scholarly journals Driving Forces for Oppositely Charged Polyion Association in Aqueous Solutions: Enthalpic, Entropic, but Not Electrostatic

2016 ◽  
Vol 138 (3) ◽  
pp. 980-990 ◽  
Author(s):  
Jingcheng Fu ◽  
Joseph B. Schlenoff
Keyword(s):  
Aqueous Solutions ◽  
Driving Forces ◽  
Oppositely Charged

scholarly journals Removal of Methylene Blue from Aqueous Solutions by Using Nance (Byrsonima crassifolia) Seeds and Peels as Natural Biosorbents

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Lorena Robles-Melchor ◽  
Maribel Cornejo-Mazón ◽  
Diana Maylet Hernández-Martínez ◽  
Gustavo F. Gutiérrez-López ◽  
Santiago García-Pinilla ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Driving Forces ◽  
Physical Adsorption ◽  
Point Of Zero Charge ◽  
Transfer Coefficients ◽  
Fractal Structures ◽  
Free Energy Of Adsorption ◽  
Freundlich Isotherms ◽  
Byrsonima Crassifolia

Contamination of effluents with chemicals is a serious problem that impacts human health. Methylene blue is a cationic dye found frequently in industrial and urban sewages. In this work, dried grinded seeds and peels of nance were used as biosorbents in aqueous solutions at pH 7 and 10 (simulating urban and textile effluents) finding that Langmuir and Freundlich isotherms adequately described the sorption. Adsorption efficiencies were larger than 98% in all cases and slightly lower at pH 7 due to the closeness with the point of zero charge (pzc) of seeds and peels of nance (5.96 and 3.42, respectively). In all cases, Langmuir adsorption was favorable (RLa < 1), and Gibbs free energy of adsorption was negative indicating spontaneity, and since these values were larger than −80 but lower than 0 kJ/mol, the MB removal process was mainly due to physical interactions, a characteristic of physical adsorption. No significant differences were found amongst bulk mass transfer coefficients for the adsorption of both sorbents, indicating that both bioadsorbents had the same hydrodynamic and driving forces as well as depicted similar MB-adsorbent affinities. Interaction of MB with adsorbents was corroborated by FTIR spectroscopy, and the sorption was evidenced by scanning electron microscopy and image analysis which indicated that both adsorbents had fractal structures.

Driving Forces for Adsorption of Polyols onto Zeolites from Aqueous Solutions

2010 ◽  
Vol 114 (5) ◽  
pp. 1939-1945 ◽  
Author(s):  
Elizabeth E. Mallon ◽  
Aditya Bhan ◽  
Michael Tsapatsis
Keyword(s):  
Aqueous Solutions ◽  
Driving Forces

scholarly journals Drug Delivery Systems: Study of Inclusion Complex Formation between Methylxanthines and Cyclodextrins and Their Thermodynamic and Transport Properties

Biomolecules ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 196 ◽  
Author(s):  
Cecília I. A. V. Santos ◽  
Ana C. F. Ribeiro ◽  
Miguel A. Esteso
Keyword(s):  
Aqueous Solutions ◽  
Inclusion Complexes ◽  
Molecular Mechanisms ◽  
Driving Forces ◽  
Drug Carrier ◽  
Partial Molar Volumes ◽  
Ternary Mixtures ◽  
Multicomponent Systems ◽  
Therapeutic Uses ◽  
Dispersion Technique

This paper presents an analysis of the molecular mechanisms involved in the formation of inclusion complexes together with some structural interpretation of drug–carrier molecule interactions in aqueous multicomponent systems comprising methylxanthines and cyclodextrins. The determination of apparent partial molar volumes ( φ V ) from experimental density measurements, both for binary and ternary aqueous solutions of cyclodextrins and methylxanthines, was performed at low concentration range to be consistent with their therapeutic uses in the drug-releasing field. The estimation of the equilibrium constant for inclusion complexes of 1:1 stoichiometry was done through the mathematical modelling of this apparent molar property. The examination of the volume changes offered information about the driving forces for the insertion of the xanthine into the cyclodextrin molecule. The analysis on the volumes of transfer, Δ φ V , c , and the viscosity B-coefficients of transfer, ΔB, for the xanthine from water to the different aqueous solutions of cyclodextrin allowed evaluating the possible interactions between aqueous solutes and/or solute–solvent interactions occurring in the solution. Mutual diffusion coefficients for binary, and ternary mixtures composed by xanthine, cyclodextrin, and water were measured with the Taylor dispersion technique. The behavior diffusion of these multicomponent systems and the coupled flows occurring in the solution were analyzed in order to understand the probable interactions between cyclodextrin–xanthine by estimating their association constants and leading to clearer insight of these systems structure. The measurements were performed at the standard (298.15 ± 0.01) K and physiological (310.15 ± 0.01) K temperatures.

scholarly journals Oscillatory structural forces between charged interfaces in solutions of oppositely charged polyelectrolytes

Soft Matter ◽  
2020 ◽  
Vol 16 (42) ◽  
pp. 9662-9668
Author(s):  
Katarzyna Kubiak ◽  
Plinio Maroni ◽  
Gregor Trefalt ◽  
Michal Borkovec
Keyword(s):  
Aqueous Solutions ◽  
Atomic Force Microscope ◽  
Silica Particles ◽  
Atomic Force ◽  
Structural Forces ◽  
Oppositely Charged ◽  
Cationic Polyelectrolytes

Forces between negatively charged micron-sized silica particles were measured in aqueous solutions of cationic polyelectrolytes with the atomic force microscope (AFM).

Formation of complexes in aqueous solutions of amphiphilic triblock polyelectrolytes of different topologies and an oppositely charged protein

Soft Matter ◽  
2018 ◽  
Vol 14 (15) ◽  
pp. 2860-2869
Author(s):  
Aristeidis Papagiannopoulos ◽  
Maria Karayianni ◽  
Stergios Pispas ◽  
Aurel Radulescu
Keyword(s):  
Aqueous Solutions ◽  
Oppositely Charged ◽  
Formation Of Complexes

The complexation of lysozyme with aggregates of two triblock amphiphilic polyelectrolytes of different molecular topologies is investigated by scattering techniques.

scholarly journals INVESTIGATION OF INTERACTION BETWEEN L-HISTIDINE AND HETEROCYCLIC SUBSTANCES IN AQUEOUS SOLUTIONS BY UV SPECTROSCOPY

2018 ◽  
Vol 61 (8) ◽  
pp. 10
Author(s):  
Valentin G. Badelin ◽  
Galina N. Tarasova ◽  
Elena Yu. Tyunina ◽  
Svetlana A. Bichkova
Keyword(s):  
Aqueous Solutions ◽  
Nicotinic Acid ◽  
Drug Transport ◽  
Driving Forces ◽  
Ph Value ◽  
Uv Spectroscopy ◽  
Spectral Characteristics ◽  
Equilibrium Mixture ◽  
Stable Complex ◽  
Target Cells

Drug – macromolecular interactions are an important phenomenon in multicomponents physiological media, such as blood, membranes, intra- and extracellular fluids, etc. The investigation of the mechanisms and driving forces for the molecular processes of the complexes formation, drug transport, and their delivery to target-cells is one of the priority tasks of chemistry, biology and pharmacology. It is imperative that one first investigate the properties of model compounds of macromolecules in an aqueous medium before beginning studies of the more complex systems. The features of their behavior essentially determine the biological activity of macromolecules. One of the well recognized approaches to the study of molecular interactions in fluids is the use of spectroscopic methods. As part of the longer term objective to investigate different aspects of interaction processes between model substances of protein and drug precursor, we report the results of spectroscopic investigation of aqueous solutions containing heterocyclic compounds – L-hystidine, nicotinic acid and uracil at fixed pH value. The electronic absorption spectrums of L-histidine were obtained for aqueous solutions with nicotinic acid and uracil at pH = 7.3 and T=296 K by UV spectroscopy. The spectral characteristics of the interaction between L-histidine and nicotinic acid or uracil were determined. The binding constants and the stoichiometry of the complexes were calculated on the basis of the saturation curves. The calculation of the equilibrium mixture of ionic forms of the studied amino acid as a function of the pH of the medium was carried out according to the computer program RRSU. The forms of reagents existence in an aqueous solution with pH = 7.3 have been determined. The specific features of the interactions of histidine with nicotinic acid and uracil were founded. It was shown that the interaction of histidine with uracil leads to the somewhat more stable complex formation than one with nicotinic acid.

Nanostructures of colloidal complexes formed in oppositely charged polyelectrolyte/surfactant dilute aqueous solutions

2007 ◽  
Vol 23 (3) ◽  
pp. 305-311 ◽  
Author(s):  
S. Trabelsi ◽  
S. Guillot ◽  
H. Ritacco ◽  
F. Boué ◽  
D. Langevin
Keyword(s):  
Aqueous Solutions ◽  
Dilute Aqueous Solutions ◽  
Oppositely Charged

Collapse Transitions of Proteins and the Interplay Among Backbone, Sidechain, and Solvent Interactions

2018 ◽  
Vol 47 (1) ◽  
pp. 19-39 ◽  
Author(s):  
Alex S. Holehouse ◽  
Rohit V. Pappu
Keyword(s):  
Aqueous Solutions ◽  
Driving Forces ◽  
Three Dimensional ◽  
Polymer Physics ◽  
Solvent Interactions ◽  
Intrinsically Disordered ◽  
The Past ◽  
Collapse Transitions

Proteins can collapse into compact globules or form expanded, solvent-accessible, coil-like conformations. Additionally, they can fold into well-defined three-dimensional structures or remain partially or entirely disordered. Recent discoveries have shown that the tendency for proteins to collapse or remain expanded is not intrinsically coupled to their ability to fold. These observations suggest that proteins do not have to form compact globules in aqueous solutions. They can be intrinsically disordered, collapsed, or expanded, and even form well-folded, elongated structures. This ability to decouple collapse from folding is determined by the sequence details of proteins. In this review, we highlight insights gleaned from studies over the past decade. Using a polymer physics framework, we explain how the interplay among sidechains, backbone units, and solvent determines the driving forces for collapsed versus expanded states in aqueous solvents.

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