Soft-mode of charged chiral fibrous viruses (fd)

Kang, Kyongok

doi:10.1039/c6sm00528d

Cited by 3 publications

(6 citation statements)

References 58 publications

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“…However, at lower ionic strengths below 1 mM salt, slower microscopic dynamics are dominant as a result of the perpendicular motions of charged DNA rods. This dramatic increase of microscopic relaxation time at the lowest ionic strength (of 0.032 mM salt) is also confirmed by the existing "soft-mode" of charged DNA virus rods, where the twist free energy contribution is coupled to the slower rotational diffusion of charged fd rods at the lowest ionic strength (of 0.032 mM salt) 17 .…”

Section: Salt-dependent Effective Interactions and Microscopic Relaxasupporting

confidence: 71%

“…Thus the reason for much slowing down behavior in microscopic dynamics is the forming of collective softmodes for low ionic strengths in the chiral-nematic phase, as confirmed by dynamic light scattering 17 . This then leads to the glass concentration, reached at a higher concentration, for the particularly low ionic strengths (of 0.16-0.8 mM salt).…”

Section: Charged Dna-virus Rod Suspensionsmentioning

confidence: 86%

“…These systems serve as colloidal model systems of charged rods, which allow to study their collective behavior and to develop (semi-empirical) theories for their orientational dynamics 28,29 , field-induced criticality 31 , and critical slowing down of dynamics near phase boundaries 27,31 . These studies go well beyond the classic Onsager theory for the isotropic-nematic transition, where the chiral nature of the molecular structure of the DNA viruses lead to a twist energy that in turn leads to the formation of a chiral-nematic phase as well as several hierarchical chiral-mesophases on increasing the virus concentration 17 .…”

Section: Charged Dna-virus Rod Suspensionsmentioning

confidence: 99%

“…A series of studies has been performed on bacteriophage DNA-viruses (fd), both in non-equilibrium 29 and equilibrium conditions 17,24,30 . These systems serve as colloidal model systems of charged rods, which allow to study their collective behavior and to develop (semi-empirical) theories for their orientational dynamics 28,29 , field-induced criticality 31 , and critical slowing down of dynamics near phase boundaries 27,31 .…”

Section: Charged Dna-virus Rod Suspensionsmentioning

confidence: 99%

“…Therefore, below PATH III, the twist effect at the low ionic strengths is further affected by the enhanced couplings of rotation and translation (in particular, in the perpendicular direction) for the collective motions above the I-N coexistence concentration. Such couplings can be further extended to achieve a minimum coherence length, from the N-star (N*) phase to the X-pattern via electrostatic repulsive forces or torques 17 .…”

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confidence: 99%

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Equilibrium phase diagram and thermal responses of charged DNA-virus rod-suspensions at low ionic strengths

Kang

2021

Sci Rep

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The collective behavior of DNA is important for exploring new types of bacteria in the means of detection, which is greatly interested in the understanding of interactions between DNAs in living systems. How they self-organize themselves is a physical common phenomenon for broad ranges of thermodynamic systems. In this work, the equilibrium phase diagrams of charged chiral rods (fd viruses) at low ionic strengths (below a few mM) are provided to demonstrate both replicas of (or self-organized) twist orders and replica symmetry breaking near high concentration glass-states. By varying the ionic strengths, it appears that a critical ionic strength is obtained below 1–2 mM salt, where the twist and freezing of nematic domains diverge. Also, the microscopic relaxation is revealed by the ionic strength-dependent effective Debye screening length. At a fixed low ionic strength, the local orientations of twist are shown by two different length scales of optical pitch, in the chiral-nematic N* phase and the helical domains $$H_{D}$$ H D , for low and high concentration, respectively. RSB occurs in several cases of crossing phase boundary lines in the equilibrium phase diagram of DNA-rod concentration and ionic strength, including long-time kinetic arrests in the presence of twist orders. The different pathways of PATH I, II and III are due to many-body effects of randomized orientations for charged fd rods undergoing long-range electrostatic interactions in bulk elastic medium. In addition, the thermal stability are shown for chiral pitches of the N* phase and the abnormal cooling process of a specific heat in a structural glass. Here, the concentration-driven twist-effects of charged DNA rods are explored using various experimental methods involving image-time correlation, microscopic dynamics in small angle dynamic light scattering, optical activity in second harmonic generation, and differential scanning calorimetry for the glass state.

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Section: Salt-dependent Effective Interactions and Microscopic Relaxasupporting

confidence: 71%

Section: Charged Dna-virus Rod Suspensionsmentioning

confidence: 86%

Section: Charged Dna-virus Rod Suspensionsmentioning

confidence: 99%

Section: Charged Dna-virus Rod Suspensionsmentioning

confidence: 99%

mentioning

confidence: 99%

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Equilibrium phase diagram and thermal responses of charged DNA-virus rod-suspensions at low ionic strengths

Kang

2021

Sci Rep

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Anisotropic Diffusion and Phase Behavior of Cellulose Nanocrystal Suspensions

et al. 2019

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In this paper, we use dynamic light scattering in polarized and depolarized modes to determine the translational and rotational diffusion coefficients of concentrated rodlike cellulose nanocrystals in aqueous suspension. Within the range of studied concentrations (1–5 wt %), the suspension starts a phase transition from an isotropic to an anisotropic state as shown by polarized light microscopy and viscosity measurements. Small-angle neutron scattering measurements also confirmed the start of cellulose nanocrystal alignment and a decreasing distance between the cellulose nanocrystals with increasing concentration. As expected, rotational and translational diffusion coefficients generally decreased with increasing concentration. However, the translational parallel diffusion coefficient was found to show a local maximum at the onset of the isotropic-to-nematic phase transition. This is attributed to the increased available space for rods to move along their longitudinal axis upon alignment. This increased parallel diffusion coefficient thus confirms the general idea that rodlike particles gain translational entropy upon alignment while paying the price for losing rotational degrees of freedom. Once the concentration increases further, diffusion becomes more hindered even in the aligned regions due to a reduction in the rod separation distance. This leads once again to a decrease in translational diffusion coefficients. Furthermore, the relaxation rate for fast mode translational diffusion (parallel to the long particle axis) exhibited two regimes of relaxation behavior at concentrations where significant alignment of the rods is measured. We attribute this unusual dispersive behavior to two length scales: one linked to the particle length (at large wavevector q) and the other to a twist fluctuation correlation length (at low wavevector q) along the cellulose nanocrystal rods that is of a larger length when compared to the actual length of rods and could be linked to the size of aligned domains.

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Response of shear in bulk orientations of charged DNA rods: Taylor- and gradient-banding

Kang

2021

J. Phys. Commun.

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Shear-induced instabilities leading to various kinds of inhomogeneous flow profiles play an important role in the processing of complex fluids, ranging from polymeric materials to various types of biological systems. In previously studied systems, either Taylor banding, or gradient banding, or fracture is observed. In the present work we study a system for which all instabilities occur in orientation textures (OTs), and where Taylor banding occurs simultaneously with gradient banding. The system here consists of crowded suspensions of long and thin DNA-based rods (at a low ionic strength of 0.16 mM salt), where the applied shear rate is systematically varied, for concentrations well below and above the glass-transition concentration (12.4 mg ml−1). To simultaneously measure the velocity profile along the gradient direction, in fracture and gradient banding, the optical cell is placed in a specially designed heterodyne light scattering set up, where the scattering volume can be scanned across the cell gap. The results confirm that Taylor bands and gradient banding occur in the concentration of DNA rods and applied shear-rates (35–80 s−1). Taylor bands clearly show the flow access in vorticity-direction, while the gradient banding is rearranged as thick rolling flows of OTs, at the middle shear-rate (50 s−1). The observations can be then useful to facilitate other biological complex fluids and the glass-forming liquids.

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Soft-mode of charged chiral fibrous viruses (fd)

Cited by 3 publications

References 58 publications

Equilibrium phase diagram and thermal responses of charged DNA-virus rod-suspensions at low ionic strengths

Equilibrium phase diagram and thermal responses of charged DNA-virus rod-suspensions at low ionic strengths

Anisotropic Diffusion and Phase Behavior of Cellulose Nanocrystal Suspensions

Response of shear in bulk orientations of charged DNA rods: Taylor- and gradient-banding

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