Instabilities of charged polyampholytes

Kantor, Yacov; Kardar, Mehran

doi:10.1103/physreve.51.1299

Cited by 168 publications

(203 citation statements)

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“…At the same time have appeared models for chain conformation and solution structure: whereas, in analogy with a chain in bad solvent [2,18] simple transition between extended chain and collapsed chain, isotropic or a cigar-shaped succession of blobs (Khokhlov,[19]), was first proposed, Kardar and Kantor [20,21] and Dobrynin, Obukov, Rubinstein [22][23][24] have applied the concept of Rayleigh instability [25] to charged polymers in poor solvent, leading to a pearl necklace chain conformation, in parallel with Solis-de la Cruz [26], Lyulin et al [27], and others [28]. The chain is now a succession of extended parts (strings) and compact collapsed parts (pearls); most of the chain segment mass is concentrated in the pearls, with included or condensed counterions.…”

Section: Introductionmentioning

confidence: 99%

Pearl-Necklace-Like Chain Conformation of Hydrophobic Polyelectrolyte: a SANS Study of Partially Sulfonated Polystyrene in Water

2007

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The form factor of partially sulfonated polystyrene PSSNa (degree of sulfonation f =1, 0.72, 0.64 and 0.36), at polymer concentration 0.17M and 0.34M, without or with added salt (0 M, 0.34M, & 0.68M), is measured by Small Angle Neutron Scattering using the Zero Average Contrast method. The total scattering function is also measured, allowing us to extract the distinct interchain function and an apparent structure factor. The main result is the behavior of the form factor which shows contributions of spherical entities as well as extended chain parts. This is striking for 0.64, while for f = 0.36 the sphere contribution is more dominant. The conformation does not depend on polymer concentration. When salt is added, the sphere sizes do not vary, but the contribution Spiteri et al. Form factor of partially sulfonated polystyrene 2 attributed to the stretched parts does vary very much like for fully sulfonated PSSNa. Discussion of the interchain contribution permits to establish the level of interpenetration: solutions are interpenetrated for f= 0.64, and at the limit for f=0.36. The theoretical pearl necklace model appears very suitable to modeling the results. Comparisons are made with analytical calculation and simulation data of pearl necklace. While the respective roles of Rayleigh transition, heterogeneous architecture, and strong hydrophobicity of non sulfonated PS monomers remain under discussion, the data give an accurate three dimensional image of the pearl necklace in solution.

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Section: Introductionmentioning

confidence: 99%

Pearl-Necklace-Like Chain Conformation of Hydrophobic Polyelectrolyte: a SANS Study of Partially Sulfonated Polystyrene in Water

2007

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“…More formally, it has been shown [10,11] using 1=T expansion of R g , that at high temperatures for Q greater (smaller) than Q c the R g increases (decreases) with decreasing T . Monte Carlo [12,13] and exact enumeration [14] studies conÿrm that such T -dependence of R g persists for all temperatures.…”

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confidence: 99%

“…Splitting a random sequence of charges into two equal parts will not split the total excess charge into half: on the contrary, the excess charges of two subchains can have either the same or opposite signs. Monte Carlo studies indicate [12,13] that low-T conÿgurations consist of few almost neutral globules connected by charged necks, or even of a single almost neutral globule with charged tails sticking out of it. It is not clear whether there is just one well-deÿned low-T conformation, or several conformations of very di erent shapes with similar energies [23].…”

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Necklace model of randomly charged polymers

Kantor¹,

Kardar²,

Ertaş³

1998

Physica A: Statistical Mechanics and its Applications

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Spatial conformations of randomly charged polymers (polyampholytes (PAs)) strongly depend on their total (excess) charge Q. For Q larger (smaller) that some critical value the PA is expanded (collapsed). The transition between the collapsed and the expanded states is reminiscent of the Rayley shape instability of a charged drop. The expanded states can be approximately described using the necklace model, as a chain of interconnected compact globules. Randomness of the charge sequence along the chain modiÿes the simple model creating wide distribution of sizes of the "beads" of the necklace. A simple mathematical model was proposed to describe the shape of the necklace. ? 1998 Elsevier Science B.V. All rights reserved. The importance of understanding proteins [1] has attracted much attention to the statistical mechanics of heterogeneous polymers. A particular type of heteropolymers built with a mixture of positively and negatively charged groups along their backbone are called polyampholytes (PAs). Proteins are biomolecules formed from amino-acids. Out of 20 natural amino-acids, three are positively charged (Lys, Arg, His) and two are negatively charged (Asp, Glu) [2]. A statistical study of the charge distribution along the sequences of biomolecules [3] indicates that from the point of view of electrostatic interactions the charge sequences in proteins are only weakly (anti-)correlated. Thus, the proteins can be approximately treated as randomly charged PAs. Experiments on PAs and polyamphilic gels [ 4 -8] reveal an extreme sensitivity of their geometric properties on their overall charge. We will show that the presence of long-range electrostatic interactions indeed causes a rather unique behavior in such polymers: the spatial conformations of a single PA with unscreened electrostatic interactions at a low temperature T strongly depend on its total (excess) charge Q. We will demonstrate that the geometry of the system can be qualitatively described using simple models. PACS

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“…[17][18][19][20] When the charge balanced PA were synthesized at very high concentration, the opposite charges form dynamic ionic bonds of intra-and inter-chains. The inter-chain ionic bonds serve as physical crosslinking to form hydrogels.…”

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Self‐Adjustable Adhesion of Polyampholyte Hydrogels

et al. 2015

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Biological surfaces are very complex in nature. They have wide distribution in molecular species; including positive and negative charges, polar and non-polar groups. [1] A material to show adhesion to such biological surfaces should have the capability of creating enough adhesive interacting sites with these species in wet environment. [2] Conventional hydrogels usually have poor adhesion to biological surfaces. [3] This is because the adhesion in wet environment is usually based on the Columbic interaction that strongly depends on the charge combinations. [3,4] Many of the biological surfaces and hydrogels have net negative surface charge [5] and they are repulsive in water. Developing adhesives that possess the ability of quick, strong, and reversible adhesion to hydrogels and biological tissues regardless their net charge identity will substantially promote the application of hydrogels in biomedical applications. Several research groups have tried to develop different adhesive hydrogels based on surface modification, [6] mechanical interlocking, [7] making composites, [8] supramolecular recognition, [9] and nano-particles. [10,11] But these approaches have limitations in practical applications, such as lengthy and complicated way of processing, lack of water resistivity and universality, inability in non-residual removal, etc. [12] The clue to develop adhesives working for hydrogels and biological tissues hides in nature.Bacteria cells, ubiquitous in environment, can attach with almost any surfaces including human tissues, regardless the diversity in the surface chemistry. The self-adjustable capability of the extracellular polymeric matrix (EPM) of bacteria cells has made this possible. [13,14] EPM can provide sufficient interacting sites for adsorption of species at interface in response to substrates mechanical and chemical properties through re-distribution of their charged groups. [15] Inspired from nature, we intend to find out a self-adjustable hydrogel adhesive for adhesion to hydrogels and tissues. A self-adjustable surface is such a surface which can offer its species for the formation of attractive interaction depending on substrate charges through dynamic reorganization process. A possible design for achieving such a self-adjustable 3 adhesive is a hydrogel composed of both positively and negatively charged monomers.Presence of both charges in the hydrogel is expected to create attractive interacting sites with any charged surfaces regardless of their charge identity to facilitate adsorption. But this seems to be tricky, because incorporation of both type charges in the same hydrogel sometime encounters strong self-ionic association, which will made it impossible for the formation of bonds with other species residing in different surfaces or in some cases imbalance in component inside hydrogel offers a strong net charge over the surface, [16] which will prevent their non-specific adhesion property. We can overcome this problem by choosing a neutral (charge balanced) polyampholyte (PA) hydrogel th...

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Instabilities of charged polyampholytes

Cited by 168 publications

References 47 publications

Pearl-Necklace-Like Chain Conformation of Hydrophobic Polyelectrolyte: a SANS Study of Partially Sulfonated Polystyrene in Water

Pearl-Necklace-Like Chain Conformation of Hydrophobic Polyelectrolyte: a SANS Study of Partially Sulfonated Polystyrene in Water

Necklace model of randomly charged polymers

Self‐Adjustable Adhesion of Polyampholyte Hydrogels

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