CONTINUUM ELECTROSTATICS INVESTIGATION OF IONIC MICELLES USING ATOMISTIC MODELS

The key parameter related to the structure of the electric double layer of ionic surfactant micelles – electrostatic potential – is considered. A brief overview of experimental methods and theoretical models for estimating electrostatic potential- is given. The calculating method for the electrostatic potential based on a numerical solution of the Poisson-Boltzmann equation using an atomistic model of anionic surfactant micelle - is proposed. The parameters necessary for the construction of atomistic models - are obtained from molecular dynamic modeling. The electrostatic potentials for the micelles of sodium dodecyl sulfate and cetyltrimethylammonium bromide at different ionic strengths - were calculated by this method. The results are discussed in comparison with the values calculated in the simplified model, the Ohshima – Healy – White equation.

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The effect of undulations on the electrostatic potential in a polyelectrolyte system

Philosophical Transactions of the Royal Society of London Series A Physical and Engineering Sciences ◽

10.1098/rsta.1994.0089 ◽

1994 ◽

Vol 348 (1687) ◽

pp. 209-228 ◽

Cited By ~ 7

Keyword(s):

Boundary Condition ◽

Integral Equation ◽

Electrostatic Potential ◽

Perturbation Technique ◽

Cylindrical Symmetry ◽

Potential Applications ◽

Poisson Boltzmann ◽

Poisson Boltzmann Equation ◽

The Green Function ◽

Constant Charge

I consider the effect of macromolecular undulation on the electrostatic potential around a rod-like molecule. This effort is set to demonstrate the use of a particular perturbation technique through application to a geometrical system of general colloidal interest. The Poisson—Boltzmann equation together with a constant charge boundary condition on the well defined surface of an undulating cylinder is reformulated in integral equation form by use of Green’s theorem. A perturbation solution appropriate to the deformed boundary can be extracted when the Green function is approximated by that relevant to a reference, undeformed cylinder. Numerical results demonstrate that undulation causes significant deviations (increases) in electrochemical properties from expected behaviour, assuming rigid cylindrical symmetry. By considering the total free energy of the system it is found that electrostatics tend to diminish the extent of the undulations. The predicted deviations are briefly discussed in light of measured intermolecular electrostatic forces acting in a condensed phase of close-packed DNA. The perturbation technique has potential applications to mathematically similar problems occurring in hydrodynamics.

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The interaction of two charged spheres in the Poisson–Boltzmann equation

Canadian Journal of Chemistry ◽

10.1139/v81-277 ◽

1981 ◽

Vol 59 (13) ◽

pp. 1860-1864 ◽

Cited By ~ 20

Author(s):

Joseph E. Ledbetter ◽

Thomas L. Croxton ◽

Donald A. McQuarrie

Keyword(s):

Boltzmann Equation ◽

Charge Density ◽

Surface Charge ◽

Electrostatic Potential ◽

Surface Charge Density ◽

Ionic Solution ◽

Poisson Boltzmann ◽

Poisson Boltzmann Equation ◽

Good Agreement ◽

Charged Spheres

The Poisson–Boltzmann equation for two large charged spheres immersed in an ionic solution with either constant surface charge density or constant surface potential is solved numerically. The repulsion between the spheres is calculated from the electrostatic potential in the double layer surrounding the spheres. Good agreement between this numerically calculated force and the force computed using the Derjaguin formula for spheres with constant surface charge density is found at small separations of the spheres.

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Interactions of short chain phenylalkanoic acids within ionic surfactant micelles in aqueous media

Journal of the Serbian Chemical Society ◽

10.2298/jsc110121182n ◽

2012 ◽

Vol 77 (2) ◽

pp. 201-210 ◽

Cited By ~ 2

Author(s):

Kashif Naeem ◽

Syed Shah ◽

Bushra Naseem ◽

Syed Shah

Keyword(s):

Cetyltrimethylammonium Bromide ◽

Alkyl Chain ◽

Aqueous Media ◽

Sodium Dodecyl ◽

Standard Free Energy ◽

Bulk Water ◽

Uv Spectra ◽

Ionic Surfactant ◽

Standard Free Energy Change ◽

Surfactant Micelles

% SDS KR nema Solubilization and interactions of phenylalkanoic acids induced by cationic surfactant, cetyltrimethylammonium bromide (CTAB) and an anionic surfactant, sodium dodecyl sulfate (SDS) was investigated spectrophotometrically at 25.0?C. The UV spectra of the additives (acids) were measured with and without surfactant above and below critical micelle concentration (cmc) of the surfactant. The presence of alkyl chain in phenylalkanoic acids is responsible for hydrophobic interaction resulting in shift of the spectra towards longer wavelength (red shift). The value of partition coefficient (Kx) between the bulk water and surfactant micelles and in turn standard free energy change of solubilization (?Gp?) were also estimated by measuring the differential absorbance (?A) of the additives in micellar solutions.

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Analytical resolution of the Poisson–Boltzmann equation for a cylindrical polyion immersed in an electrolyte solution: using the optimal linearization method

Canadian Journal of Physics ◽

10.1139/cjp-2018-0303 ◽

2019 ◽

Vol 97 (6) ◽

pp. 656-661

Author(s):

Leila Djebbara ◽

Mohammed Habchi ◽

Abdalhak Boussaid

Keyword(s):

Boltzmann Equation ◽

Electrolyte Solution ◽

Electrostatic Potential ◽

Analytical Calculation ◽

Linearization Method ◽

General Potential ◽

Poisson Boltzmann ◽

Poisson Boltzmann Equation ◽

Analytical Resolution ◽

Potential Conditions

By using the optimal linearization method (OLM), the potential of the electrical double layer created by a highly charged cylindrical polyion immersed in an electrolyte reservoir, which is represented by the so-called Poisson–Boltzmann equation (PBE), has been solved analytically under general potential conditions. For this system, three regions must be considered. The first one is in the near-neighborhood of the polyion and it is deprived of coions because of the repulsion phenomenon between the polyion and the coions, as proposed by Fuoss et al. (Proc. Natl. Acad. Sci. 37, 579 (1951). doi: 10.1073/pnas.37.9.579 ). For the second region, where the potential is slightly lower, we propose an OLM for solving the PBE. In the last region, where the potential is sufficiently low, the approximation of Debye–Hückel is adopted. This method allowed us to overcome some shortcomings in the analytical calculation of the electrostatic potential created by a polyion in an electrolyte solution.

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ELECTROSTATICS STUDY OF A SINGLE-STRANDED DNA: A PROSPECTIVE FOR SINGLE MOLECULE SEQUENCING

Biophysical Reviews and Letters ◽

10.1142/s1793048013500100 ◽

2014 ◽

Vol 09 (01) ◽

pp. 105-114

Author(s):

MOHAMMAD J. I. A. SAUDE ◽

BASHIR I. MORSHED

Keyword(s):

Dna Sequencing ◽

Single Molecule ◽

Electrostatic Potential ◽

Molecular Electrostatic Potential ◽

Special Issue ◽

Single Stranded Dna ◽

Poisson Boltzmann ◽

Poisson Boltzmann Equation ◽

Dynamics Simulations ◽

Nucleotide Bases

Single molecule DNA sequencing requires new approaches to identify nucleotide bases. Using molecular dynamics simulations, we investigate the intrinsic electrostatics of single-stranded DNA by solving the nonlinear Poisson–Boltzmann equation. The results show variations of the molecular electrostatic potential (MEP) within 3 nm from the center of the sugar backbone, with suitably differentiable variations at 1.4 nm distance. MEP variations among four nucleotide bases are the most significant near ~ 33.7° and ~ 326.3° angular orientation, while the influences of the neighboring bases on MEPs become insignificant after the 3rd-nearest neighbors. This analysis shows potential for direct electronic sequencing of individual DNA molecules. [Formula: see text]Special Issue Comment: This paper about DNA sequencing based on molecular electrostatic potential maps of the DNA in the channel is related to the Special Issue articles about: measuring enzymes,32 and solving single molecules' trajectories with the RDF approach33 and with the QuB software.34

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Examining sharp restart in a Monte Carlo method for the linearized Poisson–Boltzmann equation

Monte Carlo Methods and Applications ◽

10.1515/mcma-2020-2069 ◽

2020 ◽

Vol 26 (3) ◽

pp. 223-244

Author(s):

W. John Thrasher ◽

Michael Mascagni

Keyword(s):

Monte Carlo ◽

Free Energy ◽

Monte Carlo Algorithm ◽

Significant Bias ◽

Poisson Boltzmann ◽

Electrostatic Free Energy ◽

Poisson Boltzmann Equation ◽

The Stability ◽

Potential Methods ◽

The Individual

AbstractIt has been shown that when using a Monte Carlo algorithm to estimate the electrostatic free energy of a biomolecule in a solution, individual random walks can become entrapped in the geometry. We examine a proposed solution, using a sharp restart during the Walk-on-Subdomains step, in more detail. We show that the point at which this solution introduces significant bias is related to properties intrinsic to the molecule being examined. We also examine two potential methods of generating a sharp restart point and show that they both cause no significant bias in the examined molecules and increase the stability of the run times of the individual walks.

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Inhibition of Escherichia coli O157:H7 and Salmonella enterica Isolates on Spinach Leaf Surfaces Using Eugenol-Loaded Surfactant Micelles

Foods ◽

10.3390/foods8110575 ◽

2019 ◽

Vol 8 (11) ◽

pp. 575

Author(s):

Songsirin Ruengvisesh ◽

Chris R. Kerth ◽

T. Matthew Taylor

Keyword(s):

Escherichia Coli ◽

Salmonella Enterica ◽

Limit Of Detection ◽

Sodium Dodecyl ◽

Microbial Pathogens ◽

Escherichia Coli O157 ◽

Human Pathogens ◽

Surfactant Micelles ◽

Leaf Surfaces ◽

Spinach Leaf

Spinach and other leafy green vegetables have been linked to foodborne disease outbreaks of Escherichia coli O157:H7 and Salmonella enterica around the globe. In this study, the antimicrobial activities of surfactant micelles formed from the anionic surfactant sodium dodecyl sulfate (SDS), SDS micelle-loaded eugenol (1.0% eugenol), 1.0% free eugenol, 200 ppm free chlorine, and sterile water were tested against the human pathogens E. coli O157:H7 and Salmonella Saintpaul, and naturally occurring microorganisms, on spinach leaf surfaces during storage at 5 °C over 10 days. Spinach samples were immersed in antimicrobial treatment solution for 2.0 min at 25 °C, after which treatment solutions were drained off and samples were either subjected to analysis or prepared for refrigerated storage. Whereas empty SDS micelles produced moderate reductions in counts of both pathogens (2.1–3.2 log10 CFU/cm2), free and micelle-entrapped eugenol treatments reduced pathogens by >5.0 log10 CFU/cm2 to below the limit of detection (<0.5 log10 CFU/cm2). Micelle-loaded eugenol produced the greatest numerical reductions in naturally contaminating aerobic bacteria, Enterobacteriaceae, and fungi, though these reductions did not differ statistically from reductions achieved by un-encapsulated eugenol and 200 ppm chlorine. Micelles-loaded eugenol could be used as a novel antimicrobial technology to decontaminate fresh spinach from microbial pathogens.

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