This short review highlights the role of reaction engineering as a tool for bioprocess development. Selected examples are discussed that demonstrate the need to understand thermodynamic and kinetic ...properties of the reaction system in order to identify potential bottlenecks. For coupled
enzyme systems and reaction cascades modelling as well as selection of suitable reactor configurations is discussed. For the problem of overcoming product inhibition examples are given, followed by selected examples for in situ product removal. Finally, two reactor concepts for oxidation
reactions requiring oxygen are briefly presented.
The ionic liquid (IL) Ammoeng110trade mark sign contains cations with oligoethyleneglycol units and was found to be highly effective for the formation of aqueous two-phase systems (ATPS) that can be ...used for the biocompatible purification of active enzymes. Above critical concentrations of the IL and an inorganic salt in aqueous solution, phase separation takes place resulting in the formation of an IL-enriched upper and a salt-enriched lower phase. For the optimization of the composition of IL-based ATPS with regard to the extraction of catalytically active enzymes, the Box-Wilson method of experimental design was successfully applied; IL-based ATPS proved to be suitable for the purification and stabilization of two different alcohol dehydrogenases (from Lactobacillus brevis and a thermophilic bacterium). Both enzymes were enriched in the IL-containing upper phase resulting in an increase of specific activity by a factor of 2 and 4 respectively. Furthermore, the presence of IL within the system provided the opportunity to combine the extraction process with the performance of enzyme-catalyzed reactions. The IL was found to exhibit a stability improving effect on both enzymes and a solubility enhancing effect on hydrophobic substrates. Thus the conversion and volumetric productivity of ADH catalyzed reduction of acetophenone could be increased significantly. Biotechnol. Bioeng. 2008;99: 1416-1424.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
3.
Industrial biotechnology-the future of green chemistry? Wenda, Stefanie; Illner, Sabine; Mell, Annett ...
Green chemistry : an international journal and green chemistry resource : GC,
01/2011, Volume:
13, Issue:
11
Journal Article
Peer reviewed
Biocatalysis fulfils many key criteria of green chemistry, but this raises the question: how efficient are such production methods and how important is biotechnology for greener industrial chemistry ...today? This review summarizes the advantages, disadvantages and potential uses of biocatalysis to undertake greener chemistry. By addressing the obstacles of biocatalytic approaches, it will be demonstrated that continuous improvement is required to overcome existing limitations. To illustrate the state of the art in the use of enzymes and microorganisms, representative examples of industrial chemistry are discussed and evaluated in this article. Several biocatalytic processes are compared to their chemical alternatives. Finally, future trends for the biocatalytic reductions of amides and the asymmetric hydrogenation of olefins are discussed.
The scope and limitations of industrial biotechnology are discussed in its contribution towards greener chemistry.
Polymers are commonly used in medical device manufacturing, e.g. for drug delivery systems, bone substitutes and stent coatings. Especially hydrogels exhibit very promising properties in this field. ...Hence, the development of new hydrogel systems for customized application is of great interest, especially regarding the swelling behavior and mechanical properties as well as the biocompatibility. The aim of this work was the preparation and investigation of various polyelectrolyte and poly-ionic liquid based hydrogels accessible by radical polymerization. The obtained polymers were covalently crosslinked with N,N'-methylenebisacrylamide (MBAA) or different lengths of poly(ethyleneglycol)diacrylate (PEGDA). The effect of different crosslinker-to-monomer ratios has been examined. In addition to the compression curves and the maximum degree of swelling, the biocompatibility with L929 mouse fibroblasts of these materials was determined in direct cell seeding experiments and the outcome for the different hydrogels was compared.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The polysaccharide laminarin (β-1,3-glucan) is used as a long-term carbon storage compound in brown algae. This chemical storage form of carbon enables perennial brown algae in seasonally fluctuating ...ecosystems to uncouple growth from photosynthesis, i.e., most of these plants grow as seasonal anticipators in winter based on remobilization of laminarin, while in summer, growth typically ceased to fill up the storage pool. Because of this high ecological relevance, a reliable and precise method for determination and quantification of laminarin is needed. Therefore, a simple, efficient, cold water extraction method coupled to a new quantitative liquid chromatography-mass spectrometrical method (LC-MS) was developed. Laminarin was determined in 9 out of 12 brown algal species, and its expected typical molar mass distribution of 2000–7000 Da was confirmed. Furthermore, laminarin consisted of a complex mixture of different chemical forms, since 15 chemical laminarin species with distinct molecular weights were measured in 9 species of brown algae. Differences in chain length and number of laminarin species seem to be species specific and hence may indicate some chemotaxonomic value. Laminarin concentrations in the algal tissues ranged from 0.03 to 0.86 % dry weight (DW). The direct chemical characterization and quantification of laminarin by LC-MS represents a powerful method to verify the biochemical and ecological importance of laminarin for brown algae.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Controlled initiation of biochemical events and in particular of protein activity is a powerful tool in biochemical research. Specifically, optical trigger signals are an attractive approach for ...remote control of enzyme activity. We present a method for generating optical control of enzyme activity applicable to a widespread range of enzymes. The approach is based on short laser pulses as optical “switches” introducing an instantaneous change of the pH-value for activation of protein function. The pH-jump is induced by proton release from 2-nitrobenzaldehyde. Reaction conditions were chosen to yield a pH-jump of almost 3 units on switching from inactive to active conditions for the enzyme. In this experimental setup, irradiation can be realized without any loss of enzyme activity. Following this change in pH-value, a controlled activation of hydrolytic activity of acid phosphatase is successfully demonstrated. This application provides a general method for photocontrol of enzymatic function for proteins having a significant pH-profile. The kinetic data for the substrate 6-chloro-8-fluoro-4-methylumbelliferone phosphate are determined.
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The volatile nature of ionic liquids: Ionic liquids are recognized as “green” solvents because of their essentially null volatility. Ironically, it is the low vapor pressure, the large enthalpy of ...vaporization, and the high boiling point of ionic liquids that make it difficult to study their macroscopic behavior at a molecular level. Recent studies, however, have shed light on their thermochemical properties (picture: snapshot of an ionic liquid from molecular dynamics simulations).
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Extraction of catalytically active biomolecules using ionic liquid-based aqueous two-phase systems (IL-based ATPS) composed of the IL Ammoeng™ 110 and K
2HPO
4/KH
2PO
4 represents a powerful tool for ...the integration of several process steps into one unit operation within downstream processing. The technique can be used in order to combine the purification of active enzymes with the performance of enzyme-catalysed reactions. However, a fundamental understanding of the driving forces which are involved in the partitioning of proteins between the two phases is still lacking. By investigating the distribution of four model proteins at varying system characteristics of the IL-based ATPS, we found a combination of different interactions between the proteins and the ionic liquid to be responsible for the enrichment within the IL-containing upper phase. Among these, the proteins’ charge as well as the molecular weight is of major importance. Therefore, we propose the electrostatic interaction between the charged amino acid residues at a protein's surface and the positively charged IL-cation to be the main driving force of the extraction process. Based on these findings, a model for describing protein partitioning in IL-based ATPS was established and employed for predicting the partition coefficient of two further model proteins, pepsin and hemoglobin.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Hydrogels are one of the emerging classes of materials in current research. Besides their numerous applications in the medical sector as a drug delivery system or in tissue replacement, they are also ...suitable as irrigation components or as immobilization matrices in catalysis. For optimal application of these compounds, knowledge of the swelling properties and the diffusion mechanisms occurring in the gels is mandatory. This study is focused on hydrogels synthesized by radical polymerization of imidazolium-based ionic liquids. Both the swelling and diffusion behavior of these hydrogels were investigated via gravimetric swelling as well as sorption experiments implemented in water, ethanol, n-heptane, and tetrahydrofuran. In water and ethanol, strong swelling was observed while the transport mechanism deviated from Fickian-type behavior. By varying the counterion and the chain length of the cation, their influences on the processes were observed. The calculation of the diffusion coefficients delivered values in the range of 10−10 to 10−12 m2 s−1. The gravimetric results were supported by apparent diffusion coefficients measured through diffusion-weighted magnetic resonance imaging. A visualization of the water diffusion front within the hydrogel should help to further elucidate the diffusion processes in the imidazolium-based hydrogels.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
The very low vapor pressure of ionic liquids is challenging to measure. At elevated temperatures the liquids might start to decompose, and at relatively low temperatures the vapor pressure becomes ...too low to be measured by conventional methods. In this work we developed a highly sensitive method for mass loss determination at temperatures starting from 350 K. This technique is based on an alternating current calorimeter equipped with a chip sensor that consists of a free-standing SiN
x
-membrane (thickness <1 μm) and a measuring area with lateral dimensions of the order of 1 mm. A small droplet (diameter
ca.
600 μm) of an ionic liquid is vaporized isothermally from the chip sensor in a vacuum-chamber. The surface-to-volume-ratio of such a droplet is large and the relative mass loss due to evaporation is therefore easy to monitor by the changing heat capacity (J K
−1
) of the remaining liquid. The vapor pressure is determined from the measured mass loss rates using the Langmuir equation. The method was successfully tested for the determination of the vapor pressure and the vaporization enthalpy of an archetypical ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImNTf
2
). The data set created in this way in an extremely broad temperature range from 358 K to 780 K has allowed the estimation of the boiling temperature of EMImNTf
2
. The value (1120 ± 50) K should be considered as the first reliable boiling point of the archetypical ionic liquid obtained from experimental vapor pressures measured in the most possible close proximity to the normal boiling temperature.
A new method for the determination of vaporization enthalpies of ionic liquids using mass loss rates from AC-chip-calorimetry at low temperatures and a reliable estimate of the boiling temperature of EMImNTf
2
(
T
b
= (1120 ± 50) K).
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