Structural and dynamic heterogeneity in associative networks formed by artificially engineered protein polymers

Rao, Ameya; Olsen, Bradley D.

doi:10.1039/d3sm00150d

Cited by 6 publications

(5 citation statements)

References 72 publications

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“…Another related relaxation process is manifested in multivalent polymer chains, which interact through multiple sticky domains. Recent data involving relatively short such chains suggest a relaxation mode governed by the simultaneous detachment of all stickers carried by a polymer, implying an exponential dependence of the relaxation time on valence similar to ours ( 39 ). The resulting macroscopic relaxation dynamics is however essentially exponential, either because of the relatively small valences involved or because valence fluctuations affect flexible polymers differently than our rigid cross-linkers.…”

Section: Discussionsupporting

confidence: 80%

Valence can control the nonexponential viscoelastic relaxation of multivalent reversible gels

Le Roy,

Song,

Lundberg

et al. 2024

Sci. Adv.

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Gels made of telechelic polymers connected by reversible cross-linkers are a versatile design platform for biocompatible viscoelastic materials. Their linear response to a step strain displays a fast, near-exponential relaxation when using low-valence cross-linkers, while larger supramolecular cross-linkers bring about much slower dynamics involving a wide distribution of timescales whose physical origin is still debated. Here, we propose a model where the relaxation of polymer gels in the dilute regime originates from elementary events in which the bonds connecting two neighboring cross-linkers all disconnect. Larger cross-linkers allow for a greater average number of bonds connecting them but also generate more heterogeneity. We characterize the resulting distribution of relaxation timescales analytically and accurately reproduce stress relaxation measurements on metal-coordinated hydrogels with a variety of cross-linker sizes including ions, metal-organic cages, and nanoparticles. Our approach is simple enough to be extended to any cross-linker size and could thus be harnessed for the rational design of complex viscoelastic materials.

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Section: Discussionsupporting

confidence: 80%

Valence can control the nonexponential viscoelastic relaxation of multivalent reversible gels

Le Roy,

Song,

Lundberg

et al. 2024

Sci. Adv.

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“…The dynamic processes in networks of ionizable polymers drive their unique characteristics and enable their many current and potential applications in lightweight technologies ranging from clean energy generation and storage to biotechnology. − Their structure and dynamics in melts and solutions are governed by the coupling of two distinctive energy scales, van der Waals interactions and electrostatic forces, resulting in the coupling of responses on multiple length and time scales. Beyond ionizable polymeric networks, the coupling between processes that occur on distinctive length scales is a key to resolving the behavior of associative soft materials including networks, gels and nanoparticles-polymer hybrids as well as polymer-membrane complexes, all driven by dynamic constraints formed by physical association of chains. − …”

Section: Introductionmentioning

confidence: 99%

From Molecular Constraints to Macroscopic Dynamics in Associative Networks Formed by Ionizable Polymers: A Neutron Spin Echo and Molecular Dynamics Simulations Study

Kosgallana,

Wijesinghe,

Senanayake

et al. 2024

ACS Polym. Au

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The association of ionizable polymers strongly affects their motion in solutions, where the constraints arising from clustering of the ionizable groups alter the macroscopic dynamics. The interrelation between the motion on multiple length and time scales is fundamental to a broad range of complex fluids including physical networks, gels, and polymer−nanoparticle complexes where long-lived associations control their structure and dynamics. Using neutron spin echo and fully atomistic, multimillion atom molecular dynamics (MD) simulations carried out to times comparable to that of chain segmental motion, the current study resolves the dynamics of networks formed by suflonated polystryene solutions for sulfonation fractions 0 ≤ f ≤ 0.09 across time and length scales. The experimental dynamic structure factors were measured and compared with computational ones, calculated from MD simulations, and analyzed in terms of a sum of two exponential functions, providing two distinctive time scales. These time constants capture confined motion of the network and fast dynamics of the highly solvated segments. A unique relationship between the polymer dynamics and the size and distribution of the ionic clusters was established and correlated with the number of polymer chains that participate in each cluster. The correlation of dynamics in associative complex fluids across time and length scales, enabled by combining the understanding attained from reciprocal space through neutron spin echo and real space, through large scale MD studies, addresses a fundamental long-standing challenge that underline the behavior of soft materials and affect their potential uses.

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“…41 Notably, neutron spin echo spectroscopy is better suited for segmental dynamics, not motion above Rg length scales. 42 While segmental dynamics help form our understanding of these systems, we believe the relevant phenomena will rely on interchain correlations and therefore be better related to macroscopic transport properties. Determining these properties requires a carefully selected method with the appropriate resolution to probe the guiding phenomena in crowded systems.…”

Section: Introductionmentioning

confidence: 99%

Extreme Dependence of Dynamics on Concentration in Highly Crowded Polyelectrolyte Solutions

Landfield,

Kalamaris,

Wang

2024

Preprint

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Charge carrying species, such as polyelectrolytes, are vital to natural and synthetic processes that rely on their dynamic behavior. Here, we utilize single molecule methods to probe this dynamic behavior using polylysine as a model polyelectrolyte. Through single-particle tracking techniques, the diffusivity of individual polyelectrolyte chains and overall system viscosity are determined for concentrated polylysine solutions. These studies show experimental scaling dependences much stronger than theoretical predictions for both neutral polymers and polyelectrolytes and draw into question whether power law based scaling theories are appropriate to describe concentrated charged systems. Similar dependences are observed in concentrated solutions prepared at a variety of pH and counterion conditions. Hindered system dynamics are attributed to contributions from monomeric friction and the large effective excluded volume of polyelectrolyte chains leading to glassy dynamics. These forces restrict the movement of polymers through the sample and their effects are seen over a wide range of concentrations. The framework of the Vrentas Duda free volume theory is used to compare polyelectrolyte and neutral systems. Supported by this theory, when the mass associated with the counterions is excluded from the total polymer mass diffusive scaling across environmental conditions collapses onto a common trendline. Overall, these results are applicable to behavior in crowded biological systems, such as intracellular environments where the mobility of proteins is strongly inhibited.

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Structural and dynamic heterogeneity in associative networks formed by artificially engineered protein polymers

Abstract: This work investigates static gel structure and cooperative multi-chain motion in associative networks using a well-defined model system composed of artificial coiled-coil proteins.

Cited by 6 publications

References 72 publications

Valence can control the nonexponential viscoelastic relaxation of multivalent reversible gels

Valence can control the nonexponential viscoelastic relaxation of multivalent reversible gels

From Molecular Constraints to Macroscopic Dynamics in Associative Networks Formed by Ionizable Polymers: A Neutron Spin Echo and Molecular Dynamics Simulations Study

Extreme Dependence of Dynamics on Concentration in Highly Crowded Polyelectrolyte Solutions

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