcome these morphological limitations by pursuing a preparation strategy that involves active rather than passive shaping of the macropore space, for example, by using silica monoliths as templating structures for polymer monolith preparation.
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Affiliation(s)
- Tibor Müllner
- Department of Chemistry, Philipps-Universität Marburg , Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Armin Zankel
- Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology, and Graz Centre for Electron Microscopy, Steyrergasse 17, 8010 Graz, Austria
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg , Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
| | - Frantisek Svec
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology , 100029 Beijing, China
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg , Hans-Meerwein-Strasse 4, 35032 Marburg, Germany
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12
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Hormann K, Baranau V, Hlushkou D, Höltzel A, Tallarek U. Topological analysis of non-granular, disordered porous media: determination of pore connectivity, pore coordination, and geometric tortuosity in physically reconstructed silica monoliths. NEW J CHEM 2016. [DOI: 10.1039/c5nj02814k] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Different approaches are applied and compared, which are universally applicable to quantify pore coordination, pore and pore-throat connectivity, and geometric tortuosity.
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Affiliation(s)
- Kristof Hormann
- Department of Chemistry
- Philipps-Universität Marburg
- D-35032 Marburg
- Germany
| | - Vasili Baranau
- Department of Chemistry
- Philipps-Universität Marburg
- D-35032 Marburg
- Germany
| | - Dzmitry Hlushkou
- Department of Chemistry
- Philipps-Universität Marburg
- D-35032 Marburg
- Germany
| | - Alexandra Höltzel
- Department of Chemistry
- Philipps-Universität Marburg
- D-35032 Marburg
- Germany
| | - Ulrich Tallarek
- Department of Chemistry
- Philipps-Universität Marburg
- D-35032 Marburg
- Germany
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Müllner T, Zankel A, Lv Y, Svec F, Höltzel A, Tallarek U. Assessing structural correlations and heterogeneity length scales in functional porous polymers from physical reconstructions. Adv Mater 2015; 27:6009-6013. [PMID: 26314251 DOI: 10.1002/adma.201502332] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 07/16/2015] [Indexed: 06/04/2023]
Abstract
A general, model-free, quantitative approach to the key morphological properties of a porous polymer monolith is presented. After 3D reconstruction, image-based analysis delivers detailed spatial and spatially correlated information on the structural heterogeneities in the void space and the polymer skeleton. Identified heterogeneities, which limit the monolith's performance in targeted applications, are traced back to the preparation process.
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Affiliation(s)
- Tibor Müllner
- Philipps-Universität Marburg, Department of Chemistry, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany
| | - Armin Zankel
- Graz University of Technology, NAWI Graz, Institute for Electron Microscopy and Nanoanalysis and Center for Electron Microscopy, Steyrergasse 17, 8010, Graz, Austria
| | - Yongqin Lv
- International Research Center for Soft Matter, Beijing University of Chemical Technology, 100029, Beijing, China
| | - Frantisek Svec
- International Research Center for Soft Matter, Beijing University of Chemical Technology, 100029, Beijing, China
| | - Alexandra Höltzel
- Philipps-Universität Marburg, Department of Chemistry, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany
| | - Ulrich Tallarek
- Philipps-Universität Marburg, Department of Chemistry, Hans-Meerwein-Strasse 4, 35032, Marburg, Germany
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Hlushkou D, Hormann K, Höltzel A, Tallarek U, Seidel-Morgenstern A. From Physical Reconstruction to Pore-Scale Transport Simulations: Comparison of First- and Second-Generation Analytical Silica Monoliths. CHEM-ING-TECH 2014. [DOI: 10.1002/cite.201450544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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15
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Hormann K, Stoeckel D, Kübel C, Höltzel A, Smarsly B, Tallarek U. From Macropores to Mesopores: 3D Morphology of Hierarchical Porous Solids. CHEM-ING-TECH 2014. [DOI: 10.1002/cite.201450624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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16
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Tallarek U, Rybka J, Melnikov S, Höltzel A, Seidel-Morgenstern A. Einfluss der Oberflächenpolarität auf Struktur und Mobilität binärer Lösungsmittelgemische mittels molekulardynamischer Simulationen. CHEM-ING-TECH 2014. [DOI: 10.1002/cite.201450577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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17
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Stoeckel D, Kübel C, Hormann K, Höltzel A, Smarsly BM, Tallarek U. Morphological analysis of disordered macroporous-mesoporous solids based on physical reconstruction by nanoscale tomography. Langmuir 2014; 30:9022-9027. [PMID: 25036976 DOI: 10.1021/la502381m] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Solids with a hierarchically structured, disordered pore space, such as macroporous-mesoporous silica monoliths, are used as fixed beds in separation and catalysis. Targeted optimization of their functional properties requires a knowledge of the relation among their synthesis, morphology, and mass transport properties. However, an accurate and comprehensive morphological description has not been available for macroporous-mesoporous silica monoliths. Here we offer a solution to this problem based on the physical reconstruction of the hierarchically structured pore space by nanoscale tomography. Relying exclusively on image analysis, we deliver a concise, accurate, and model-free description of the void volume distribution and pore coordination inside the silica monolith. Structural features are connected to key transport properties (effective diffusion, hydrodynamic dispersion) of macropore and mesopore space. The presented approach is applicable to other fixed-bed formats of disordered macroporous-mesoporous solids, such as packings of mesoporous particles and organic-polymer monoliths.
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Affiliation(s)
- Daniela Stoeckel
- Department of Chemistry, Philipps-Universität Marburg , Hans-Meerwein-Strasse, 35032 Marburg, Germany
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Melnikov SM, Höltzel A, Seidel-Morgenstern A, Tallarek U. How Ternary Mobile Phases Allow Tuning of Analyte Retention in Hydrophilic Interaction Liquid Chromatography. Anal Chem 2013; 85:8850-6. [DOI: 10.1021/ac402123a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Sergey M. Melnikov
- Department
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
- Max-Planck-Institut für Dynamik komplexer technischer Systeme, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Alexandra Höltzel
- Department
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Andreas Seidel-Morgenstern
- Max-Planck-Institut für Dynamik komplexer technischer Systeme, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Ulrich Tallarek
- Department
of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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Melnikov S, Höltzel A, Seidel-Morgenstern A, Tallarek U. Adsorption von Wasser/Acetonitril-Gemischen an Kieselgel-Modelloberflächen. CHEM-ING-TECH 2013. [DOI: 10.1002/cite.201250699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Khirevich S, Höltzel A, Seidel-Morgenstern A, Tallarek U. Geometrical and topological measures for hydrodynamic dispersion in confined sphere packings at low column-to-particle diameter ratios. J Chromatogr A 2012; 1262:77-91. [PMID: 23000179 DOI: 10.1016/j.chroma.2012.08.086] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 08/28/2012] [Accepted: 08/29/2012] [Indexed: 10/27/2022]
Abstract
At low column-to-particle diameter (or aspect) ratio (d(c)/d(p)) the kinetic column performance is dominated by the transcolumn disorder that arises from the morphological gradient between the more homogeneous, looser packed wall region and the random, dense core. For a systematic analysis of this morphology-dispersion relation we computer-generated a set of confined sphere packings varying three parameters: aspect ratio (d(c)/d(p)=10-30), bed porosity (ɛ=0.40-0.46), and packing homogeneity. Plate height curves were received from simulation of hydrodynamic dispersion in the packings over a wide range of reduced velocities (v=0.5-500). Geometrical measures derived from radial porosity and velocity profiles were insufficient as morphological descriptors of the plate height data. After Voronoi tessellation of the packings, topological information was obtained from the statistical moments of the free Voronoi volume (V(free)) distributions. The radial profile of the standard deviation of the V(free) distributions in the form of an integral measure was identified as a quantitative scalar measure for the transcolumn disorder. The first morphology-dispersion correlation for confined sphere packings deepens our understanding of how the packing microstructure determines the kinetic column performance.
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Affiliation(s)
- Siarhei Khirevich
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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21
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Melnikov SM, Höltzel A, Seidel-Morgenstern A, Tallarek U. Eine Moleküldynamikstudie zum Verteilungsmechanismus in der Hydrophilen Interaktionschromatographie. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201201096] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Melnikov SM, Höltzel A, Seidel-Morgenstern A, Tallarek U. A Molecular Dynamics Study on the Partitioning Mechanism in Hydrophilic Interaction Chromatography. Angew Chem Int Ed Engl 2012; 51:6251-4. [DOI: 10.1002/anie.201201096] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Revised: 03/09/2012] [Indexed: 11/10/2022]
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Daneyko A, Khirevich S, Höltzel A, Seidel-Morgenstern A, Tallarek U. From random sphere packings to regular pillar arrays: Effect of the macroscopic confinement on hydrodynamic dispersion. J Chromatogr A 2011; 1218:8231-48. [DOI: 10.1016/j.chroma.2011.09.039] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 09/06/2011] [Accepted: 09/13/2011] [Indexed: 11/16/2022]
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Khirevich S, Höltzel A, Tallarek U. Transient and asymptotic dispersion in confined sphere packings with cylindrical and non-cylindrical conduit geometries. Philos Trans A Math Phys Eng Sci 2011; 369:2485-2493. [PMID: 21576163 DOI: 10.1098/rsta.2011.0027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We study the time and length scales of hydrodynamic dispersion in confined monodisperse sphere packings as a function of the conduit geometry. By a modified Jodrey-Tory algorithm, we generated packings at a bed porosity (interstitial void fraction) of ε=0.40 in conduits with circular, rectangular, or semicircular cross section of area 100πd(p)(2) (where d(p) is the sphere diameter) and dimensions of about 20d(p) (cylinder diameter) by 6553.6d(p) (length), 25d(p) by 12.5d(p) (rectangle sides) by 8192d(p) or 14.1d(p) (radius of semicircle) by 8192d(p), respectively. The fluid-flow velocity field in the generated packings was calculated by the lattice Boltzmann method for Péclet numbers of up to 500, and convective-diffusive mass transport of 4×10(6) inert tracers was modelled with a random-walk particle-tracking technique. We present lateral porosity and velocity distributions for all packings and monitor the time evolution of longitudinal dispersion up to the asymptotic (long-time) limit. The characteristic length scales for asymptotic behaviour are explained from the symmetry of each conduit's velocity field. Finally, we quantify the influence of the confinement and of a specific conduit geometry on the velocity dependence of the asymptotic dispersion coefficients.
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Affiliation(s)
- Siarhei Khirevich
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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Daneyko A, Höltzel A, Khirevich S, Tallarek U. Influence of the Particle Size Distribution on Hydraulic Permeability and Eddy Dispersion in Bulk Packings. Anal Chem 2011; 83:3903-10. [DOI: 10.1021/ac200424p] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anton Daneyko
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Siarhei Khirevich
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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Affiliation(s)
- Dzmitry Hlushkou
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Stefan Bruns
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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Bruns S, Müllner T, Kollmann M, Schachtner J, Höltzel A, Tallarek U. Confocal Laser Scanning Microscopy Method for Quantitative Characterization of Silica Monolith Morphology. Anal Chem 2010; 82:6569-75. [DOI: 10.1021/ac100909t] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Stefan Bruns
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Department of Biology, Philipps-Universität Marburg, Karl-von-Frisch-Strasse 8, 35032 Marburg, Germany
| | - Tibor Müllner
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Department of Biology, Philipps-Universität Marburg, Karl-von-Frisch-Strasse 8, 35032 Marburg, Germany
| | - Martin Kollmann
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Department of Biology, Philipps-Universität Marburg, Karl-von-Frisch-Strasse 8, 35032 Marburg, Germany
| | - Joachim Schachtner
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Department of Biology, Philipps-Universität Marburg, Karl-von-Frisch-Strasse 8, 35032 Marburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Department of Biology, Philipps-Universität Marburg, Karl-von-Frisch-Strasse 8, 35032 Marburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Department of Biology, Philipps-Universität Marburg, Karl-von-Frisch-Strasse 8, 35032 Marburg, Germany
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Khirevich S, Daneyko A, Höltzel A, Seidel-Morgenstern A, Tallarek U. Statistical analysis of packed beds, the origin of short-range disorder, and its impact on eddy dispersion. J Chromatogr A 2010; 1217:4713-22. [DOI: 10.1016/j.chroma.2010.05.019] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Revised: 05/03/2010] [Accepted: 05/07/2010] [Indexed: 10/19/2022]
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Abstract
Time and length scales as well as the magnitude of individual contributions to eddy dispersion in chromatographic beds are resolved. We address this issue by a high-resolution numerical analysis of flow and mass transport in computer-generated bulk (unconfined) packings of monosized, nonporous, incompressible, spherical particles and complementary confined cylindrical packings with a cylinder-to-particle diameter ratio of d(c)/d(p) = 20. The transient behavior of longitudinal and transverse dispersion is analyzed and correlated with the spatial scales of heterogeneity in the bulk and confined packings. Simulations were carried out until complete transcolumn equilibration in the confined packings was achieved to facilitate a quantitative study of the geometrical wall effect. Longitudinal plate height data calculated over a wide range of reduced velocities (0.1 < or = nu < or = 500) were fitted to the comprehensive Giddings equation. The determined transition velocities for individual contributions to eddy dispersion were found to be widely disparate. As a consequence, the total effect of eddy dispersion on the plate height curves can be approximated in the practical range of chromatographic operational velocities (5 < or = nu < or = 20) by a composite expression in which only the short-range interchannel contribution retains its coupling characteristics, while transchannel and transcolumn contributions appear as simple mass transfer velocity-proportional terms.
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Affiliation(s)
- Siarhei Khirevich
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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Nischang I, Höltzel A, Tallarek U. Electrochromatographic retention of peptides on strong cation-exchange stationary phases. Electrophoresis 2010; 31:933-43. [DOI: 10.1002/elps.200900549] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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31
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Jung S, Höltzel A, Ehlert S, Mora JA, Kraiczek K, Dittmann M, Rozing GP, Tallarek U. Impact of Conduit Geometry on the Performance of Typical Particulate Microchip Packings. Anal Chem 2009; 81:10193-200. [DOI: 10.1021/ac902069x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stephanie Jung
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Agilent Technologies, Hewlett-Packard-Strasse 8, 76337 Waldbronn, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Agilent Technologies, Hewlett-Packard-Strasse 8, 76337 Waldbronn, Germany
| | - Steffen Ehlert
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Agilent Technologies, Hewlett-Packard-Strasse 8, 76337 Waldbronn, Germany
| | - Jose-Angel Mora
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Agilent Technologies, Hewlett-Packard-Strasse 8, 76337 Waldbronn, Germany
| | - Karsten Kraiczek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Agilent Technologies, Hewlett-Packard-Strasse 8, 76337 Waldbronn, Germany
| | - Monika Dittmann
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Agilent Technologies, Hewlett-Packard-Strasse 8, 76337 Waldbronn, Germany
| | - Gerard P. Rozing
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Agilent Technologies, Hewlett-Packard-Strasse 8, 76337 Waldbronn, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Agilent Technologies, Hewlett-Packard-Strasse 8, 76337 Waldbronn, Germany
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Khirevich S, Höltzel A, Seidel-Morgenstern A, Tallarek U. Struktur-Transport-Analyse in Festbetten verschiedener Querschnittsgeometrien. CHEM-ING-TECH 2009. [DOI: 10.1002/cite.200950056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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33
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Khirevich S, Höltzel A, Ehlert S, Seidel-Morgenstern A, Tallarek U. Large-Scale Simulation von Fluss und Transport in rekonstruierten Festbetten. CHEM-ING-TECH 2009. [DOI: 10.1002/cite.200950055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Khirevich S, Höltzel A, Ehlert S, Seidel-Morgenstern A, Tallarek U. Large-Scale Simulation of Flow and Transport in Reconstructed HPLC-Microchip Packings. Anal Chem 2009; 81:4937-45. [DOI: 10.1021/ac900631d] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Siarhei Khirevich
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Max-Planck-Institut für Dynamik komplexer technischer Systeme, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Alexandra Höltzel
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Max-Planck-Institut für Dynamik komplexer technischer Systeme, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Steffen Ehlert
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Max-Planck-Institut für Dynamik komplexer technischer Systeme, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Andreas Seidel-Morgenstern
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Max-Planck-Institut für Dynamik komplexer technischer Systeme, Sandtorstrasse 1, 39106 Magdeburg, Germany
| | - Ulrich Tallarek
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany, and Max-Planck-Institut für Dynamik komplexer technischer Systeme, Sandtorstrasse 1, 39106 Magdeburg, Germany
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Khirevich S, Höltzel A, Hlushkou D, Seidel-Morgenstern A, Tallarek U. Structure-transport analysis for particulate packings in trapezoidal microchip separation channels. Lab Chip 2008; 8:1801-1808. [PMID: 18941678 DOI: 10.1039/b810688f] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This article investigates the efficiency of particulate beds confined in quadrilateral microchannels by analyzing the three-dimensional fluid flow velocity field and accompanying hydrodynamic dispersion with quantitative numerical simulation methods. Random-close packings of uniform, solid (impermeable), spherical particles of diameter d(p) were generated by a modified Jodrey-Tory algorithm in eighteen different conduits with quadratic, rectangular, or trapezoidal cross-section at an average bed porosity (interparticle void fraction) of epsilon = 0.48. Velocity fields were calculated by the lattice Boltzmann method, and axial hydrodynamic dispersion of an inert tracer was simulated at Péclet numbers Pe = u(av)d(p)/D(m) (where u(av) is the average fluid flow velocity through a packing and D(m) the bulk molecular diffusion coefficient) from Pe = 5 to Pe = 30 by a Lagrangian particle-tracking method. All conduits had a cross-sectional area of 100d(p)(2) and a length of 1200d(p), translating to around 10(5) particles per packing. We present lateral porosity distribution functions and analyze fluid flow profiles and velocity distribution functions with respect to the base angle and the aspect ratio of the lateral dimensions of the different conduits. We demonstrate significant differences between the top and bottom parts of trapezoidal packings in their lateral porosity and velocity distribution functions, and show that these differences increase with decreasing base angle and increasing base-aspect ratio of a trapezoidal conduit, i.e., with increasing deviation from regular rectangular geometry. Efficiencies are investigated in terms of the axial hydrodynamic dispersion coefficients as a function of the base angle and base-aspect ratio of the conduits. The presented data support the conclusion that the efficiency of particulate beds in trapezoidal microchannels strongly depends on the lateral dimensions of the conduit and that cross-sectional designs based on large side-aspect-ratio rectangles with limited deviations from orthogonality are favorable.
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Affiliation(s)
- Siarhei Khirevich
- Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032, Marburg, Germany
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Nischang I, Höltzel A, Seidel-Morgenstern A, Tallarek U. Concentration polarization and nonequilibrium electroosmotic slip in hierarchical monolithic structures. Electrophoresis 2008; 29:1140-51. [DOI: 10.1002/elps.200700727] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Khirevich S, Höltzel A, Hlushkou D, Tallarek U. Impact of Conduit Geometry and Bed Porosity on Flow and Dispersion in Noncylindrical Sphere Packings. Anal Chem 2007; 79:9340-9. [DOI: 10.1021/ac071428k] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Siarhei Khirevich
- Institut für Verfahrenstechnik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, and Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Alexandra Höltzel
- Institut für Verfahrenstechnik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, and Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Dzmitry Hlushkou
- Institut für Verfahrenstechnik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, and Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
| | - Ulrich Tallarek
- Institut für Verfahrenstechnik, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany, and Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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Abstract
In this tutorial review we illustrate the origin and dependence on various system parameters of the ionic conductance that exists in discrete nanochannels as well as in nanoporous separation and preconcentration units contained as hybrid configurations, membranes, packed beds, or monoliths in microscale liquid phase analysis systems. A particular complexity arises as external electrical fields are superimposed on internal chemical and electrical potential gradients for tailoring molecular transport. It is demonstrated that the variety of geometries in which the microfluidic/nanofluidic interfaces are realized share common, fundamental features of coupled mass and charge transport, but that phenomena behind the key steps in a particular application can be significantly tuned, depending on the morphology of a material. Thus, the understanding of morphology-related transport in internal and external electrical potential gradients is critical to the performance of a device. This addresses a variety of geometries (slits, channels, filters, membranes, random or regular networks of pores, etc.) and applications, e. g., the gating, sensing, preconcentration, and separation in multifunctional miniaturized devices. Inherently coupled mass and charge transport through ion-permselective (charge-selective) microfluidic/nanofluidic interfaces is analyzed with a stepwise-added complexity and discussed with respect to the morphology of the charge-selective spatial domains. Within this scenario, the electrostatics and electrokinetics in microfluidic and nanofluidic channels, as well as the electrohydrodynamics evolving at microfluidic/nanofluidic interfaces, where microfluidics meets nanofluidics, define the platform of central phenomena.
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Affiliation(s)
- Alexandra Höltzel
- Institut für Verfahrenstechnik, Otto-von-Guericke-Universität, Magdeburg, Germany
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Gebhardt K, Schimana J, Höltzel A, Dettner K, Draeger S, Beil W, Rheinheimer J, Fiedler HP. Aspochalamins A-D and aspochalasin Z produced by the endosymbiotic Fungus aspergillus niveus LU 9575. I. Taxonomy, fermentation, isolation and biological activities. J Antibiot (Tokyo) 2005; 57:707-14. [PMID: 15712664 DOI: 10.7164/antibiotics.57.707] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aspochalamins A-D, a family of new cytochalasan antibiotics have been isolated from Aspergillus niveus, an endosymbiotic fungus isolated from the gut of a woodlouse belonging to the family Trichoniscidae. Besides aspochalamins, aspochalasin Z, a new member of the aspochalasin family, as well as the known mycotoxins aspochalasin D and citreoviridins A/C and B were isolated from the mycelium. Aspochalamins showed cytostatic effects towards various tumor cell lines and a weak antibacterial activity against Gram-positive bacteria.
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Affiliation(s)
- Klaus Gebhardt
- Mikrobiologisches Institut, Universität Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany
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Potterat O, Hostettmann K, Höltzel A, Jung G, Diehl PA, Petrini O. Boophiline, an antimicrobial sterol amide from the cattle tickboophilus microplus. Helv Chim Acta 2004. [DOI: 10.1002/hlca.19970800707] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Höltzel A, Dieter A, Schmid DG, Brown R, Goodfellow M, Beil W, Jung G, Fiedler HP. Lactonamycin Z, an Antibiotic and Antitumor Compound Produced by Streptomyces sanglieri Strain AK 623. J Antibiot (Tokyo) 2003; 56:1058-61. [PMID: 15015734 DOI: 10.7164/antibiotics.56.1058] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Alexandra Höltzel
- Institut für Organische Chemie, Universität Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany
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Gebhardt K, Schimana J, Müller J, Fiedler HP, Kallenborn HG, Holzenkämpfer M, Krastel P, Zeeck A, Vater J, Höltzel A, Schmid DG, Rheinheimer J, Dettner K. Screening for biologically active metabolites with endosymbiotic bacilli isolated from arthropods. FEMS Microbiol Lett 2002; 217:199-205. [PMID: 12480104 DOI: 10.1111/j.1574-6968.2002.tb11475.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Endosymbiotic bacteria from the genus Bacillus were isolated from different compartments of the gut of various members of insects (Hexapoda) and millipedes (Diplopoda). They were grown in submerged culture and investigated by biological assays and HPLC-diode array analysis regarding their production of bioactive metabolites, which were isolated and determined in structure. Known compounds and yet unknown derivatives from the primary metabolism were detected, as well as antibacterially and antifungally acting peptide antibiotics.
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Affiliation(s)
- Klaus Gebhardt
- Mikrobiologisches Institut, Universität Tübingen, D-72076 Tübingen, Germany
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Schimana J, Gebhardt K, Höltzel A, Schmid DG, Süssmuth R, Müller J, Pukall R, Fiedler HP. Arylomycins A and B, new biaryl-bridged lipopeptide antibiotics produced by Streptomyces sp. Tü 6075. I. Taxonomy, fermentation, isolation and biological activities. J Antibiot (Tokyo) 2002; 55:565-70. [PMID: 12195962 DOI: 10.7164/antibiotics.55.565] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
New lipopeptide antibiotics, colourless arylomycins A series and yellow arylomycins B series were detected in the culture filtrate and mycelium extracts of Streptomyces sp. Tü 6075 by HPLC-diode-array and HPLC-electrospray-mass-spectrometry screening. Arylomycins are a family of lipohexapeptide antibiotics, which represent the first examples of biaryl-bridged lipopeptides. They show antibiotic activities against Gram-positive bacteria.
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MESH Headings
- Anti-Bacterial Agents/biosynthesis
- Anti-Bacterial Agents/isolation & purification
- Anti-Bacterial Agents/pharmacology
- Chromatography, High Pressure Liquid
- DNA, Bacterial/chemistry
- DNA, Bacterial/genetics
- Microbial Sensitivity Tests
- Peptides, Cyclic/biosynthesis
- Peptides, Cyclic/isolation & purification
- Peptides, Cyclic/pharmacology
- Polymerase Chain Reaction
- RNA, Ribosomal, 16S/chemistry
- RNA, Ribosomal, 16S/genetics
- Sequence Analysis, DNA
- Soil Microbiology
- Streptomyces/chemistry
- Streptomyces/classification
- Streptomyces/genetics
- Streptomyces/metabolism
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Affiliation(s)
- Judith Schimana
- Mikrobiologisches Institut, Universität Tübingen, Auf der Morgenstelle 28, D-72076 Tübingen, Germany
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Höltzel A, Schmid DG, Nicholson GJ, Stevanovic S, Schimana J, Gebhardt K, Fiedler HP, Jung G. Arylomycins A and B, new biaryl-bridged lipopeptide antibiotics produced by Streptomyces sp. Tü 6075. II. Structure elucidation. J Antibiot (Tokyo) 2002; 55:571-7. [PMID: 12195963 DOI: 10.7164/antibiotics.55.571] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structures of new lipopeptide antibiotics, arylomycins A and B, were elucidated by a combination of ESI-FTICR-mass spectrometry, NMR spectroscopy, Edman sequencing, and fatty acid and chiral amino acid analyses. The colourless arylomycins A share the peptide sequence of D-N-methylseryl2(D-MeSer2)-D-alanyl3-glycyl4-N-methyl- 4-hydroxyphenylglycyl5(MeHpg5)-L-alanyl6-tyrosine7 cyclised by a [3,3]biaryl bond between MeHpg5 and Tyr7. The yellow arylomycins B differ from arylomycins A by nitro substitution of Tyr7. The N-termini of arylomycins A and B are acylated with saturated C11-C15 fatty acids (fa1) comprising n, iso, and anteiso isomers. Arylomycins A and B represent the first examples of biaryl-bridged lipopeptides.
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Affiliation(s)
- Alexandra Höltzel
- Institut fur Organische Chemie, Universität Tübingen, Auf der Morgenstelle 18, D-72076 Tübingen, Germany
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Bischoff D, Pelzer S, Höltzel A, Nicholson GJ, Stockert S, Wohlleben W, Jung G, Süssmuth RD. Die Biosynthese von Glycopeptid-Antibiotika des Vancomycin-Typs - neue Einblicke in die Abfolge der Ringschlüsse. Angew Chem Int Ed Engl 2001. [DOI: 10.1002/1521-3757(20010504)113:9<1736::aid-ange17360>3.0.co;2-b] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Bischoff D, Pelzer S, Höltzel A, Nicholson GJ, Stockert S, Wohlleben W, Jung G, Süssmuth RD. The Biosynthesis of Vancomycin-Type Glycopeptide Antibiotics—New Insights into the Cyclization Steps. Angew Chem Int Ed Engl 2001; 40:1693-1696. [PMID: 11353482 DOI: 10.1002/1521-3773(20010504)40:9<1693::aid-anie16930>3.0.co;2-8] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Daniel Bischoff
- Institut für Organische Chemie der Universität Tübingen Auf der Morgenstelle 18, 72076 Tübingen (Germany)
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Höltzel A, Jack RW, Nicholson GJ, Jung G, Gebhardt K, Fiedler HP, Süssmuth RD. Streptocidins A-D, novel cyclic decapeptide antibiotics produced by Streptomyces sp. Tü 6071. II. Structure elucidation. J Antibiot (Tokyo) 2001; 54:434-40. [PMID: 11480887 DOI: 10.7164/antibiotics.54.434] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structures of the new antibiotics streptocidins A approximately D were elucidated as cyclic decapeptides cyclo[L-Val1-L-Orn2-L-Leu3-D-Phe4-L-Pro5-L-Leu6-X7-L-Asn8-L-Gln9-X10] with X7=D-Trp (A, B, C) or D-Phe (D) and X10=L-Tyr (A), L-Trp (B, D), or D-Trp (C). The amino acid composition (including the configuration) of the substances was determined by chiral-phase GC-MS of the hydrolysates. The sequences were established by EDMAN degradation following linearisation of the cyclic peptides upon treatment with LiAlH4. NMR spectroscopic studies of streptocidins C and D confirmed the proposed sequences and provided conformational data which indicate a molecular topology of streptocidins C and D similar to those of tyrocidine A and gramicidin S.
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Affiliation(s)
- A Höltzel
- Institut für Organische Chemie, Universität Tübingen, Germany
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Gänzle MG, Höltzel A, Walter J, Jung G, Hammes WP. Characterization of reutericyclin produced by Lactobacillus reuteri LTH2584. Appl Environ Microbiol 2000; 66:4325-33. [PMID: 11010877 PMCID: PMC92303 DOI: 10.1128/aem.66.10.4325-4333.2000] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2000] [Accepted: 07/06/2000] [Indexed: 11/20/2022] Open
Abstract
Lactobacillus reuteri LTH2584 exhibits antimicrobial activity that can be attributed neither to bacteriocins nor to the production of reuterin or organic acids. We have purified the active compound, named reutericyclin, to homogeneity and characterized its antimicrobial activity. Reutericyclin exhibited a broad inhibitory spectrum including Lactobacillus spp., Bacillus subtilis, B. cereus, Enterococcus faecalis, Staphylococcus aureus, and Listeria innocua. It did not affect the growth of gram-negative bacteria; however, the growth of lipopolysaccharide mutant strains of Escherichia coli was inhibited. Reutericyclin exhibited a bactericidal mode of action against Lactobacillus sanfranciscensis, Staphylococcus aureus, and B. subtilis and triggered the lysis of cells of L. sanfranciscensis in a dose-dependent manner. Germination of spores of B. subtilis was inhibited, but the spores remained unaffected under conditions that do not permit germination. The fatty acid supply of the growth media had a strong effect on reutericyclin production and its distribution between producer cells and the culture supernatant. Reutericyclin was purified from cell extracts and culture supernatant of L. reuteri LTH2584 cultures grown in mMRS by solvent extraction, gel filtration, RP-C(8) chromatography, and anion-exchange chromatography, followed by rechromatography by reversed-phase high-pressure liquid chromatography. Reutericyclin was characterized as a negatively charged, highly hydrophobic molecule with a molecular mass of 349 Da. Structural characterization (A. Höltzel, M. G. Gänzle, G. J. Nicholson, W. P. Hammes, and G. Jung, Angew. Chem. Int. Ed. 39:2766-2768, 2000) revealed that reutericyclin is a novel tetramic acid derivative. The inhibitory activity of culture supernatant of L. reuteri LTH2584 corresponded to that of purified as well as synthetic reutericyclin.
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Affiliation(s)
- M G Gänzle
- Institut für Lebensmitteltechnologie, Universität Hohenheim, D-70599 Stuttgart, Germany.
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Höltzel A, Gänzle M, Nicholson G, Hammes W, Jung G. Das erste niedermolekulare Antibiotikum aus lebensmitteltechnologisch eingesetzten Milchsäurebakterien: Reutericyclin, eine neue Tetramsäure. Angew Chem Int Ed Engl 2000. [DOI: 10.1002/1521-3757(20000804)112:15<2886::aid-ange2886>3.0.co;2-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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