Gerald Brenner-Weiss

Karlsruhe Institute of Technology, Carlsruhe, Baden-Württemberg, Germany

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Publications (50)129.67 Total impact

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    Full-text · Dataset · Jan 2016
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    ABSTRACT: Microorganisms produce a great variety of secondary metabolites that feature surface active and bioactive properties. Those possessing an amphiphilc molecular structure are also termed biosurfactant and are of great interest due to their often unique properties. Rouxiella sp. DSM 100043 is a gram negative enterobacter isolated from peat-bog soil and described as a new biosurfactant producing species in this study. Rouxiella sp. produces glycolipids, biosurfactants with a carbohydrate moiety in its structure. This study characterizes the composition of glycolipids with different hydrophobicities that have been produced during cultivation in a bioreactor and been extracted and purified from separated foam. Using two dimensional nuclear magnetic resonance spectroscopy, the hydrophilic moieties are elucidated as glucose with various acylation sites and as talose within the most polar glycolipids. The presence of 3' hydroxy lauroleic acid as well as myristic and myristoleic acid has been detected.
    Full-text · Article · Dec 2015 · AMB Express
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    ABSTRACT: Carboxyl functionalized magnetic cores coated homogeneously with UiO-67 metal–organic frameworks (MOFs) through a liquid phase epitaxy (LPE) process are introduced. Using the as-synthesized core–shell microparticles as stationary phase in HPLC runs with different phenol derivatives, good separation efficiencies can be achieved when applying an acetonitrile/water mobile phase. To understand the advantages and limitations of such MOF based stationary phases in more detail, the experimental elution profiles are compared with simulations from a powerful chromatography modeling software (ChromX) newly developed at the KIT. The simulation results reveal that the affinities of UiO-67 to the tested phenol derivatives strongly differ (2,6-dimethylphenol < benzene-1,3-diol < 2,6-dichlorophenol), while its maximum capacity remains identical for each derivative with 0.14 mol L−1. The uptake kinetics are dominated by intraparticle diffusion while axial dispersion and film diffusion play only minor roles. The pore diffusivities of the phenol derivatives are found to be around 1.3 ⋅ 10−13 m2 s−1. Based on single component data, the successful simulation of multicomponent isocratic pulse experiments is demonstrated. In summary, HPLC runs combined with in-depth modeling are a powerful tool to investigate the interactions between solute molecules and thin MOF films, and to reveal data about affinities, capacities and uptake kinetics.
    Full-text · Article · Oct 2015 · Separation and Purification Technology
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    ABSTRACT: Porous metal-organic frameworks (MOFs) [Cu3(BTC)2(H2O)3]n (also known as HKUST-1; BTC, benzene-1,3,5-tricarboxylic acid) were synthesized as homogeneous shell onto carboxyl functionalized magnetic microparticles through a liquid phase epitaxy (LPE) process. The as-synthesized core-shell HKUST-1 magnetic microparticles composites were characterized by XRD and SEM, and used as stationary phase in high performance liquid chromatography (HPLC). The effects of the unique properties of MOFs onto the chromatographic performance are demonstrated by the experiments. First, remarkable separation of pyridine and bipyridine is achieved, although both molecules show a strong interaction between the Cu-ions in HKUST-1 and the nitrogen atoms in their heterocyles. The difference can be explained due to size exclusion of bipyridine from the well defined pore structure of crystalline HKUST-1. Second, the enormous variety of possible interactions of sample molecules with the metal ions and linkers within MOFs allows for specifically tailored solid phases for challenging separation tasks. For example, baseline separation of three chloroaniline (CLA) isomers tested can be achieved without the need for gradient elution modes. Along with the experimental HPLC runs, in-depth modelling with a recently developed chromatography modelling software (ChromX) was applied and proofs the software to be a powerful tool for exploring the separation potential of thin MOF films. The pore diffusivity of pyridine and CLA isomers within HKUST-1 are found to be around 2.3×10(-15)m(2)s(-1). While the affinity of HKUST-1 to the tested molecules strongly differs, the maximum capacities are in the same range, with 0.37molL(-1) for pyridine and 0.23molL(-1) for CLA isomers, corresponding to 4.0 and 2.5 molecules per MOF unit cell, respectively. Copyright © 2015 Elsevier B.V. All rights reserved.
    No preview · Article · Sep 2015 · Journal of Chromatography A
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    ABSTRACT: Carboxyl functionalized magnetic cores coated homogeneously with UiO-67 metal–organic frameworks (MOFs) through a liquid phase epitaxy (LPE) process are introduced. Using the as-synthesized core–shell microparticles as stationary phase in HPLC runs with different phenol derivatives, good separation efficiencies can be achieved when applying an acetonitrile/water mobile phase. To understand the advantages and limitations of such MOF based stationary phases in more detail, the experimental elution profiles are compared with simulations from a powerful chromatography modeling software (ChromX) newly developed at the KIT. The simulation results reveal that the affinities of UiO-67 to the tested phenol derivatives strongly differ (2,6-dimethylphenol < benzene-1,3-diol < 2,6-dichlorophenol), while its maximum capacity remains identical for each derivative with 0.14 mol L−1. The uptake kinetics are dominated by intraparticle diffusion while axial dispersion and film diffusion play only minor roles. The pore diffusivities of the phenol derivatives are found to be around 1.3 ⋅ 10−13 m2 s−1. Based on single component data, the successful simulation of multicomponent isocratic pulse experiments is demonstrated. In summary, HPLC runs combined with in-depth modeling are a powerful tool to investigate the interactions between solute molecules and thin MOF films, and to reveal data about affinities, capacities and uptake kinetics.
    Full-text · Dataset · Sep 2015
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    Full-text · Dataset · Aug 2015
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    ABSTRACT: OprF is the major outer membrane porin in bacteria belonging to the Pseudomonas genus. In previous studies, we have shown that OprF is required for full virulence expression of the opportunistic pathogen Pseudomonas aeruginosa. Here, we describe molecular insights on the nature of this relationship and report that the absence of OprF leads to increased biofilm formation and production of the Pel exopolysaccharide. Accordingly, the level of c-di-GMP, a key second messenger in biofilm control, is elevated in an oprF mutant. By decreasing c-di-GMP levels in this mutant, both biofilm formation and pel gene expression phenotypes were restored to wild-type levels. We further investigated the impact on two small RNAs, which are associated with the biofilm lifestyle, and found that expression of rsmZ but not of rsmY was increased in the oprF mutant and this occurs in a c-di-GMP-dependent manner. Finally, the extracytoplasmic function (ECF) sigma factors AlgU and SigX displayed higher activity levels in the oprF mutant. Two genes of the SigX regulon involved in c-di-GMP metabolism, PA1181 and adcA (PA4843), were up-regulated in the oprF mutant, partly explaining the increased c-di-GMP level. We hypothesized that the absence of OprF leads to a cell envelope stress that activates SigX and results in a c-di-GMP elevated level due to higher expression of adcA and PA1181. The c-di-GMP level can in turn stimulate Pel synthesis via increased rsmZ sRNA levels and pel mRNA, thus affecting Pel-dependent phenotypes such as cell aggregation and biofilm formation. This work highlights the connection between OprF and c-di-GMP regulatory networks, likely via SigX (ECF), on the regulation of biofilm phenotypes.
    Full-text · Article · Jun 2015 · Frontiers in Microbiology
  • K. Matthies · H. Bitter · N. Deobald · M. Heinle · R. Diedel · U. Obst · G. Brenner-Weiss
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    ABSTRACT: People in rural developing areas often depend on point-of-use water treatment for safe drinking water. A very popular and efficient technology for this is the use of ceramic filters, as promoted by the non-governmental organization Potters for Peace. These filters are already used in many countries worldwide, including Indonesia, where they are manufactured in Bandung, Java by Pelita Indonesia. The filters are made of local clay and combustible material, and coated with silver after firing. However, data available on them are very scarce. The structure, composition, and physico-chemical and microbiological performance of the filter were examined. Pore sizes mostly ranged from 1 to 40 µm and flow rate was about 1.3 L/h. Silver, arsenic and manganese were leaching from the filter in remarkable concentrations. While values for silver were about 0.01–0.02 mg/L, manganese was washed out after a few liters and leaching of arsenic fell below 0.02 mg/L after filtering some liters. With a log reduction of 3–5, efficiency in bacteria reduction was satisfactory in contrast to virus removal which was not sufficient according to the World Health Organization guidelines, with a log reduction below 1.
    No preview · Article · Jun 2015 · Water Practice & Technology
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    ABSTRACT: We propose surface acoustic wave (SAW) resonators as a complementary tool for conditioning film monitoring. Conditioning films are formed by adsorption of inorganic and organic substances on a substrate the moment this substrate comes into contact with a liquid phase. In the case of implant insertion, for instance, initial protein adsorption is required to start wound healing, but it will also trigger immune reactions leading to inflammatory responses. The control of the initial protein adsorption would allow to promote the healing process and to suppress adverse immune reactions. Methods to investigate these adsorption processes are available, but it remains difficult to translate measurement results into actual protein binding events. Biosensor transducers allow user-friendly investigation of protein adsorption on different surfaces. The combination of several transduction principles leads to complementary results, allowing a more comprehensive characterization of the adsorbing layer. We introduce SAW resonators as a novel complementary tool for time-resolved conditioning film monitoring. SAW resonators were coated with polymers. The adsorption of the plasma proteins human serum OPEN ACCESS Sensors 2015, 15 11874 albumin (HSA) and fibrinogen onto the polymer-coated surfaces were monitored. Frequency results were compared with quartz crystal microbalance (QCM) sensor measurements, which confirmed the suitability of the SAW resonators for this application.
    Full-text · Article · May 2015 · Sensors
  • Hartmut Herb · Andreas Gerdes · Gerald Brenner-Weiß
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    ABSTRACT: Silane-based hydrophobic admixtures especially alkyltrialkoxysilanes are used as water repellent agents for the surface protection of concrete. To optimize the structure of alkyltrialkoxysilanes in terms of their performance and their long term durability it is important to understand the chemical reactions taking place between the silicon organic compounds and the materials on which they are applied. For this purpose the characterization of alkyltrialkoxysilanes and their reaction products in concrete is necessary. Therefore we adapted an analytical method based on time-of-flight mass spectrometry (TOF/MS) combined with electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI). Monomeric alkyltrialkoxysilanes could be analyzed by the former method, reaction products which could be identified as Silsesquioxanes (SSOs) by the latter one. The results indicate that ESI-TOF/MS and MALDI-TOF/MS serve as a reliable and convenient tool to characterize monomeric silane-based hydrophobic admixtures as well as their reaction products resulted from hydrolysis and condensation.
    No preview · Article · Apr 2015 · Cement and Concrete Research
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    ABSTRACT: Protein-capture agents are widely used for the detection, immobilization and isolation of proteins and are the foundation for the development of in vitro diagnostic chips. The chemokine CXCL8 is an interesting protein target due to its involvement in the human inflammatory response. We constructed a novel structural model of CXCL8 interaction with its G-protein coupled receptor CXCR1, taking into account previously reported experimental data. From this CXCL8:CXCR1 model complex, the interaction of CXCL8 with residues near the extracellular domains 3 and 4 of CXCR1 were used as a scaffold for the rational design of a peptide capture agent called ‘IL8RPLoops’. A molecular dynamics simulation of IL8RPLoops indicates a stable helical conformation consistent with the CXCR1 structure from which it was derived. CXCL8 capture in fluorescence-based assays on beads and on glass demonstrates that IL8RPLoops is an effective capture agent for CXCL8. Additionally, we found IL8RPLoops to be a potent inhibitor of CXCL8-induced neutrophil migration and CXCL8:CXCR1 association. A theoretical binding model for IL8RPLoops:CXCL8 is proposed, which shows the peptide predominantly interacting with CXCL8 via electrostatic contacts with the ELR motif at the CXCL8 N-terminus.
    No preview · Article · Mar 2015 · RSC Advances
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    H Yan · V Solozobova · P Zhang · O Armant · B Kuehl · G Brenner-Weiss · C Blattner
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    ABSTRACT: Since it was found that p53 is highly expressed in murine embryonic stem cells, it remained a mystery whether p53 is active in this cell type. We show that a significant part of p53 is localised in the nucleus of murine embryonic stem cells and that the majority of this nuclear p53 is bound to DNA. According to its nuclear localisation, we show that p53 alters the transcriptional program of stem cells. Nevertheless, the anti-proliferative activity of p53 is compromised in stem cells, and this control is due, at least in part, to the high amount of MdmX that is present in embryonic stem cells and bound to p53. Instead of the anti-proliferative activity that p53 has in differentiated cells, p53 controls transcription of pro-proliferative genes in embryonic stem cells including c-myc and c-jun. The impeded anti-proliferative activity of p53 and the induction of certain proto-oncogenes by p53 in murine embryonic stem cells can explain why stem cells proliferate efficiently despite having high levels of p53.
    Full-text · Article · Feb 2015 · Cell Death & Disease
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    ABSTRACT: Pseudomonas aeruginosa is an opportunistic human pathogen which is able to sense and adapt to numerous environmental stimuli by the use of transcriptional regulators including two-component regulatory systems. In this study, we demonstrate that the sensor kinase PA4398 is involved in the regulation of swarming motility and biofilm formation in P. aeruginosa PA14. The respective PA4398(-) mutant strain was considerably impaired in swarming motility while biofilm formation was increased by approximately two-fold. The PA4398(-) mutant did not show any changes in growth rate, rhamnolipid synthesis or the production of the Pel exopolysaccharide, but exhibited a 50 % increase in the intracellular second messenger cyclic-di-GMP compared to wild-type cells. The role of PA4398 in gene regulation was investigated by comparing the PA4398(-) mutant to wild-type using microarray analysis, demonstrating 64 genes were up- or down-regulated by more than 1.5-fold (p < 0.05) under swarming conditions. In addition, more sensitive real-time PCR studies were performed on genes known to be involved in c-di-GMP metabolism. Among the dysregulated were several genes involved in synthesis and degradation of c-di-GMP as well as in the biosynthesis, transport or function of the iron-scavenging siderophores pyoverdine and pyochelin consistent with the observed swarming phenotype. By analyzing additional mutants of selected pyoverdine and pyochelin-related genes, we were able to show that not only pvdQ, but also pvdR, fptA, pchA, pchD and pchH are essential for normal swarming behavior of P. aeruginosa PA14 and may also contribute to the swarming deficient phenotype of the PA4398(-) mutant in addition to elevated c-di-GMP levels. Copyright © 2014, American Society for Microbiology. All Rights Reserved.
    Preview · Article · Dec 2014 · Applied and Environmental Microbiology
  • Carolin Richter · Thomas Simon · Iris Asen · Gerald Brenner-Weiss · Jürgen Hubbuch
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    ABSTRACT: The autoantigen U1-68/70 K is the dominant diagnostic marker in Mixed Connective Tissue Disease (MCTD) that until recently could not be expressed in its full-length form [Northemann et al., 1995]. Using cell-free expression screening, we successfully produced the snRNP protein U1-68/70 K in a soluble full-length form in Escherichia coli cells. The protein length and identity was determined by Western Blot and MS/MS analysis. Additionally, its reactivity in the autoimmune diagnostic was confirmed. Establishment of a cell-free expression system for this protein was important for further elucidation of protein expression properties such as the cDNA construct, expression temperature and folding properties; these parameters can now be determined in a fast and resource-conserving manner.
    No preview · Article · Dec 2014 · Protein Expression and Purification
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    ABSTRACT: Software routine allowing identification of Software routine allowing identification of extracellular extracellular biofilm biofilm proteins proteins involved in cell adhesion based on data from QCM involved in cell adhesion based on data from QCM-D/MALDI experiments D/MALDI experiments Department of microbiology of natural and technical surfaces, Institute of Functional Interfaces (IFG) CONCLUSIONS As demonstrated by the experiments the coupling of QCM-D with high resolution mass spectrometry (MALDI-ToF/MS) is a powerful tool for analyzing conditioning films of supernatant of P. aeruginosa. RESULTS AND DISCUSSION We were able to identify several intracellular as well as extracellular proteins including adhesion proteins to be involved in conditioning film formation in all three supernatants of P. aeruginosa PAO1 by MALDI-ToF/MS and to ensure their correct identification by MALDI-ToF/MSMS. INTRODUCTION The first step in the settelment of planctonic bacterial from a liquid medium onto a solid surface is the adsorption of substances contained in the medium onto the surface. The layer of adsorbed substances, e.g. proteins, polysaccharides, etc. is called conditioning film.
    No preview · Conference Paper · Sep 2014
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    ABSTRACT: Software routine allowing identification of Software routine allowing identification of extracellular extracellular biofilm biofilm proteins proteins involved in cell adhesion based on data from QCM involved in cell adhesion based on data from QCM-D/MALDI experiments D/MALDI experiments Department of microbiology of natural and technical surfaces, Institute of Functional Interfaces (IFG) CONCLUSIONS As demonstrated by the experiments the coupling of QCM-D with high resolution mass spectrometry (MALDI-ToF/MS) is a powerful tool for analyzing conditioning films of supernatant of P. aeruginosa. RESULTS AND DISCUSSION We were able to identify several intracellular as well as extracellular proteins including adhesion proteins to be involved in conditioning film formation in all three supernatants of P. aeruginosa PAO1 by MALDI-ToF/MS and to ensure their correct identification by MALDI-ToF/MSMS. INTRODUCTION The first step in the settelment of planctonic bacterial from a liquid medium onto a solid surface is the adsorption of substances contained in the medium onto the surface. The layer of adsorbed substances, e.g. proteins, polysaccharides, etc. is called conditioning film.
    Full-text · Conference Paper · Sep 2014
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    ABSTRACT: Actinomycetales are known to produce various secondary metabolites including products with surface-active and emulsifying properties known as biosurfactants. In this study, the nonpathogenic actinomycetes Tsukamurella spumae and Tsukamurella pseudospumae are described as producers of extracellular trehalose lipid biosurfactants when grown on sunflower oil or its main component glyceryltrioleate. Crude extracts of the trehalose lipids were purified using silica gel chromatography. The structure of the two trehalose lipid components (TL A and TL B) was elucidated using a combination of matrix-assisted laser desorption/ionization time-of-flight/time-of-flight/tandem mass spectroscopy (MALDI-ToF-ToF/MS/MS) and multidimensional NMR experiments. The biosurfactants were identified as 1-α-glucopyranosyl-1-α-glucopyranosid carrying two acyl chains varying of C4 to C6 and C16 to C18 at the 2' and 3' carbon atom of one sugar unit. The trehalose lipids produced demonstrate surface-active behavior and emulsifying capacity. Classified as risk group 1 organisms, T. spumae and T. pseudospumae hold potential for the production of environmentally friendly surfactants.
    No preview · Article · Aug 2014 · Applied Microbiology and Biotechnology
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    ABSTRACT: In the fields of surgery and regenerative medicine, it is crucial to understand the interactions of proteins with the biomaterials used as implants. Protein adsorption directly influences cell-material interactions in vivo and, as a result, regulates e.g. cell adhesion on the surface of the implant. Therefore, the development of suitable analytical techniques together with well-defined model-systems allowing for the detection, characterization and quantification of protein adsorbates is essential. In this study, a protocol for the deposition of highly stable, thin gelatin-based films on various substrates has been developed. The hydrogel films were characterized morphologically and chemically. Due to the obtained low thickness of the hydrogel layer, this setup allowed for a quantitative study on the interaction of human proteins (albumin and fibrinogen) with the hydrogel by Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D). This technique enables the determination of adsorbant mass and changes in the shear modulus of the hydrogel layer upon adsorption of human proteins. Furthermore, Secondary Ion Mass Spectrometry and principal component analysis was applied to monitor the changed composition of the topmost adsorbate layer. This approach opens interesting perspectives for a sensitive screening of viscoelastic biomaterials that could be used for regenerative medicine.
    No preview · Article · Jun 2014 · Biomacromolecules
  • Gertrud M Hänsch · Birgit Prior · Gerald Brenner-Weiss · Ursula Obst · Joerg Overhage
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    ABSTRACT: Cross-talk between bacteria and mammalian cells is increasingly recognized as an important factor, especially during chronic infections. In particular, the interaction of extracellular bacterial signaling molecules with cells of the innate immune response is of special interest. In this context, we investigated whether the Pseudomonas quinolone signal (PQS) which is a quorum sensing molecule produced by bacteria and participates in biofilm formation and virulence has any influence on polymorphonuclear neutrophils (PMN), the cells of the "first line defense" against bacterial infections. We found that PQS did not enhance the bactericidal activity of PMN and did not induce apoptosis at concentrations up to 100 µM. However, PQS stimulated chemotaxis of PMN in doses of 10-100 µM. This PQS-dependent chemotaxis could be inhibited with SB203580 which blocks MAPkinase p38, suggesting a signaling pathway similar to AHL-12 induction. Using bacterial cell culture supernantants of Pseudomonas aeruginosa wild-type cells and a PQS-deficient mutant strain support the in vivo relevance of these findings. Since PQS is produced in the early phase of biofilm formation, PMN infiltration could be timely enough to eradicate bacteria before biofilm formation is completed, which confers the bacteria with a relative resistance to host defense mechanisms.
    No preview · Article · May 2014 · Journal of Applied Biomaterials and Fundamental Materials
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    ABSTRACT: Despite intense research on biological and biomedical applications of nanoparticles, our understanding of their basic interactions with the biological environment is still incomplete. Systematic variation of the physicochemical properties of the nanoparticles is widely seen as a promising strategy to obtain further insights. In view of the key role of the protein adsorption layer forming on nanoparticles in contact with biofluids, we systematically varied the surface charge of proteins adsorbing onto nanoparticles by chemical modification so as to examine the effect of Coulomb forces in modulating nano-bio interactions. We chose human serum albumin (HSA) as a model protein and ultra-small, negatively charged fluorescent gold nanoclusters (AuNCs) as model nanoparticles. By using fluorescence and CD spectroscopies, we measured binding affinities and structural changes upon binding of the HSA variants. The strengths of the protein-nanoparticle interactions were found to change substantially upon modifying the surface charge of HSA. Furthermore, by using inductively coupled plasma optical emission spectroscopy, confocal fluorescence microscopy, scanning transmission electron microscopy and cell viability assays, we observed that cellular interactions of the AuNCs, including their adherence to cell membranes, uptake efficiency and cytotoxicity, depended markedly on the different surface charges of the HSA variants adsorbed onto the nanoparticles. These results illustrate vividly that the cellular responses to nanoparticle exposure depend on the specific properties of the proteins that adsorb onto nanoparticles from biofluids.
    Full-text · Article · Apr 2014 · Advanced Materials Interfaces