Universal size ratios of Gaussian polymers with complex architecture: radius of gyration vs hydrodynamic radius

Haydukivska, Khristine; Blavatska, V.; Paturej, Jarosław

doi:10.1038/s41598-020-70649-z

Cited by 30 publications

(28 citation statements)

References 40 publications

(68 reference statements)

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“…Experimental Results: Swelling Curves and Rg/R H . The ratio between gyration and hydrodynamic radii is a relevant quantity in polymer science, widely used as a shape index (34,35). These two lengths differently characterize the average polymer distribution inside the macromolecular volume.…”

Section: Resultsmentioning

confidence: 99%

Two-step deswelling in the Volume Phase Transition of thermoresponsive microgels

Monte

Truzzolillo

Camerin

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Thermoresponsive microgels are one of the most investigated types of soft colloids, thanks to their ability to undergo a Volume Phase Transition (VPT) close to ambient temperature. However, this fundamental phenomenon still lacks a detailed microscopic understanding, particularly regarding the presence and the role of charges in the deswelling process. This is particularly important for the widely used poly(N-isopropylacrylamide)–based microgels, where the constituent monomers are neutral but charged groups arise due to the initiator molecules used in the synthesis. Here, we address this point combining experiments with state-of-the-art simulations to show that the microgel collapse does not happen in a homogeneous fashion, but through a two-step mechanism, entirely attributable to electrostatic effects. The signature of this phenomenon is the emergence of a minimum in the ratio between gyration and hydrodynamic radii at the VPT. Thanks to simulations of microgels with different cross-linker concentrations, charge contents, and charge distributions, we provide evidence that peripheral charges arising from the synthesis are responsible for this behavior and we further build a universal master curve able to predict the two-step deswelling. Our results have direct relevance on fundamental soft condensed matter science and on applications where microgels are involved, ranging from materials to biomedical technologies.

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Section: Resultsmentioning

confidence: 99%

Two-step deswelling in the Volume Phase Transition of thermoresponsive microgels

Monte

Truzzolillo

Camerin

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…The Stokes‐Einstein equation [64–67] describes how the diffusion constant, D , of a fully solvated spherical particle in non‐turbulent flow depends on various properties of both the solvent and the diffusing particle:

true D = \frac{k_{B} T}{c π η R_{H}},

…”

Section: Resultsmentioning

confidence: 99%

Atomistic Simulations of Dopamine Diffusion Dynamics on a Pristine Graphene Surface**

et al. 2022

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Carbon microelectrodes enable in vivo detection of neurotransmitters, and new electrodes are being developed to optimize the carbon surface. However, the work is mainly empirical and there have not been corresponding theoretical studies using molecular-level simulations of the diffusion and orientation of neurotransmitters near these surfaces. Here, we employ molecular dynamics simulations to investigate in atomistic detail the surface diffusion of dopamine (DA), its oxidation product dopamine-o-quinone (DOQ), and their protonated forms on the pristine basal plane of flat graphene. All DA species rapidly adsorb to the surface and remain adsorbed for the full length of the equilibrium simulations, even without a holding potential or graphene surface defects. The diffusivities of the adsorbed and the fully solvated DA are similar, and all molecular diffusion on the surface is slower than that of an adatom of comparable molecular weight. The protonated species diffuse more slowly than their corresponding neutral forms, and the oxidized species diffuse more rapidly. The underlying hexagonal graphene structure has little influence over the molecular adsorbate's lateral position. The vertical placement of the amine group on dopamine is highly dependent upon its charge, and the protonated amine prefers to be above the surface near the solvating waters. Solvation has a large effect on surface diffusivities when diffusion is compared to that in a vacuum. These are the first results of molecular dynamics simulations of dopamine diffusion at the aqueous-graphene interface, and they show that dopamine diffuses quickly on graphene surfaces, even without an applied potential. These calculations provide a basis for future simulations to predict the behavior of neurotransmitter diffusion on advanced carbon materials electrodes.

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“…Moreover, the radius of gyration is a criterion of the compatibility and assembling of phospholipid molecules and an index of the formation of systems like vesicles, liposomes, and micelles. Since the radius of gyration is the distance from the axis of rotation, naturally the value of the radius of gyration index decrease by assembling of DOPC and DOPE phospholipids and formation of the liposomal model during the time 55 . At the beginning of the simulation run, DDOPC and DOPE phospholipids are randomly and heterogeneously dispersed in the water medium.…”

Section: Resultsmentioning

confidence: 99%

Design and simulation of the liposomal model by using a coarse-grained molecular dynamics approach towards drug delivery goals

Parchekani

Allahverdi

Taghdir

et al. 2022

Sci Rep

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The simulated liposome models provide events in molecular biological science and cellular biology. These models may help to understand the cell membrane mechanisms, biological cell interactions, and drug delivery systems. In addition, the liposomes model may resolve specific issues such as membrane transports, ion channels, drug penetration in the membrane, vesicle formation, membrane fusion, and membrane protein function mechanism. One of the approaches to investigate the lipid membranes and the mechanism of their formation is by molecular dynamics (MD) simulations. In this study, we used the coarse-grained MD simulation approach and designed a liposome model system. To simulate the liposome model, we used phospholipids that are present in the structure of natural cell membranes (1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE)). Simulation conditions such as temperature, ions, water, lipid concentration were performed based on experimental conditions. Our results showed a liposome model (ellipse vesicle structure) during the 2100 ns was formed. Moreover, the analysis confirmed that the stretched and ellipse structure is the best structure that could be formed. The eukaryotic and even the bacterial cells have elliptical and flexible structures. Usually, an elliptical structure is more stable than other assembled structures. The results indicated the assembly of the lipids is directed through short-range interactions (electrostatic interactions and, van der Waals interactions). Total energy (Van der Waals and electrostatic interaction energy) confirmed the designed elliptical liposome structure has suitable stability at the end of the simulation process. Our findings confirmed that phospholipids DOPC and DOPE have a good tendency to form bilayer membranes (liposomal structure) based on their geometric shapes and chemical-physical properties. Finally, we expected the simulated liposomal structure as a simple model to be useful in understanding the function and structure of biological cell membranes. Furthermore, it is useful to design optimal, suitable, and biocompatible liposomes as potential drug carriers.

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Universal size ratios of Gaussian polymers with complex architecture: radius of gyration vs hydrodynamic radius

Cited by 30 publications

References 40 publications

Two-step deswelling in the Volume Phase Transition of thermoresponsive microgels

Two-step deswelling in the Volume Phase Transition of thermoresponsive microgels

Atomistic Simulations of Dopamine Diffusion Dynamics on a Pristine Graphene Surface**

Design and simulation of the liposomal model by using a coarse-grained molecular dynamics approach towards drug delivery goals

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