A simple simulation model for complex coacervates

Bobbili, Sai Vineeth; Milner, Scott T.

doi:10.1039/d1sm00881a

Cited by 9 publications

(7 citation statements)

References 46 publications

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“…In our bead–spring model, all polymer beads and mobile counterions interact with repulsive Lennard-Jones interactions (eq ). Here ϵ = kT (2.49 kJ/mol at 300 K).…”

Section: Methodsmentioning

confidence: 99%

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Closed-Loop Phase Behavior of Nonstoichiometric Coacervates in Coarse-Grained Simulations

Bobbili

Milner

2022

Macromolecules

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Most studies of polyelectrolyte coacervate phase behavior focus on symmetric mixtures of oppositely charged polymers. Here we use a coarse-grained simulation, in which all bonded monomers and mobile counterions are represented as Lennard-Jones particles with unit charge and diameter equal to the Bjerrum length, to study the impact of charge asymmetry on coacervate phase behavior. We study the impact of salt on the concentration of polymers and mobile ions in each phase and qualitatively reproduce the closed-loop behavior observed in recent experiments on nonstoichiometric coacervates. We find that the counterions from added salt distribute unevenly, preferring the dilute phase to maximize their translational entropy, analogous to Donnan equilibrium for a charged membrane. The coacervate phase shrinks under osmotic pressure, leading to increased polymer concentration with small amounts of added salt.

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“…In our bead–spring model, all polymer beads and mobile counterions interact with repulsive Lennard-Jones interactions (eq ). Here ϵ = kT (2.49 kJ/mol at 300 K).…”

Section: Methodsmentioning

confidence: 99%

“…In our previous work, 43 we introduced a simple simulation model to obtain coacervate phase diagrams. In our bead− spring model, all ions on polymers, dissociated counterions, and ions from the added salt are represented by beads of unit charge and diameter equal to the Bjerrum length.…”

Section: ■ Introductionmentioning

confidence: 99%

Closed-Loop Phase Behavior of Nonstoichiometric Coacervates in Coarse-Grained Simulations

Bobbili

Milner

2022

Macromolecules

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“…Polyelectrolyte complex coacervates formed via an associative liquid–liquid phase separation by mixing oppositely charged polyelectrolyte (PE) solutions have a broad range of industrial applications, such as polymer film fabrication, hydrogel formation, and protein encapsulation. − In protein therapeutics, for example, protein drugs can be encapsulated in the polypeptide complex coacervate droplets for effective and efficient drug delivery and subsequent release. ,, Polyelectrolyte complex coacervates also have significant biological relevance due to their role in bioinspired adhesives, membraneless organelles, and artificial protocells. ,− In recent years, considerable efforts have been devoted to understanding the structure and dynamics of polyelectrolyte complex coacervates, and significant progress has been made on both the theoretical and experimental fronts; − we refer the reader...…”

Section: Introductionmentioning

confidence: 99%

Supernatant Phase in Polyelectrolyte Complex Coacervation: Cluster Formation, Binodal, and Nucleation

Zhang

Wang

2022

Macromolecules

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This work studies the structure and thermodynamics of the supernatant phase in polyelectrolyte complex coacervation, a relatively unexplored area. By combining the cluster theory in dilute solution with our recently developed mean-field theory for inhomogeneous polyelectrolyte solutions (ZhangP.WangZ.-G. Zhang, P. Wang, Z.-G. Macromolecules20215410994), we systematically investigate the structure of finite-sized clusters formed by oppositely charged polyions in symmetric dilute solutions and how these clusters affect the binodal, spinodal, and nucleation for polyelectrolyte complex coacervation. We find that both the polyion concentration deep inside the cluster and the interfacial tension decrease with increasing the cluster size, reaching their respective bulk coexistence values with corrections inversely proportional to the cluster radius. The polyion concentration in the supernatant phase at coexistence is several orders of magnitude higher than that obtained under the uniform mixing approximation. For most relevant conditions away from the critical point, the supernatant phase consists predominantly of polyion pairs. By examining the nucleation barrier in supersaturated solutions, we can determine a pseudo-spinodal when the barrier is a few multiples of the thermal energy. The location of this pseudo-spinodal is similarly shifted to much higher concentrations than predicted under the uniform mixing approximation. Making the volume approximation for the clusters, we obtain simple analytical expressions for the cluster formation free energy, the modified binodal, and the pseudo-spinodal. In particular, we propose a simple approximate formula for estimating the concentration of the coexisting supernatant phase in terms of the chain length, interfacial tension, and the polyion concentration in the coacervate phase.

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“…[240] Aside from experimental exploration, polymer theory and molecular dynamics simulations are also essential in understanding the properties of functional coacervate systems. [241][242][243]…”

Section: Discussionmentioning

confidence: 99%

Bio‐inspired functional coacervates

Chen

Guo

2022

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Many functional coacervates have been identified in biological systems, which have attracted widespread interest. Coacervation is a liquid-liquid phase separation (LLPS) process in which a macromolecule-enriched liquid phase is formed together with a macromolecule-depleted phase. Bio-inspired coacervates possess excellent features such as underwater delivery, low interface energy, shear thinning, and excellent biocompatibility. They also serve as good delivery platforms for different types of molecules. In this review, we briefly discuss some important extracellular coacervate systems, including mussel adhesives, sandcastle worm glue, squid beak, and tropoelastin. We then provide an overview of the recent development of bio-inspired functional coacervates for various biomedical applications, including medical adhesives, drug delivery, and tissue engineering. Bio-inspired functional coacervates offer a promising material platform for developing new materials for biomedical applications.

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A simple simulation model for complex coacervates

Abstract: When oppositely charged polyelectrolytes mix in an aqueous solution, associative phase separation gives rise to coacervates. Experiments reveal the phase diagram for such coacervates, and determine the impact of charge...

Cited by 9 publications

References 46 publications

Closed-Loop Phase Behavior of Nonstoichiometric Coacervates in Coarse-Grained Simulations

Closed-Loop Phase Behavior of Nonstoichiometric Coacervates in Coarse-Grained Simulations

Supernatant Phase in Polyelectrolyte Complex Coacervation: Cluster Formation, Binodal, and Nucleation

Bio‐inspired functional coacervates

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