51
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Gourdin-Bertin S, Dufrêche JF, Duvail M, Zemb T. Microemulsion as Model to Predict Free Energy of Transfer of Electrolyte in Solvent Extraction. SOLVENT EXTRACTION AND ION EXCHANGE 2021. [DOI: 10.1080/07366299.2021.1953259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
| | | | - Magali Duvail
- ICSM, CEA, Univ Montpellier, CNRS, ENSCM, Marcoule, France
| | - Thomas Zemb
- ICSM, CEA, Univ Montpellier, CNRS, ENSCM, Marcoule, France
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52
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Uematsu Y. Electrification of water interface. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33. [PMID: 34280896 DOI: 10.1088/1361-648x/ac15d5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 07/19/2021] [Indexed: 05/04/2023]
Abstract
The surface charge of a water interface determines many fundamental processes in physical chemistry and interface science, and it has been intensively studied for over a hundred years. We summarize experimental methods to characterize the surface charge densities developed so far: electrokinetics, double-layer force measurements, potentiometric titration, surface-sensitive nonlinear spectroscopy, and surface-sensitive mass spectrometry. Then, we elucidate physical ion adsorption and chemical electrification as examples of electrification mechanisms. In the end, novel effects on surface electrification are discussed in detail. We believe that this clear overview of state of the art in a charged water interface will surely help the fundamental progress of physics and chemistry at interfaces in the future.
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Affiliation(s)
- Yuki Uematsu
- Department of Physics, Kyushu University, Fukuoka 819-0395, Japan
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53
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Holt C. A quantitative calcium phosphate nanocluster model of the casein micelle: the average size, size distribution and surface properties. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2021; 50:847-866. [PMID: 33866398 DOI: 10.1007/s00249-021-01533-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/22/2021] [Accepted: 03/28/2021] [Indexed: 10/21/2022]
Abstract
Caseins (αS1, αS2, β and κ) are the main protein fraction of bovine milk. Together with nanoclusters of amorphous calcium phosphate (CaP) and divalent cations, they combine to form a polydisperse distribution of particles called casein micelles. A casein micelle model is proposed which is consistent with the way in which intrinsically disordered proteins interact through predominantly polar, short, linear, motifs. Using the model, an expression is derived for the size distribution of casein micelles formed when caseins bind to the CaP nanoclusters and the complexes further associate with each other and the remaining mixture of free caseins. The result is a refined coat-core model in which the core is formed mainly by the nanocluster complexes and the coat is formed exclusively by the free caseins. Example calculations of the size distribution and surface composition of an average bovine milk are compared with experiment. The average size, size distribution and surface composition of the micelles is shown to depend on the affinity of the nanocluster complexes for each other in competition with their affinity for free caseins, and on the concentrations of free caseins, calcium ions and other salts in the continuous phase.
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Affiliation(s)
- Carl Holt
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow, G12 8QQ, UK.
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54
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Špadina M, Dourdain S, Rey J, Bohinc K, Pellet-Rostaing S, Dufrêche JF, Zemb T. How acidity rules synergism and antagonism in liquid–liquid extraction by lipophilic extractants—Part II: application of the ienaic modelling. SOLVENT EXTRACTION AND ION EXCHANGE 2021. [DOI: 10.1080/07366299.2021.1899614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- M. Špadina
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, France
- Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - S. Dourdain
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, France
| | - J. Rey
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, France
| | - K. Bohinc
- Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | | | | | - T. Zemb
- ICSM, Univ Montpellier, CEA, CNRS, ENSCM, Marcoule, France
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55
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Johnson EC, Gresham IJ, Prescott SW, Nelson A, Wanless EJ, Webber GB. The direction of influence of specific ion effects on a pH and temperature responsive copolymer brush is dependent on polymer charge. POLYMER 2021. [DOI: 10.1016/j.polymer.2020.123287] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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56
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Leppin C, Peschel A, Meyer FS, Langhoff A, Johannsmann D. Kinetics of viscoelasticity in the electric double layer following steps in the electrode potential studied by a fast electrochemical quartz crystal microbalance (EQCM). Analyst 2021; 146:2160-2171. [DOI: 10.1039/d0an01965h] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A fast EQCM measures the kinetics of the viscosity changes inside the double layer following voltage jumps.
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Affiliation(s)
- Christian Leppin
- Institute of Physical Chemistry
- Clausthal University of Technology
- D-38678 Clausthal-Zellerfeld
- Germany
| | - Astrid Peschel
- Institute of Physical Chemistry
- Clausthal University of Technology
- D-38678 Clausthal-Zellerfeld
- Germany
| | - Frederick Sebastian Meyer
- Institute of Physical Chemistry
- Clausthal University of Technology
- D-38678 Clausthal-Zellerfeld
- Germany
| | - Arne Langhoff
- Institute of Physical Chemistry
- Clausthal University of Technology
- D-38678 Clausthal-Zellerfeld
- Germany
| | - Diethelm Johannsmann
- Institute of Physical Chemistry
- Clausthal University of Technology
- D-38678 Clausthal-Zellerfeld
- Germany
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57
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Mehringer J, Hofmann E, Touraud D, Koltzenburg S, Kellermeier M, Kunz W. Salting-in and salting-out effects of short amphiphilic molecules: a balance between specific ion effects and hydrophobicity. Phys Chem Chem Phys 2021; 23:1381-1391. [DOI: 10.1039/d0cp05491g] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Salting-in or salting-out tendencies depend on a balance between headgroup-specific ion effects and the hydrophobicity of the tail.
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Affiliation(s)
- Johannes Mehringer
- Institute of Theoretical and Physical Chemistry
- University of Regensburg
- 93053 Regensburg
- Germany
| | - Evamaria Hofmann
- Institute of Theoretical and Physical Chemistry
- University of Regensburg
- 93053 Regensburg
- Germany
| | - Didier Touraud
- Institute of Theoretical and Physical Chemistry
- University of Regensburg
- 93053 Regensburg
- Germany
| | | | | | - Werner Kunz
- Institute of Theoretical and Physical Chemistry
- University of Regensburg
- 93053 Regensburg
- Germany
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58
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Shukla SK, Mikkola JP. Use of Ionic Liquids in Protein and DNA Chemistry. Front Chem 2020; 8:598662. [PMID: 33425856 PMCID: PMC7786294 DOI: 10.3389/fchem.2020.598662] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 12/01/2020] [Indexed: 12/12/2022] Open
Abstract
Ionic liquids (ILs) have been receiving much attention as solvents in various areas of biochemistry because of their various beneficial properties over the volatile solvents and ILs availability in myriad variants (perhaps as many as 108) owing to the possibility of paring one cation with several anions and vice-versa as well as formulations as zwitterions. Their potential as solvents lies in their tendency to offer both directional and non-directional forces toward a solute molecule. Because of these forces, ionic liquids easily undergo intermolecular interactions with a range of polar/non-polar solutes, including biomolecules such as proteins and DNA. The interaction of genomic species in aqueous/non-aqueous states assists in unraveling their structure and functioning, which have implications in various biomedical applications. The charge density of ionic liquids renders them hydrophilic and hydrophobic, which retain intact over long-range of temperatures. Their ability in stabilizing or destabilizing the 3D-structure of a protein or the double-helical structure of DNA has been assessed superior to the water and volatile organic solvents. The aptitude of an ion in influencing the structure and stability of a native protein depends on their ranking in the Hofmeister series. However, at several instances, a reverse Hofmeister ordering of ions and specific ion-solute interaction has been observed. The capability of an ionic liquid in terms of the tendency to promote the coiling/uncoiling of DNA structure is noted to rely on the basicity, electrostatic interaction, and hydrophobicity of the ionic liquid in question. Any change in the DNA's double-helical structure reflects a change in its melting temperature (T m), compared to a standard buffer solution. These changes in DNA structure have implications in biosensor design and targeted drug-delivery in biomedical applications. In the current review, we have attempted to highlight various aspects of ionic liquids that influence the structure and properties of proteins and DNA. In short, the review will address the issues related to the origin and strength of intermolecular interactions, the effect of structural components, their nature, and the influence of temperature, pH, and additives on them.
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Affiliation(s)
- Shashi Kant Shukla
- Technical Chemistry, Department of Chemistry, Chemical-Biological Centre, Umeå University, Umeå, Sweden
| | - Jyri-Pekka Mikkola
- Technical Chemistry, Department of Chemistry, Chemical-Biological Centre, Umeå University, Umeå, Sweden
- Industrial Chemistry and Reaction Engineering, Department of Chemical Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland
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59
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Neal JF, Saha A, Zerkle MM, Zhao W, Rogers MM, Flood AH, Allen HC. Molecular Recognition and Hydration Energy Mismatch Combine To Inform Ion Binding Selectivity at Aqueous Interfaces. J Phys Chem A 2020; 124:10171-10180. [DOI: 10.1021/acs.jpca.0c09568] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Jennifer F. Neal
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Ankur Saha
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Mia M. Zerkle
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Wei Zhao
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Mickey M. Rogers
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Amar H. Flood
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Heather C. Allen
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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60
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Bruce EE, Okur HI, Stegmaier S, Drexler CI, Rogers BA, van der Vegt NFA, Roke S, Cremer PS. Molecular Mechanism for the Interactions of Hofmeister Cations with Macromolecules in Aqueous Solution. J Am Chem Soc 2020; 142:19094-19100. [PMID: 33124825 DOI: 10.1021/jacs.0c07214] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ion identity and concentration influence the solubility of macromolecules. To date, substantial effort has been focused on obtaining a molecular level understanding of specific effects for anions. By contrast, the role of cations has received significantly less attention and the underlying mechanisms by which cations interact with macromolecules remain more elusive. To address this issue, the solubility of poly(N-isopropylacrylamide), a thermoresponsive polymer with an amide moiety on its side chain, was studied in aqueous solutions with a series of nine different cation chloride salts as a function of salt concentration. Phase transition temperature measurements were correlated to molecular dynamics simulations. The results showed that although all cations were on average depleted from the macromolecule/water interface, more strongly hydrated cations were able to locally accumulate around the amide oxygen. These weakly favorable interactions helped to partially offset the salting-out effect. Moreover, the cations approached the interface together with chloride counterions in solvent-shared ion pairs. Because ion pairing was concentration-dependent, the mitigation of the dominant salting-out effect became greater as the salt concentration was increased. Weakly hydrated cations showed less propensity for ion pairing and weaker affinity for the amide oxygen. As such, there was substantially less mitigation of the net salting-out effect for these ions, even at high salt concentrations.
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Affiliation(s)
- Ellen E Bruce
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, D-64287 Darmstadt, Germany
| | - Halil I Okur
- Department of Chemistry, and National Nanotechnology Research Center (UNAM), Bilkent University, 06800 Ankara, Turkey.,Laboratory for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Sina Stegmaier
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, D-64287 Darmstadt, Germany
| | | | | | - Nico F A van der Vegt
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, D-64287 Darmstadt, Germany
| | - Sylvie Roke
- Laboratory for fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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61
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Katana B, Takács D, Csapó E, Szabó T, Jamnik A, Szilagyi I. Ion Specific Effects on the Stability of Halloysite Nanotube Colloids-Inorganic Salts versus Ionic Liquids. J Phys Chem B 2020; 124:9757-9765. [PMID: 33076658 PMCID: PMC7660744 DOI: 10.1021/acs.jpcb.0c07885] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 10/09/2020] [Indexed: 11/30/2022]
Abstract
Charging and aggregation processes were studied in aqueous dispersions of halloysite nanotubes (HNTs) in the presence of monovalent inorganic electrolytes and ionic liquid (IL) constituents. The same type of co-ion (same sign of charge as HNT) was used in all systems, while the type of counterions (opposite sign of charge as HNT) was systematically varied. The affinity of the inorganic cations to the HNT surface influenced their destabilizing power leading to an increase in the critical coagulation concentration (CCC) of HNT dispersions in the Cs+ < K+ < Na+ order. This trend agrees with the classical Hofmeister series for negatively charged hydrophobic surfaces. For the IL cations, the CCCs increased in the order BMPY+ < BMPIP+ < BMPYR+ < BMIM+. An unexpectedly strong adsorption of BMPY+ cations on the HNT surface was observed giving rise to charge neutralization and reversal of the oppositely charged outer surface of HNT. The direct Hofmeister series was extended with these IL cations. The main aggregation mechanism was rationalized within the classical theory developed by Derjaguin, Landau, Verwey, and Overbeek, while ion specific effects resulted in remarkable variation in the CCC values. The results unambiguously proved that the hydration level of the surface and the counterions plays a crucial role in the formation of the ionic composition at the solid-liquid interface and consequently, in the colloidal stability of the HNT particles in both inorganic salt and IL solutions.
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Affiliation(s)
- Bojana Katana
- MTA-SZTE
Lendület Biocolloids Research Group and Interdisciplinary Excellence Center,
Department of Physical Chemistry and Materials Science, University of Szeged, H-6720 Szeged, Hungary
| | - Dóra Takács
- MTA-SZTE
Lendület Biocolloids Research Group and Interdisciplinary Excellence Center,
Department of Physical Chemistry and Materials Science, University of Szeged, H-6720 Szeged, Hungary
| | - Edit Csapó
- MTA-SZTE
Lendület Biocolloids Research Group and Interdisciplinary Excellence Center,
Department of Physical Chemistry and Materials Science, University of Szeged, H-6720 Szeged, Hungary
| | - Tamás Szabó
- MTA-SZTE
Lendület Biocolloids Research Group and Interdisciplinary Excellence Center,
Department of Physical Chemistry and Materials Science, University of Szeged, H-6720 Szeged, Hungary
| | - Andrej Jamnik
- Faculty
of Chemistry and Chemical Technology, University
of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Istvan Szilagyi
- MTA-SZTE
Lendület Biocolloids Research Group and Interdisciplinary Excellence Center,
Department of Physical Chemistry and Materials Science, University of Szeged, H-6720 Szeged, Hungary
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62
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Yoshida C, Murakami M, Niwa A, Takeya M, Osanai T. Efficient extraction and preservation of thermotolerant phycocyanins from red alga Cyanidioschyzon merolae. J Biosci Bioeng 2020; 131:161-167. [PMID: 33109478 DOI: 10.1016/j.jbiosc.2020.09.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 09/21/2020] [Accepted: 09/29/2020] [Indexed: 01/10/2023]
Abstract
C-Phycocyanin (PC) is a protein used commercially as a natural blue pigment produced by cyanobacteria, cryptophytes, and rhodophytes. Although it is industrially synthesized from the cyanobacterium Arthrospira platensis, PC requires high levels of energy for its extraction, which involves freezing of cells. However, as a protein, PC is easily denatured at extreme temperatures. In this study, we extracted PC from the red alga Cyanidioschyzon merolae, denoted as CmPC, and found that this protein was tolerant to high temperatures and acidic pH. CmPC was extracted by suspending cells in water mixed with various salts and organic acids without freeze-drying or freeze-thaw. The stability of CmPC varied with salt concentration and was destabilized by organic acids. Our results indicate that C. merolae is a potential candidate for PC production with thermotolerant properties.
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Affiliation(s)
- Chihiro Yoshida
- School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Miyabi Murakami
- School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Anna Niwa
- School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Masahiro Takeya
- School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan
| | - Takashi Osanai
- School of Agriculture, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki, Kanagawa 214-8571, Japan.
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63
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Budroni MA, Rossi F, Marchettini N, Wodlei F, Lo Nostro P, Rustici M. Hofmeister Effect in Self-Organized Chemical Systems. J Phys Chem B 2020; 124:9658-9667. [PMID: 32989990 DOI: 10.1021/acs.jpcb.0c06956] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We studied the effect of spectator ions in the prototype of far-from-equilibrium self-organized chemical systems, the Belousov-Zhabotinsky (BZ) reaction. In particular, we investigated the specific ion effect of alkali metal cations, connoted for their kosmotropic and chaotropic properties. By means of combined experimental and numerical approaches, we could show a neat and robust evidence for the Hofmeister effect in this system. Spectator cations induce a marked increment of the induction period that preludes regular oscillations and decrease the oscillation amplitude following the sequence Li+ < Na+ ≪ K+ ∼ Cs+. These ions affect the system kinetics by interfering in the interaction between the oxidized form of the catalyst and the organic substrate, responsible for resetting the BZ system to pre-autocatalytic (reduced) conditions. The specific ion effect on these key reactive steps is systematically characterized and correlated with different parameters which describe the interaction of the cations with the solvent.
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Affiliation(s)
- Marcello A Budroni
- Department of Chemistry and Pharmacy, University of Sassari, Sassari (SS) 07100, Italy
| | - Federico Rossi
- Department of Earth, Environmental and Physical Sciences-DEEP Sciences, University of Siena, Siena (SI) 53100, Italy
| | - Nadia Marchettini
- Department of Earth, Environmental and Physical Sciences-DEEP Sciences, University of Siena, Siena (SI) 53100, Italy
| | - Florian Wodlei
- Department of Chemistry and Pharmacy, University of Sassari, Sassari (SS) 07100, Italy
| | - Pierandrea Lo Nostro
- Department of Chemistry, University of Florence, Sesto Fiorentino (FI) 50019, Italy
| | - Mauro Rustici
- Department of Chemistry and Pharmacy, University of Sassari, Sassari (SS) 07100, Italy
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64
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Baghalabadi V, Doucette AA. Mass spectrometry profiling of low molecular weight proteins and peptides isolated by acetone precipitation. Anal Chim Acta 2020; 1138:38-48. [PMID: 33161983 DOI: 10.1016/j.aca.2020.08.057] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/25/2020] [Accepted: 08/28/2020] [Indexed: 12/01/2022]
Abstract
Solvent-based protein precipitation provides exceptional recovery, particularly when the ionic strength of the solution is controlled. While precipitation is ideally suited for intact protein purification ahead of mass-spectrometry, low molecular weight (LMW) proteins and peptides are considered less susceptible to aggregation in organic solvent. As the combination of salt and organic solvent (i.e. acetone) has yet to be exploited to precipitate LMW proteins, we herein determine the low mass limit for solvent-based protein precipitation. We establish optimized conditions for high recovery precipitation of LMW proteins and peptides. Our results demonstrate a strong dependence on the type of salt to recover LMW components from complex mixtures. Inclusion of 100 mM ZnSO4 with 97% acetone provides near quantitative recovery of all peptides down to 2 kDa, and continues to exceed 90% yield for peptides at a molecular weight of 1 kDa. A detailed characterization of the precipitated peptides resulting from trypsin and pepsin digestion of complex systems is provided by bottom-up mass spectrometry.
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Affiliation(s)
- Venus Baghalabadi
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, Halifax, NS, B3H 4R2, Canada; Department of Chemistry, Faculty of Basic Sciences, Azarbaijan Shahid Madani University, P.O. Box 53714-161, Tabriz, Iran
| | - Alan A Doucette
- Department of Chemistry, Dalhousie University, 6274 Coburg Road, Halifax, NS, B3H 4R2, Canada.
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65
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Nielen WM, Willott JD, Esguerra ZM, de Vos WM. Ion specific effects on aqueous phase separation of responsive copolymers for sustainable membranes. J Colloid Interface Sci 2020; 576:186-194. [DOI: 10.1016/j.jcis.2020.04.125] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 01/09/2023]
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66
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Matsarskaia O, Roosen‐Runge F, Schreiber F. Multivalent ions and biomolecules: Attempting a comprehensive perspective. Chemphyschem 2020; 21:1742-1767. [PMID: 32406605 PMCID: PMC7496725 DOI: 10.1002/cphc.202000162] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 05/13/2020] [Indexed: 12/13/2022]
Abstract
Ions are ubiquitous in nature. They play a key role for many biological processes on the molecular scale, from molecular interactions, to mechanical properties, to folding, to self-organisation and assembly, to reaction equilibria, to signalling, to energy and material transport, to recognition etc. Going beyond monovalent ions to multivalent ions, the effects of the ions are frequently not only stronger (due to the obviously higher charge), but qualitatively different. A typical example is the process of binding of multivalent ions, such as Ca2+ , to a macromolecule and the consequences of this ion binding such as compaction, collapse, potential charge inversion and precipitation of the macromolecule. Here we review these effects and phenomena induced by multivalent ions for biological (macro)molecules, from the "atomistic/molecular" local picture of (potentially specific) interactions to the more global picture of phase behaviour including, e. g., crystallisation, phase separation, oligomerisation etc. Rather than attempting an encyclopedic list of systems, we rather aim for an embracing discussion using typical case studies. We try to cover predominantly three main classes: proteins, nucleic acids, and amphiphilic molecules including interface effects. We do not cover in detail, but make some comparisons to, ion channels, colloidal systems, and synthetic polymers. While there are obvious differences in the behaviour of, and the relevance of multivalent ions for, the three main classes of systems, we also point out analogies. Our attempt of a comprehensive discussion is guided by the idea that there are not only important differences and specific phenomena with regard to the effects of multivalent ions on the main systems, but also important similarities. We hope to bridge physico-chemical mechanisms, concepts of soft matter, and biological observations and connect the different communities further.
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Affiliation(s)
| | - Felix Roosen‐Runge
- Department of Biomedical Sciences and Biofilms-Research Center for Biointerfaces (BRCB), Faculty of Health and SocietyMalmö UniversitySweden
- Division of Physical ChemistryLund UniversitySweden
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67
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Kobayashi M. An analysis on electrophoretic mobility of hydrophobic polystyrene particles with low surface charge density: effect of hydrodynamic slip. Colloid Polym Sci 2020. [DOI: 10.1007/s00396-020-04716-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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68
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69
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dos Santos AP, Uematsu Y, Rathert A, Loche P, Netz RR. Consistent description of ion-specificity in bulk and at interfaces by solvent implicit simulations and mean-field theory. J Chem Phys 2020; 153:034103. [DOI: 10.1063/5.0016103] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Alexandre P. dos Santos
- Instituto de Física, Universidade Federal do Rio Grande do Sul, Caixa Postal 15051, 91501-970 Porto Alegre, RS, Brazil
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Yuki Uematsu
- Department of Physics, Kyushu University, 819-0395 Fukuoka, Japan
| | | | - Philip Loche
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Roland R. Netz
- Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
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70
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He H, Liu Z, Chen S, He X, Wang X, Wang X. Active Role of Water in the Hydration of Macromolecules with Ionic End Group for Hydrophobic Effect-Caused Assembly. Macromolecules 2020. [DOI: 10.1021/acs.macromol.0c00683] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Huiwen He
- College of Materials Science and Engineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou 310014, China
| | - Zhen Liu
- School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China
| | - Si Chen
- College of Materials Science and Engineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou 310014, China
| | - Xiaohua He
- School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China
| | - Xu Wang
- College of Materials Science and Engineering, Zhejiang University of Technology, 18 Chaowang Road, Hangzhou 310014, China
| | - Xiaosong Wang
- Waterloo Institute for Nanotechnology and Department of Chemistry, University of Waterloo, Waterloo, ON, N2L 3G1, Canada
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71
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Cruz-León S, Schwierz N. Hofmeister Series for Metal-Cation-RNA Interactions: The Interplay of Binding Affinity and Exchange Kinetics. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:5979-5989. [PMID: 32366101 PMCID: PMC7304902 DOI: 10.1021/acs.langmuir.0c00851] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A large variety of physicochemical properties involving RNA depends on the type of metal cation present in solution. In order to gain microscopic insight into the origin of these ion specific effects, we apply molecular dynamics simulations to describe the interactions of metal cations and RNA. For the three most common ion binding sites on RNA, we calculate the binding affinities and exchange rates of eight different mono- and divalent metal cations. Our results reveal that binding sites involving phosphate groups preferentially bind metal cations with high charge density (such as Mg2+) in inner-sphere conformations while binding sites involving N7 or O6 atoms preferentially bind cations with low charge density (such as K+). The binding affinity therefore follows a direct Hofmeister series at the backbone but is reversed at the nucleobases leading to a high selectivity of ion binding sites on RNA. In addition, the exchange rates for cation binding cover almost 5 orders of magnitude, leading to a vastly different time scale for the lifetimes of contact pairs. Taken together, the site-specific binding affinities and the specific lifetime of contact pairs provide the microscopic explanation of ion specific effects observed in a wide variety of macroscopic RNA properties. Finally, combining the results from atomistic simulations with extended Poisson-Boltzmann theory allows us to predict the distribution of metal cations around double-stranded RNA at finite concentrations and to reproduce the results of ion counting experiments with good accuracy.
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72
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Dahlström C, López Durán V, Keene S, Salleo A, Norgren M, Wågberg L. Ion conductivity through TEMPO-mediated oxidated and periodate oxidated cellulose membranes. Carbohydr Polym 2020; 233:115829. [DOI: 10.1016/j.carbpol.2020.115829] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 12/18/2019] [Accepted: 01/02/2020] [Indexed: 10/25/2022]
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73
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Vera RE, Salazar‐Rodríguez F, Marquez R, Forgiarini AM. How the Influence of Different Salts on Interfacial Properties of Surfactant–Oil–Water Systems at Optimum Formulation Matches the Hofmeister Series Ranking. J SURFACTANTS DETERG 2020. [DOI: 10.1002/jsde.12406] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Ramon E. Vera
- Laboratorio FIRPUniversidad de Los Andes Mérida Av Don Tulio Febres Cordero, Mérida 5101 Venezuela
| | | | - Ronald Marquez
- Laboratorio FIRPUniversidad de Los Andes Mérida Av Don Tulio Febres Cordero, Mérida 5101 Venezuela
| | - Ana M. Forgiarini
- Laboratorio FIRPUniversidad de Los Andes Mérida Av Don Tulio Febres Cordero, Mérida 5101 Venezuela
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74
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Tabisz Ł, Rozwadowski Z, Katrusiak A, Łęska B. Exploring ion-ion preferences through structure-property correlations: amino acid-derived, bis(guanidinium) disiloxane salts. Sci Rep 2020; 10:646. [PMID: 31959807 PMCID: PMC6971042 DOI: 10.1038/s41598-020-57539-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 12/30/2019] [Indexed: 11/09/2022] Open
Abstract
In a more synthetical approach to the study of ion-specific phenomena, four dipodal bis(guanidinium) siloxanes have been synthesized starting from glycine, β-alanine, γ-aminobutanoic acid, L-proline and 1,3-bis(3-aminopropyl)tetramethyldisiloxane. Together with their non-amide progenitor they were comparatively studied in regards to their interactions with nine different anions: sulphate, chromate, molybdate, benzoate, chloride, azide, nitrite, nitrate and thiocyanate. Their aqueous solubilities, form, 1H NMR and FT-IR spectra were examined while searching for anion-specific interactions falling in- or outside of the Hofmeister series. We show that although the "chao-" and "kosmotropic" ions affect the properties of solutions in a predictable way, more selective cation-anion pairing is responsible for phase separation and crystallinity. As a prominent example, crystal structure of one of the benzoate salts was successfully obtained and reveals a synergy of hydrophobic packing, ionic and hydrogen bonding. Immobilized but still flexible siloxane bridges give rise to crystals described by P 42/n space group and neatly segregated into hydro- and lipophilic sections.
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Affiliation(s)
- Łukasz Tabisz
- Faculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, Poznań, 61-614, Poland.
| | - Zbigniew Rozwadowski
- Faculty of Chemical Technology and Engineering, Department of Inorganic and Analytical Chemistry, West Pomeranian University of Technology, Piastów 42, Szczecin, 71-065, Poland
| | - Andrzej Katrusiak
- Faculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, Poznań, 61-614, Poland
| | - Bogusława Łęska
- Faculty of Chemistry, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 8, Poznań, 61-614, Poland
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75
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Apparent protein cloud point temperature determination using a low volume high-throughput cryogenic device in combination with automated imaging. Bioprocess Biosyst Eng 2019; 43:439-456. [PMID: 31754791 DOI: 10.1007/s00449-019-02239-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 10/21/2019] [Indexed: 12/17/2022]
Abstract
Short-term parameters correlating to long-term protein stability, such as the protein cloud point temperature (Tcloud), are of interest to improve efficiency during protein product development. Such efficiency is reached if short-term parameters are obtained in a low volume and high-throughput (HT) manner. This study presents a low volume HT detection method for (sub-zero) Tcloud determination of lysozyme, as such an experimental method is not available yet. The setup consists of a cryogenic device with an automated imaging system. Measurement reproducibility (median absolute deviation of 0.2 °C) and literature-based parameter validation (Pearson correlation coefficient of 0.996) were shown by a robustness and validation study. The subsequent case study demonstrated a partial correlation between the obtained apparent Tcloud parameter and long-term protein stability as a function of lysozyme concentration, ion type, ionic strength, and freeze/thaw stress. The presented experimental setup demonstrates its ability to advance short-term strategies for efficient protein formulation development.
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76
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Xu F, Yao Y, Alvarez PJ, Li Q, Fu H, Yin D, Zhu D, Qu X. Specific ion effects on the aggregation behavior of aquatic natural organic matter. J Colloid Interface Sci 2019; 556:734-742. [DOI: 10.1016/j.jcis.2019.09.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 08/30/2019] [Accepted: 09/01/2019] [Indexed: 01/29/2023]
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77
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Heydarifard S, Gao W, Fatehi P. Impact of Counter Ions of Cationic Monomers on the Production and Characteristics of Chitosan-Based Hydrogel. ACS OMEGA 2019; 4:15087-15096. [PMID: 31552352 PMCID: PMC6751722 DOI: 10.1021/acsomega.9b01953] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 08/16/2019] [Indexed: 06/10/2023]
Abstract
Chitosan-based hydrogel has received considerable interests because of its appealing properties and applications in many areas. The primary objective of this work was to produce novel cationic chitosan-based hydrogels via polymerizing chitosan with two cationic monomers of the same structure but with different counter ions [2-(methacryloyloxy)ethyl]trimethylammonium methyl sulfate (METMS) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC). Polymerization of chitosan with the cationic monomers performed under the conditions of 50 °C, 5 h, 7 pH, and 2/1 mol/mol monomer/chitosan led to chitosan-METMS and -METAC with the cationic charge densities of 3.22 and 2.88 mequiv/g, respectively. Elemental analysis, gel permeation chromatography, Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry analyses were used to confirm the impact of counter ions of cationic monomers (i.e., polarizability of monomers) on their polymerization performance and the characteristics of induced chitosan-based hydrogels. Also, the results of this work postulated that the counter ions associated with the monomers could dramatically impact the water uptake and swelling properties of the generated chitosan-based hydrogels as well as their performance in adsorbing an anionic dye from a simulated solution.
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78
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Kiyohara K, Kawai Y. Hydration of monovalent and divalent cations near a cathode surface. J Chem Phys 2019; 151:104704. [PMID: 31521095 DOI: 10.1063/1.5113738] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Hydration of monovalent (Li+, Na+, K+, and Cs+) and divalent (Mg2+, Ca2+, Sr2+, and Ba2+) cations on a cathode surface was studied by a classical molecular dynamics simulation. The potential of mean force (PMF) for each cation species was calculated as a function of the distance from the cathode surface, and the potential barriers for dehydrating the first and second hydration shells near the cathode surface were estimated. The positions of the minimum of the PMF closest to the cathode surface were found to be in the order Li+ < Na+ < Mg2+ < Ca2+ < Sr2+ < Ba2+ < K+ < Cs+. It was found that Li+, Mg2+, Ca2+, Sr2+, and Ba2+ ions are most likely doubly hydrated when they are adsorbed on the cathode surface without an applied voltage, whereas Na+, K+, and Cs+ ions are most likely singly hydrated at room temperature. On the other hand, when a voltage of 1 V was applied to the electrodes, all the cation species that we studied appeared most likely to be singly hydrated on the cathode surface. The depths of the potential well closest to the cathode surface under an applied voltage of 1 V were found to be in the order Ba2+ < Sr2+ < Ca2+ < Mg2+ for the divalent cations and Li+ < Na+ < K+ < Cs+ for the monovalent cations in the set of models that we used. These orders coincide with the Hofmeister series from the kosmotropic to the chaotropic.
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Affiliation(s)
- Kenji Kiyohara
- Inorganic Functional Materials Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka 563-8577, Japan
| | - Yusuke Kawai
- Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan
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79
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Abstract
Structural disorder is widespread in regulatory protein networks. Weak and transient interactions render disordered proteins particularly sensitive to fluctuations in solution conditions such as ion and crowder concentrations. How this sensitivity alters folding coupled binding reactions, however, has not been fully understood. Here, we demonstrate that salt jointly modulates polymer properties and binding affinities of 5 disordered proteins from a transcription factor network. A combination of single-molecule Förster resonance energy transfer experiments, polymer theory, and molecular simulations shows that all 5 proteins expand with increasing ionic strengths due to Debye-Hückel charge screening. Simultaneously, pairwise affinities between the proteins increase by an order of magnitude within physiological salt limits. A quantitative analysis shows that 50% of the affinity increase can be explained by changes in the disordered state. Disordered state properties therefore have a functional relevance even if these states are not directly involved in biological functions. Numerical solutions of coupled binding equilibria with our results show that networks of homologous disordered proteins can function surprisingly robustly in fluctuating cellular environments, despite the sensitivity of its individual proteins.
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80
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Affiliation(s)
- Harrison Laurent
- Department of Physics and Astronomy, University of Leeds, Leeds, UK
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, UK
| | - Alan Soper
- ISIS Facility, STFC Rutherford Appleton Laboratory, Didcot, UK
| | - Lorna Dougan
- Department of Physics and Astronomy, University of Leeds, Leeds, UK
- Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, UK
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81
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Govrin R, Obstbaum T, Sivan U. Common Source of Cryoprotection and Osmoprotection by Osmolytes. J Am Chem Soc 2019; 141:13311-13314. [DOI: 10.1021/jacs.9b06727] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Roy Govrin
- Department of Physics and the Russell Berrie Nanotechnology Institute, Technion − Israel Institute of Technology, Technion City, Haifa 3200003, Israel
| | - Tal Obstbaum
- Department of Physics and the Russell Berrie Nanotechnology Institute, Technion − Israel Institute of Technology, Technion City, Haifa 3200003, Israel
| | - Uri Sivan
- Department of Physics and the Russell Berrie Nanotechnology Institute, Technion − Israel Institute of Technology, Technion City, Haifa 3200003, Israel
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82
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Klijn ME, Hubbuch J. Redesigning food protein formulations with empirical phase diagrams: A case study on glycerol-poor and glycerol-free formulations. Food Res Int 2019; 125:108609. [PMID: 31554045 DOI: 10.1016/j.foodres.2019.108609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 05/19/2019] [Accepted: 08/06/2019] [Indexed: 10/26/2022]
Abstract
Redesigning existing food protein formulations is necessary in situations where food authorities propose dose adjustments or removal of currently employed additives. Redesigning formulations involves evaluating substitute additives to obtain similar long-term physical stability as the original formulation. Such formulation screening experiments benefit from comprehensive data visualization, understanding the effects of substitute additives on long-term physical stability, and identification of short-term optimization targets. This work employs empirical phase diagrams to reach these benefits by combining multidimensional long-term protein physical stability data with short-term empirical protein properties. A case study was performed where multidimensional protein phase diagrams (1152 formulations) allowed for identification of stabilizing effects as a result of pH, methionine, sugars, salt, and minimized glycerol content. Corresponding empirical protein property diagrams (144 formulations) resulted in the identification of normalized surface tension as a short-term empirical protein property to reach long-term physical stability presumably similar to the original product, namely via preferential hydration. Additionally, changes in pH and salt were identified as environmental optimization targets to reach stability via repulsive electrostatic forces. This case study shows the applicability of the empirical phase diagram method to rationally perform formulation redesign screenings, while simultaneously expanding knowledge on protein long-term physical stability.
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Affiliation(s)
- Marieke E Klijn
- Institute of Engineering in Life Sciences, Section IV: Biomolecular Separation Engineering, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany
| | - Jürgen Hubbuch
- Institute of Engineering in Life Sciences, Section IV: Biomolecular Separation Engineering, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany.
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83
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The Hofmeister series: Specific ion effects in aqueous polymer solutions. J Colloid Interface Sci 2019; 555:615-635. [PMID: 31408761 DOI: 10.1016/j.jcis.2019.07.067] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 07/23/2019] [Accepted: 07/24/2019] [Indexed: 12/21/2022]
Abstract
Specific ion effects in aqueous polymer solutions have been under active investigation over the past few decades. The current state-of-the-art research is primarily focused on the understanding of the mechanisms through which ions interact with macromolecules and affect their solution stability. Hence, we herein first present the current opinion on the sources of ion-specific effects and review the relevant studies. This includes a summary of the molecular mechanisms through which ions can interact with polymers, quantification of the affinity of ions for the polymer surface, a thermodynamic description of the effects of salts on polymer stability, as well as a discussion on the different forces that contribute to ion-polymer interplay. Finally, we also highlight future research issues that call for further scrutiny. These include fundamental questions on the mechanisms of ion-specific effects and their correlation with polymer properties as well as a discussion on the specific ion effects in more complex systems such as mixed electrolyte solutions.
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84
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Dourado AHB, Munhos RL, Silva NA, Colle VD, Carvalho GGA, Oliveira PV, Arenz M, Varela H, Córdoba de Torresi SI. Opportunities and Knowledge Gaps of SO2 Electrocatalytic Oxidation for H2 Electrochemical Generation. ACS Catal 2019. [DOI: 10.1021/acscatal.9b01336] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- André H. B. Dourado
- Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 05508-080 São Paulo, São Paulo, Brazil
| | - Renan L. Munhos
- Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 05508-080 São Paulo, São Paulo, Brazil
| | - Norberto A. Silva
- Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 05508-080 São Paulo, São Paulo, Brazil
| | - Vinícius Del Colle
- Departamento de Química, Universidade Federal de Alagoas−Campus Arapiraca, Av. Manoel Severino Barbosa, 57309-005 Arapiraca, Alagoas, Brazil
- Instituto de Química de São Carlos, Universidade de São Paulo, C.P. 780, CEP 13560-970, São Carlos, São Paulo, Brazil
| | - Gabriel G. A. Carvalho
- Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 05508-080 São Paulo, São Paulo, Brazil
| | - Pedro V. Oliveira
- Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 05508-080 São Paulo, São Paulo, Brazil
| | - Matthias Arenz
- Department of Chemistry and Biochemistry, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Hamilton Varela
- Instituto de Química de São Carlos, Universidade de São Paulo, C.P. 780, CEP 13560-970, São Carlos, São Paulo, Brazil
| | - Susana I. Córdoba de Torresi
- Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 05508-080 São Paulo, São Paulo, Brazil
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85
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Ziefuß AR, Barcikowski S, Rehbock C. Synergism between Specific Halide Anions and pH Effects during Nanosecond Laser Fragmentation of Ligand-Free Gold Nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:6630-6639. [PMID: 31025868 DOI: 10.1021/acs.langmuir.9b00418] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Gold nanoclusters (AuNCs) with diameters smaller than 3 nm are an emerging field of research because they possess interesting optical properties, such as photoluminescence. However, to date, it is still difficult to distinguish whether these properties originate from the cores of the nanoparticles or from the adsorbates on their surfaces. Hence, there is a high demand for ligand-free, ultra-small particles because they make it possible to study ligand and core effects separately. Pulsed laser fragmentation in liquids (LFL) is a convenient route for the synthesis of ligand-free AuNCs. The influence of physical parameters, such as melting and evaporation, on the LFL process is well understood both theoretically and experimentally. However, the impact of the chemical composition of the medium during LFL, which critically affects the particle formation process, has been less well examined. Therefore, in this work, we elucidate the extent to which the ionic strength, the pH value, and the nature of the halide anion that is present, that is, F-, Cl-, Br-, or I-, influence the particle size distribution of the LFL product and the mean yield of small particles (<3 nm) of the product. We showed that the yield of small particles can be enhanced by the synergism between pH and specific ion effects, which probably is attributable to the adsorption of specific anions. In addition, our findings indicated that anion-based stabilization depends critically on the type of anion. A direct Hofmeister effect was observed for anions in the neutral pH regime, whereas an indirect Hofmeister series was reported in alkaline solution, which probably was due to the more hydrophilic surfaces of the AuNCs that were formed.
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Affiliation(s)
- Anna Rosa Ziefuß
- University of Duisburg-Essen and Center for Nanointegration Duisburg-Essen (CENIDE) , Essen 45145 , Germany
| | - Stephan Barcikowski
- University of Duisburg-Essen and Center for Nanointegration Duisburg-Essen (CENIDE) , Essen 45145 , Germany
| | - Christoph Rehbock
- University of Duisburg-Essen and Center for Nanointegration Duisburg-Essen (CENIDE) , Essen 45145 , Germany
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86
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Sthoer A, Hladílková J, Lund M, Tyrode E. Molecular insight into carboxylic acid-alkali metal cations interactions: reversed affinities and ion-pair formation revealed by non-linear optics and simulations. Phys Chem Chem Phys 2019; 21:11329-11344. [PMID: 31107479 DOI: 10.1039/c9cp00398c] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Specific interactions between the carboxylic acid moiety and the monovalent salts CsCl, NaCl, and LiCl, have been investigated in Langmuir monolayers using vibrational sum frequency spectroscopy (VSFS) and complemented with coarse grained and all-atom molecular dynamics simulations. By exploiting VSFS's intrinsic surface specificity, an emphasis was made on targeting headgroup vibrations of both its charged and uncharged forms as well as water molecules in the interfacial layer. The degree of deprotonation of the monolayer as a function of cation concentration and pH was experimentally determined and theoretically rationalized. Starting from 100 mM, the surface charge was overestimated by the Gouy-Chapman model and varied depending on the identity of the cation, highlighting the appearance of ion specific effects. Agreement could be found using a modified Poisson-Boltzmann model that takes into account steric effects, with a fitted effective ion-size compatible with the hydrated ion diameters. The relative affinity of the cations to the carboxylic acid moiety was pH dependent: at pH 4.5 they arranged in the order Cs+ > Na+ > Li+, but fully reversed (Li+ > Na+ > Cs+) at pH 9. Simulations yielded microscopic insight into the origin of this behavior, with the cations showing contrasting interaction preferences for either the uncharged carboxylic acid or the charged carboxylate. Sum frequency spectra also provided evidence that all cations remained hydrated when interacting with the charged headgroup, forming solvent-separated or solvent-shared ion pairs. However, for the specific case of 1 M Li+ at pH 9, contact ion pairs were formed. Finally, the remarkable effect of trace metal multivalent cations in the interpretation of experiments is briefly discussed. The results provide exciting new insights into the complex interactions of alkali metal cations with the biophysically relevant carboxylic acid moiety.
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Affiliation(s)
- Adrien Sthoer
- Department of Chemistry, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden.
| | - Jana Hladílková
- Division of Theoretical Chemistry, Lund University, P.O.B. 124, SE-22100 Lund, Sweden
| | - Mikael Lund
- Division of Theoretical Chemistry, Lund University, P.O.B. 124, SE-22100 Lund, Sweden
| | - Eric Tyrode
- Department of Chemistry, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden.
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87
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van Lin S, Grotz KK, Siretanu I, Schwierz N, Mugele F. Ion-Specific and pH-Dependent Hydration of Mica-Electrolyte Interfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5737-5745. [PMID: 30974056 PMCID: PMC6495383 DOI: 10.1021/acs.langmuir.9b00520] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/05/2019] [Indexed: 05/05/2023]
Abstract
Hydration forces play a crucial role in a wide range of phenomena in physics, chemistry, and biology. Here, we study the hydration of mica surfaces in contact with various alkali chloride solutions over a wide range of concentrations and pH values. Using atomic force microscopy and molecular dynamics simulations, we demonstrate that hydration forces consist of a superposition of a monotonically decaying and an oscillatory part, each with a unique dependence on the specific type of cation. The monotonic hydration force gradually decreases in strength with decreasing bulk hydration energy, leading to a transition from an overall repulsive (Li+, Na+) to an attractive (Rb+, Cs+) force. The oscillatory part, in contrast, displays a binary character, being hardly affected by the presence of strongly hydrated cations (Li+, Na+), but it becomes completely suppressed in the presence of weakly hydrated cations (Rb+, Cs+), in agreement with a less pronounced water structure in simulations. For both aspects, K+ plays an intermediate role, and decreasing pH follows the trend of increasing Rb+ and Cs+ concentrations.
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Affiliation(s)
- Simone
R. van Lin
- Physics
of Complex Fluids Group and MESA+ Institute, Faculty of Science and
Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Kara K. Grotz
- Department
of Theoretical Biophysics, Max Planck Institute
of Biophysics, Max-von-Laue-Straße
3, 60438 Frankfurt
(Main), Germany
| | - Igor Siretanu
- Physics
of Complex Fluids Group and MESA+ Institute, Faculty of Science and
Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Nadine Schwierz
- Department
of Theoretical Biophysics, Max Planck Institute
of Biophysics, Max-von-Laue-Straße
3, 60438 Frankfurt
(Main), Germany
| | - Frieder Mugele
- Physics
of Complex Fluids Group and MESA+ Institute, Faculty of Science and
Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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88
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Brudar S, Hribar-Lee B. The Role of Buffers in Wild-Type HEWL Amyloid Fibril Formation Mechanism. Biomolecules 2019; 9:E65. [PMID: 30769878 PMCID: PMC6406783 DOI: 10.3390/biom9020065] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 02/04/2019] [Accepted: 02/05/2019] [Indexed: 01/06/2023] Open
Abstract
Amyloid fibrils, highly ordered protein aggregates, play an important role in the onset of several neurological disorders. Many studies have assessed amyloid fibril formation under specific solution conditions, but they all lack an important phenomena in biological solutions-buffer specific effects. We have focused on the formation of hen egg-white lysozyme (HEWL) fibrils in aqueous solutions of different buffers in both acidic and basic pH range. By means of UV-Vis spectroscopy, fluorescence measurements and CD spectroscopy, we have managed to show that fibrillization of HEWL is affected by buffer identity (glycine, TRIS, phosphate, KCl-HCl, cacodylate, HEPES, acetate), solution pH, sample incubation (agitated vs. static) and added excipients (NaCl and PEG). HEWL only forms amyloid fibrils at pH = 2.0 under agitated conditions in glycine and KCl-HCl buffers of high enough ionic strength. Phosphate buffer on the other hand stabilizes the HEWL molecules. Similar stabilization effect was achieved by addition of PEG12000 molecules to the solution.
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Affiliation(s)
- Sandi Brudar
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia.
| | - Barbara Hribar-Lee
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Večna pot 113, SI-1000 Ljubljana, Slovenia.
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89
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Ali N, Teixeira JA, Addali A, Saeed M, Al-Zubi F, Sedaghat A, Bahzad H. Deposition of Stainless Steel Thin Films: An Electron Beam Physical Vapour Deposition Approach. MATERIALS 2019; 12:ma12040571. [PMID: 30769827 PMCID: PMC6416557 DOI: 10.3390/ma12040571] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 02/03/2019] [Accepted: 02/04/2019] [Indexed: 02/07/2023]
Abstract
This study demonstrates an electron beam physical vapour deposition approach as an alternative stainless steel thin films fabrication method with controlled layer thickness and uniform particles distribution capability. The films were fabricated at a range of starting electron beam power percentages of 3–10%, and thickness of 50–150 nm. Surface topography and wettability analysis of the samples were investigated to observe the changes in surface microstructure and the contact angle behaviour of 20 °C to 60 °C deionised waters, of pH 4, pH 7, and pH 9, with the as-prepared surfaces. The results indicated that films fabricated at low controlled deposition rates provided uniform particles distribution and had the closest elemental percentages to stainless steel 316L and that increasing the deposition thickness caused the surface roughness to reduce by 38%. Surface wettability behaviour, in general, showed that the surface hydrophobic nature tends to weaken with the increase in temperature of the three examined fluids.
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Affiliation(s)
- Naser Ali
- Cranfield University, School of Aerospace, Transport and Manufacturing (SATM), MK430AL Cranfield, England, UK.
- Nanotechnology and Advanced Materials Program, Energy and Building Research Center, Kuwait Institute for Scientific Research, Safat 13109, Kuwait.
| | - Joao A Teixeira
- Cranfield University, School of Aerospace, Transport and Manufacturing (SATM), MK430AL Cranfield, England, UK.
| | - Abdulmajid Addali
- Cranfield University, School of Aerospace, Transport and Manufacturing (SATM), MK430AL Cranfield, England, UK.
| | - Maryam Saeed
- Nanotechnology and Advanced Materials Program, Energy and Building Research Center, Kuwait Institute for Scientific Research, Safat 13109, Kuwait.
| | - Feras Al-Zubi
- Nanotechnology and Advanced Materials Program, Energy and Building Research Center, Kuwait Institute for Scientific Research, Safat 13109, Kuwait.
| | - Ahmad Sedaghat
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran.
- Department of Mechanical Engineering, The Australian College of Kuwait, Safat 13015, Kuwait.
| | - Husain Bahzad
- Imperial College London, Department of Chemical Engineering, SW72AZ London, UK.
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90
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Effects of sort and concentration of salts on the electrosurface properties of aqueous suspensions containing hydrophobic and hydrophilic particles: Validity of the Hofmeister series. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2018.12.058] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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91
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Simonsson I, Sögaard C, Rambaran M, Abbas Z. The specific co-ion effect on gelling and surface charging of silica nanoparticles: Speculation or reality? Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2018.09.057] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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92
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Schwaab G, Sebastiani F, Havenith M. Untersuchung von Ionenhydratation und Ionenpaarbildung mittels THz‐Spektroskopie. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201805261] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Gerhard Schwaab
- Lehrstuhl für Physikalische Chemie IIRuhr-Universität Bochum 44780 Bochum Deutschland
| | - Federico Sebastiani
- Lehrstuhl für Physikalische Chemie IIRuhr-Universität Bochum 44780 Bochum Deutschland
| | - Martina Havenith
- Lehrstuhl für Physikalische Chemie IIRuhr-Universität Bochum 44780 Bochum Deutschland
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93
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Schwaab G, Sebastiani F, Havenith M. Ion Hydration and Ion Pairing as Probed by THz Spectroscopy. Angew Chem Int Ed Engl 2018; 58:3000-3013. [PMID: 30022575 DOI: 10.1002/anie.201805261] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 07/17/2018] [Indexed: 11/12/2022]
Abstract
Ion hydration is of pivotal importance for many fundamental processes. Various spectroscopic methods are used to study the retardation of the hydration bond dynamics in the vicinity of anions and cations. Here we introduce THz-FTIR spectroscopy as a powerful method to answer the open questions. We show through dissection of THz spectra that we can pinpoint characteristic absorption features that can be attributed to the rattling modes of strongly hydrating ions within their hydration cages as well as vibrationally induced charge fluctuations in the case of weakly hydrating ions. Further analysis yields information on anion-cation cooperativity, the size of the dynamic hydration shell, as well as the lifetimes of these collective ion-hydration water modes and their connecting thermal bath states. Our study provides evidence for a non-additive behavior, thus questioning the simplified Hofmeister model. THz spectroscopy enables ion pairing to be observed and quantified at a high salt concentration.
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Affiliation(s)
- Gerhard Schwaab
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Federico Sebastiani
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
| | - Martina Havenith
- Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, 44780, Bochum, Germany
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94
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Assaf KI, Nau WM. The Chaotropic Effect as an Assembly Motif in Chemistry. Angew Chem Int Ed Engl 2018; 57:13968-13981. [PMID: 29992706 PMCID: PMC6220808 DOI: 10.1002/anie.201804597] [Citation(s) in RCA: 199] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 07/01/2018] [Indexed: 11/26/2022]
Abstract
Following up on scattered reports on interactions of conventional chaotropic ions (for example, I- , SCN- , ClO4- ) with macrocyclic host molecules, biomolecules, and hydrophobic neutral surfaces in aqueous solution, the chaotropic effect has recently emerged as a generic driving force for supramolecular assembly, orthogonal to the hydrophobic effect. The chaotropic effect becomes most effective for very large ions that extend beyond the classical Hofmeister scale and that can be referred to as superchaotropic ions (for example, borate clusters and polyoxometalates). In this Minireview, we present a continuous scale of water-solute interactions that includes the solvation of kosmotropic, chaotropic, and hydrophobic solutes, as well as the creation of void space (cavitation). Recent examples for the association of chaotropic anions to hydrophobic synthetic and biological binding sites, lipid bilayers, and surfaces are discussed.
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Affiliation(s)
- Khaleel I. Assaf
- Department of Life Sciences and ChemistryJacobs University BremenCampus Ring 128759BremenGermany
| | - Werner M. Nau
- Department of Life Sciences and ChemistryJacobs University BremenCampus Ring 128759BremenGermany
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95
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Affiliation(s)
- Khaleel I. Assaf
- Department of Life Sciences and Chemistry; Jacobs University Bremen; Campus Ring 1 28759 Bremen Deutschland
| | - Werner M. Nau
- Department of Life Sciences and Chemistry; Jacobs University Bremen; Campus Ring 1 28759 Bremen Deutschland
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96
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Mazzini V, Craig VSJ. Volcano Plots Emerge from a Sea of Nonaqueous Solvents: The Law of Matching Water Affinities Extends to All Solvents. ACS CENTRAL SCIENCE 2018; 4:1056-1064. [PMID: 30159403 PMCID: PMC6107870 DOI: 10.1021/acscentsci.8b00348] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Indexed: 05/25/2023]
Abstract
The properties of all electrolyte solutions, whether the solvent is aqueous or nonaqueous, are strongly dependent on the nature of the ions in solution. The consequences of these specific-ion effects are significant and manifest from biochemistry to battery technology. The "law of matching water affinities" (LMWA) has proven to be a powerful concept for understanding and predicting specific-ion effects in a wide range of systems, including the stability of proteins and colloids, solubility, the behavior of lipids, surfactants, and polyelectrolytes, and catalysis in water and ionic liquids. It provides a framework for considering how the ions of an electrolyte interact in manifestations of ion specificity and therefore represents a considerable conceptual advance on the Hofmeister or lyotropic series in understanding specific-ion effects. Underpinning the development of the law of matching water affinities were efforts to interpret the so-called "volcano plots". Volcano plots exhibit a stark inverted "V" shape trend for a range of electrolyte dependent solution properties when plotted against the difference in solvation energies of the ions that constitute the electrolyte. Here we test the hypothesis that volcano plots are also manifest in nonaqueous solvents in order to investigate whether the LMWA can be extended to nonaqueous solvents. First we examine the standard solvation energies of electrolytes in nonaqueous solvents for evidence of volcano trends and then extend this to include the solubility and the activity/osmotic coefficients of electrolytes, in order to explore real electrolyte concentrations. We find that with respect to the solvent volcano trends are universal, which brings into question the role of solvent affinity in the manifestation of specific-ion effects. We also show that the volcano trends are maintained when the ionic radii are used in place of the absolute solvation energies as the abscissa, thus showing that ion sizes, rather than the solvent affinities, fundamentally determine the manifestation of ion specificity. This leads us to propose that specific-ion effects across all solvents including water can be understood by considering the relative sizes of the anion and cation, provided the ions are spherical or tetrahedral. This is an extension of the LMWA to all solvents in which the "water affinity" is replaced with the relative size of the anion and cation.
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97
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Effect of Ionic Compounds of Different Valences on the Stability of Titanium Oxide Colloids. COLLOIDS AND INTERFACES 2018. [DOI: 10.3390/colloids2030032] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Titanium oxide particles of various morphologies have been prepared for applications of scientific or industrial interest in recent decades. Besides development of novel synthetic routes and solid-state characterization of the obtained particles, colloidal stability of titanium oxide dispersions was the focus of numerous research groups due to the high importance of this topic in applications in heterogeneous systems. The influence of dissolved ionic compounds, including monovalent salts, multivalent ions and polyelectrolytes, on the charging and aggregation behaviour of titanium oxide materials of spherical and elongated structures will be discussed in the present review.
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98
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O'Neill SC, Kanthe AD, Weber JA, Tu RS. 'Reverse' Hofmeister effects on the sol-gel transition rates for an α-helical peptide-PEG bioconjugate. Phys Chem Chem Phys 2018; 20:20287-20295. [PMID: 30039819 PMCID: PMC6124666 DOI: 10.1039/c8cp03316a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
We examine the dynamics of the sol-gel transition for end-functionalized linear- and 4-arm-peptides bioconjugated to poly-ethylene glycol (PEG) in aqueous environments with increasingly chaotropic (Cl- < Br- < I-) anions. A 23-amino acid peptide sequence is rationally designed to self-assemble upon folding into the ordered α-helical conformation due to the hydrophobic effect. We use Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) to quantify the ensemble average reversible secondary structure transitions as a function of electrolyte concentration and specific ion effects along the Hofmeister series. Subsequently, microrheology is used to quantify the kinetics of the gelation process, as it relates to folding and specific ion interactions. Our key findings were non-intuitive. We observe the faster evolution of the gel transitions in systems with more chaotropic anions. For our peptides in aqueous solution, "water-structuring" ions yield faster assembly behavior with a viscoelastic exponent, n, closer to unity representing self-assemblies that are Rouse-like. In contrast, ions that are "water-breaking" resulted in smaller viscoelastic exponents where self-assembly dynamics result in a viscoelastic exponent that suggests polymer entanglements.
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Affiliation(s)
- Sean C O'Neill
- Department of Chemical Engineering, The City College of City University of New York, 140th Street and Convent Avenue, Steinman Hall T313, New York, New York 10031, USA.
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99
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Krishnan M. A simple model for electrical charge in globular macromolecules and linear polyelectrolytes in solution. J Chem Phys 2018; 146:205101. [PMID: 28571334 PMCID: PMC5443701 DOI: 10.1063/1.4983485] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We present a model for calculating the net and effective electrical charge of globular
macromolecules
and linear polyelectrolytes such as proteins and DNA, given the concentration of monovalent
salt and pH in solution. The calculation is based on a numerical solution of the
non-linear Poisson-Boltzmann equation using a finite element discretized continuum
approach. The model simultaneously addresses the phenomena of charge regulation and
renormalization,
both of which underpin the electrostatics of biomolecules in solution. We show that while charge
regulation addresses the true electrical charge of a molecule arising from the acid-base
equilibria of its ionizable groups, charge renormalization finds relevance in the context of a
molecule’s interaction with another charged entity. Writing this electrostatic
interaction
free energy in
terms of a local electrical potential, we obtain an “interaction charge” for the molecule
which we demonstrate agrees closely with the “effective charge” discussed in charge
renormalization
and counterion-condensation theories. The predictions of this model agree well with direct
high-precision measurements of effective electrical charge of polyelectrolytes such as
nucleic acids and disordered proteins in solution, without tunable parameters. Including the
effective interior dielectric
constant for compactly folded molecules as a tunable parameter, the
model captures measurements of effective charge as well as published trends of
pKa
shifts in globular proteins. Our results suggest a straightforward general framework to
model electrostatics in biomolecules in solution. In offering a platform that
directly links theory and experiment, these calculations could foster a systematic
understanding of the interrelationship between molecular 3D structure and conformation,
electrical charge and electrostatic
interactions in
solution. The model could find particular relevance in situations where molecular crystal
structures are not available or rapid, reliable predictions are desired.
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Affiliation(s)
- M Krishnan
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland and Department of Physics, University of Zurich, Winterthurerstrasse 190, CH 8057 Zurich, Switzerland
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100
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Schöttl S, Horinek D. Salt effects in surfactant-free microemulsions. J Chem Phys 2018; 148:222818. [DOI: 10.1063/1.5022883] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Sebastian Schöttl
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
| | - Dominik Horinek
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
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