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Journal of Colloid and Interface Science Jan 2022The molecular surface properties of zwitterionic polymer coatings are central to their ultra-low fouling properties and effectiveness as steric stabilizers in...
The molecular surface properties of zwitterionic polymer coatings are central to their ultra-low fouling properties and effectiveness as steric stabilizers in concentrated salt solutions. Here, Surface Force Apparatus measurements quantified the molecular forces between end-grafted poly(sulfobetaine) methacrylate thin films and mica, as a function of the chain grafting density and ionic strength. These results demonstrate that, at the ionic strengths considered, end-grafted poly(sulfobetaine) films can be described by models for polymers in good solvent. Parameters determined from data fits to the Milner-Witten-Cates or Dolan and Edwards models for dense or dilute chains, respectively, varied with ionic strength, in ways that reflect poly(sulfobetaine) swelling and the increased excluded volume strength of chain segments. These force measurements provide new insight into how polymer coverage and salt cooperate to regulate repulsive poly(sulfobetaine) steric barriers. These findings have implications for the design of grafted poly(sulfobetaine) as colloidal stabilizers or nonfouling surface coatings.
Topics: Aluminum Silicates; Betaine; Methacrylates; Osmolar Concentration
PubMed: 34392027
DOI: 10.1016/j.jcis.2021.08.004 -
Water Science and Technology : a... Mar 2022In a wastewater treatment plant (WWTP), several sludge streams exist and the composition of their liquid phase varies with time and place. For evaluating the potential...
In a wastewater treatment plant (WWTP), several sludge streams exist and the composition of their liquid phase varies with time and place. For evaluating the potential for formation of precipitates and equilibria for weak acids/bases, the ionic strength and chemical composition need to be known. This information is often not available in literature, and even neglected in chemical model-based research. Based on a literature review, we proposed three ranges of concentration (low, typical and high) for the major constituents of the liquid phase of the different streams in a WWTP. The study also discusses the reasons for the concentration evolution, and the exceptional cases, to allow readers to consider the right range depending on their situation. The ionic strength of the different streams and the contribution of its constituents were calculated based on the ionic composition. The major contributors to the ionic strength for the wastewater-based streams (influent, effluent and mixed sludge) were Na, Cl, Mg and Ca, representing 50-70% of the ionic strength. For digestate, NH and HCO accounted for 65-75% of the ionic strength. Even though the ionic strength is recognized to impact several important wastewater treatment processes, its utilization in literature is not always adequate, which is discussed in this study.
Topics: Osmolar Concentration; Sewage; Waste Disposal, Fluid; Wastewater; Water Purification
PubMed: 35358079
DOI: 10.2166/wst.2022.057 -
ACS Chemical Biology Oct 2017Knowledge of the ionic strength in cells is required to understand the in vivo biochemistry of the charged biomacromolecules. Here, we present the first sensors to...
Knowledge of the ionic strength in cells is required to understand the in vivo biochemistry of the charged biomacromolecules. Here, we present the first sensors to determine the ionic strength in living cells, by designing protein probes based on Förster resonance energy transfer (FRET). These probes allow observation of spatiotemporal changes in the ionic strength on the single-cell level.
Topics: Biosensing Techniques; HEK293 Cells; Humans; Hydrogen-Ion Concentration; Macromolecular Substances; Osmolar Concentration
PubMed: 28853549
DOI: 10.1021/acschembio.7b00348 -
Biophysical Journal Apr 2021Eukaryotic cells exploit dynamic and compartmentalized ionic strength to impact a myriad of biological functions such as enzyme activities, protein-protein interactions,...
Eukaryotic cells exploit dynamic and compartmentalized ionic strength to impact a myriad of biological functions such as enzyme activities, protein-protein interactions, and catalytic functions. Herein, we investigated the fluorescence depolarization dynamics of recently developed ionic strength biosensors (mCerulean3-linker-mCitrine) in Hofmeister salt (KCl, NaCl, NaI, and NaSO) solutions. The mCerulean3-mCitrine acts as a Förster resonance energy transfer (FRET) pair, tethered together by two oppositely charged α-helices in the linker region. We developed a time-resolved fluorescence depolarization anisotropy approach for FRET analyses, in which the donor (mCerulean3) is excited by 425-nm laser pulses, followed by fluorescence depolarization analysis of the acceptor (mCitrine) in KE (lysine-glutamate), arginine-aspartate, and arginine-glutamate ionic strength sensors with variable amino acid sequences. Similar experiments were carried out on the cleaved sensors as well as an E6G2 construct, which has neutral α-helices in the linker region, as a control. Our results show distinct dynamics of the intact and cleaved sensors. Importantly, the FRET efficiency decreases and the donor-acceptor distance increases as the environmental ionic strength increases. Our chemical equilibrium analyses of the collapsed-to-stretched conformational state transition of KE reveal that the corresponding equilibrium constant and standard Gibbs free energy changes are ionic strength dependent. We also tested the existing theoretical models for FRET analyses using steady-state anisotropy, which reveal that the angle between the dipole moments of the donor and acceptor in the KE sensor are sensitive to the ionic strength. These results help establish the time-resolved depolarization dynamics of these genetically encoded donor-acceptor pairs as a quantitative means for FRET analysis, which complement traditional methods such as time-resolved fluorescence for future in vivo studies.
Topics: Anisotropy; Biosensing Techniques; Fluorescence Polarization; Fluorescence Resonance Energy Transfer; Osmolar Concentration
PubMed: 33582140
DOI: 10.1016/j.bpj.2021.01.035 -
Journal of Colloid and Interface Science Mar 2021Understanding microbial adhesion and retention is crucial for controlling many processes, including biofilm formation, antimicrobial therapy as well as cell sorting and...
Understanding microbial adhesion and retention is crucial for controlling many processes, including biofilm formation, antimicrobial therapy as well as cell sorting and cell detection platforms. Cell detachment is inextricably linked to cell adhesion and retention and plays an important part in the mechanisms involved in these processes. Physico-chemical and biological forces play a crucial role in microbial adhesion interactions and altering the medium ionic strength offers a potential means for modulating these interactions. Real-time studies on the effect of ionic strength on microbial adhesion are often limited to short-term bacterial adhesion. Therefore, there is a need, not only for long-term bacterial adhesion studies, but also for similar studies focusing on eukaryotic microbes, such as yeast. Hereby, we monitored, in real-time, S. cerevisiae adhesion on gold and silica as examples of surfaces with different surface charge properties to disclose long-term adhesion, retention and detachment as a function of ionic strength using quartz crystal microbalance with dissipation monitoring. Our results show that short- and long-term cell adhesion levels in terms of mass-loading increase with increasing ionic strength, while cells dispersed in a medium of higher ionic strength experience longer retention and detachment times. The positive correlation between the cell zeta potential and ionic strength suggests that zeta potential plays a role on cell retention and detachment. These trends are similar for measurements on silica and gold, with shorter retention and detachment times for silica due to strong short-range repulsions originating from a high electron-donicity. Furthermore, the results are comparable with measurements in standard yeast culture medium, implying that the overall effect of ionic strength applies for cells in nutrient-rich and nutrient-deficient media.
Topics: Bacterial Adhesion; Osmolar Concentration; Quartz Crystal Microbalance Techniques; Saccharomyces cerevisiae; Surface Properties
PubMed: 33127054
DOI: 10.1016/j.jcis.2020.10.038 -
Langmuir : the ACS Journal of Surfaces... Jul 2018Electrostatic interaction is a strong, dominant nonspecific interaction which was extensively studied in protein-nanoparticle (NP) interactions [ Lounis , F. M. ; J....
Electrostatic interaction is a strong, dominant nonspecific interaction which was extensively studied in protein-nanoparticle (NP) interactions [ Lounis , F. M. ; J. Phys. Chem. B 2017 , 121 , 2684 - 2694 ; Tavares , G. M. ; Langmuir 2015 , 31 , 12481 - 12488 ; Antonov , M. ; Biomacromolecules 2010 , 11 , 51 - 59 ], whereas the role of hydrophobic interaction arising from the abundant hydrophobic residues of globule proteins upon protein-NP binding between the proteins and charged nanoparticles has rarely been studied. In this work, a series of positively charged magnetic nanoparticles (MNPs) were prepared via atom transfer radical polymerization and surface hydrophobicity differentiation was achieved through postpolymerization quaternization by different halohydrocarbons. The ionic strength- and hydrophobicity-responsive binding of these MNPs toward β-lactoglobulin (BLG) was studied by both qualitative and quantitative methods including turbidimetric titration, dynamic light scattering, and isothermal titration calorimetry. Judged from the critical binding pH and binding constant for MNP-BLG complexation, the dependence of binding affinity on surface hydrophobicity exhibited an interesting shift with increasing ionic strength, which means that the MNPs with higher surface hydrophobicity exhibits weaker binding affinity at lower ionic strength but stronger affinity at higher ionic strength. This interesting observation could be attributed to the difference in ionic strength responsiveness for hydrophobic and electrostatic interactions. In this way, the well-tuned binding pattern could be achieved with optimized binding affinity by controlling the surface hydrophobicity of MNPs and ionic strength, thus endowing this system with great potential to fabricate separation and delivery system with high selectivity and efficiency.
Topics: Hydrogen-Ion Concentration; Hydrophobic and Hydrophilic Interactions; Nanoparticles; Osmolar Concentration; Protein Binding; Proteins; Static Electricity
PubMed: 29933693
DOI: 10.1021/acs.langmuir.8b00944 -
Electrophoresis Mar 2010We present a numerical and experimental study of the effects of ionic strength on electrophoretic focusing and separations. We review the development of ionic strength...
We present a numerical and experimental study of the effects of ionic strength on electrophoretic focusing and separations. We review the development of ionic strength models for electrophoretic mobility and chemical activity and highlight their differences in the context of electrophoretic separation and focusing simulations. We couple a fast numerical solver for electrophoretic transport with the Onsager-Fuoss model for actual ionic mobility and the extended Debye-Huckle theory for correction of ionic activity. Model predictions for fluorescein mobility as a function of ionic strength and pH compare well with data from CZE experiments. Simulation predictions of preconcentration factors in peak mode ITP also compare well with the published experimental data. We performed ITP experiments to study the effect of ionic strength on the simultaneous focusing and separation. Our comparisons of the latter data with simulation results at 10 and 250 mM ionic strength show the model is able to capture the observed qualitative differences in ITP analyte zone shape and order. Finally, we present simulations of CZE experiments where changes in the ionic strength result in significant change in selectivity and order of analyte peaks. Our simulations of ionic strength effects in capillary electrophoresis compare well with the published experimental data.
Topics: Algorithms; Computer Simulation; Electrolytes; Electrophoresis, Capillary; Fluorescent Dyes; Hydrogen-Ion Concentration; Isoelectric Focusing; Models, Chemical; Osmolar Concentration
PubMed: 20191554
DOI: 10.1002/elps.200900560 -
Critical Reviews in Food Science and... Oct 2017The qualitative characteristics of meat products are closely related to the functionality of muscle proteins. Myofibrillar proteins (MPs), comprising approximately 50%... (Review)
Review
The qualitative characteristics of meat products are closely related to the functionality of muscle proteins. Myofibrillar proteins (MPs), comprising approximately 50% of total muscle proteins, are generally considered to be insoluble in solutions of low ionic strength (< 0.2 M), requiring high concentrations of salt (> 0.3 M) for solubilization. These soluble proteins are the ones which determine many functional properties of meat products, including emulsification and thermal gelation. In order to increase the utilization of meat and meat products, many studies have investigated the solubilization of MPs in water or low ionic strength media and determining their functionality. However, there still remains a lack of systematic information on the functional properties of MPs solubilized in this manner. Hence, this review will explore some typical techniques that have been used. The main procedures used for their solubilization, the fundamental principles and their functionalities in water (low ionic strength medium) are comprehensively discussed. In addition, advantages and disadvantages of each technique are summarized. Finally, future considerations are presented to facilitate progress in this new area and to enable water soluble muscle MPs to be utilized as novel meat ingredients in the food industry.
Topics: Meat; Muscle Proteins; Osmolar Concentration; Solubility; Water
PubMed: 26647280
DOI: 10.1080/10408398.2015.1110111 -
Journal of Chromatography. A Nov 2021In this report, we put forward an experimental method to determine the ionic strength of an aqueous solution. To this end, we have developed a theory of ionic strength I...
In this report, we put forward an experimental method to determine the ionic strength of an aqueous solution. To this end, we have developed a theory of ionic strength I expressed in terms of the retention ratios in field-flow fractionation (FFF) as I=κ(1-R)/(1-R)-ε. Here R is a measured retention ratio using an FFF technique, for instance, sedimentation FFF (SdFFF), and R is the sterically-corrected standard retention ratio as given by the standard retention theory (SRT) for a latex particle system of diameter d. For a standard latex system with known d (or R) and I, we can construct a linear calibration of I against (1-R)/(1-R). Therefore, if we measure the retention ratio R of a carrier liquid of which ionic strength is of interest, then we will be able to estimate the ionic strength from the calibration curve thus built. In this paper, we have demonstrated the relation of Iwith respect to (1-R)/(1-R) for the polystyrene latex systems of which information on R, R, and I is available from Ref. [1].
Topics: Calibration; Fractionation, Field Flow; Osmolar Concentration; Particle Size; Water
PubMed: 34656839
DOI: 10.1016/j.chroma.2021.462591 -
Langmuir : the ACS Journal of Surfaces... Aug 2021Fibrinogen (Fg) self-assembly is sensitive to the physicochemical properties of an environment like pH and ionic strength. These parameters tune the direction and...
Fibrinogen (Fg) self-assembly is sensitive to the physicochemical properties of an environment like pH and ionic strength. These parameters tune the direction and strength of noncovalent physical driving forces determining protein intermolecular interactions. The attraction-repulsion balance in intermolecular interactions of the multidomain protein Fg at pH values 3.5, 7.4, and 9.5 and varying ionic strengths of the water medium has been analyzed by the complex diffusive approach, proposed by us previously. The concentration dependence of protein collective diffusion was analyzed within the phenomenological approach, based on the frictional formalism of nonequilibrium thermodynamics proposed by H. Vink. The analysis of protein diffusion data has shown the fundamental difference in the physical nature and direction of interaction forces between protein molecules at different conditions. The paired interaction potential of protein molecules was characterized in terms of second virial coefficients and Hamaker constants within the Deryaguin-Landau-Verwey-Overbeek theory and the "porous" colloid particle model. Our results indicated the maximum Hamaker constant and dominance of the van der Waals attraction between Fg molecules at pH 7.4. The increase in pH up to 9.5 results in the zero values of the second virial coefficient and Hamaker constant, corresponding to the full reciprocal compensation for electrostatic repulsion and van der Waals attraction. In the acidic medium (pH 3.5), the strong electrostatic repulsion substantially exceeds the van der Waals attraction. A high ionic strength is characterized by a significant decrease of all intermolecular interactions, which is expressed in almost zero values of virial coefficients and the Hamaker constant. Thus, it is experimentally shown that the physiological conditions of the Fg environment (pH 7.4 and slight ionic strength) provide a high probability for peak physical attraction between fibrinogen molecules, which is used in nature to facilitate blood clotting.
Topics: Fibrinogen; Hydrogen-Ion Concentration; Osmolar Concentration; Static Electricity; Thermodynamics
PubMed: 34403253
DOI: 10.1021/acs.langmuir.1c01803