Effective electrostatic interaction between columnar colloids: roles of solvent steric hindrance, polarity, and surface geometric characteristics

Zhou, Shiqi

doi:10.1080/00268976.2023.2216632

Cited by 5 publications

(3 citation statements)

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“…The stability of colloidal particles in aqueous suspensions is intrinsically connected with their surface charge density, which is controlled by the pH of the solution. Similarly, the activity of many biologically relevant proteins and polyelectrolytes is influenced by the solution’s pH and ionic strength. ,,− A quantitative understanding of charge regulation in such complex systems is therefore crucial for a wide range of industrial and medical applications.…”

Section: Introductionmentioning

confidence: 99%

On the Validity of Constant pH Simulations

Bakhshandeh,

Levin

2024

J. Chem. Theory Comput.

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Constant pH (cpH) simulations are now a standard tool for investigating charge regulation in coarse-grained models of polyelectrolytes and colloidal systems. Originally developed for studying solutions with implicit ions, extending this method to systems with explicit ions or solvents presents several challenges. Ensuring proper charge neutrality within the simulation cell requires performing titration moves in sync with the insertion or deletion of ions, a crucial aspect often overlooked in the literature. Contrary to the prevailing views, cpH simulations are inherently grand-canonical, meaning that the controlled pH is that of the reservoir. The presence of the Donnan potential between the implicit reservoir and the simulation cell introduces significant differences between titration curves calculated for open and closed systems; the pH of an isolated (closed) system is different from the pH of the reservoir for the same protonation state of the polyelectrolyte. To underscore this point, in this paper, we will compare the titration curves calculated using the usual cpH algorithm with those from the exact canonical simulation algorithm. In the latter case, titration moves adhere to the correct detailed balance condition, and pH is calculated using the recently introduced surface Widom insertion algorithm. Our findings reveal a very significant difference between the titration isotherms obtained using the standard cpH algorithm and the canonical titration algorithm, emphasizing the importance of using the correct simulation approach when studying charge regulation of polyelectrolytes, proteins, and colloidal particles.

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Section: Introductionmentioning

confidence: 99%

On the Validity of Constant pH Simulations

Bakhshandeh,

Levin

2024

J. Chem. Theory Comput.

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“…These interactions are particularly important in complexation, surfactant aggregation, coagulation, molecular recognition, the development of waterproof coatings, and the formation and stabilization of proteins, biological membranes, and micelles [18][19][20][21][22]. The EIP between charged colloids in ion fluids is referred to as the effective electrostatic potential (EEP) [23][24][25][26][27][28][29][30], which arises from the interplay of electrical forces in the presence of other ions in the surrounding solution and is influenced by several factors, including surface charge, double layer, ionic J. Stat. Mech.…”

Section: Introductionmentioning

confidence: 99%

Variability of entropy force and its coupling with electrostatic and steric hindrance interactions

Zhou

2024

J. Stat. Mech.

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We investigated the effective interaction potential (EIP) between charged surfaces in solvent comprised of dipole dimer molecules added with a certain amount of ionic liquid. Using classical density functional theory, the EIP is calculated and decoupled into entropic and energy terms. Unlike the traditional Asakura–Oosawa (AO) depletion model, the present entropic term can be positive or negative, depending on the entropy change associated with solvent molecule migration from bulk into slit pore. This is determined by pore congestion and disruption of the bulk dipole network. The energy term is determined by the free energy associated with hard-core repulsion and electrostatic interactions between surface charges, ion charges, and polarized charges carried by the dipole dimer molecules. The calculations in this article clearly demonstrate the variability of the entropy term, which contrasts sharply with the traditional AO depletion model, and the corrective effects of electrostatic and spatial hindrance interactions on the total EIP; we revealed several non-monotonic behaviors of the EIP and its entropic and energy terms concerning solvent bulk concentration and solvent molecule dipole moment; additionally, we demonstrated the promoting effect of dipolar solvent on the emergence of like-charge attraction, even in 1:1 electrolyte solutions. The microscopic origin of the aforementioned phenomena was analyzed to be due to the non-monotonic change of dipolar solvent adsorption with dipole moment under conditions of low solution dielectric constant. The present findings offer novel approaches and molecular-level guidance for regulating the EIP. This insight has implications for understanding fundamental processes in various fields, including biomolecule-ligand binding, activation energy barriers, ion tunneling transport, as well as the formation of hierarchical structures, such as mesophases, micro-, and nanostructures, and beyond.

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“…Similarly the activity of many biologically relevant proteins and polyelectrolytes is controlled by the solution's pH and ionic strength. 1–18 Quantitative understanding of charge regulation in such complex systems is, therefore, of paramount importance in a wide range of industrial and medical applications. For some simple colloidal systems with a regular distribution of surface active groups, one can use the Poisson–Boltzmann theory with the charge regulation boundary condition to study the particle protonation state.…”

Section: Introductionmentioning

confidence: 99%