Hydrophobic Polyelectrolytes

Olea, Andrés F.

doi:10.1002/9781118165850.ch7

Cited by 8 publications

(11 citation statements)

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“…Indeed, in previous studies it was found that at low pH the 1:1 SMA variant collapses into a globular conformation that contains hydrophobic domains while the polymer is still water soluble (23). Such hydrophobic domains may occur within one polymer chain, but they also may be formed as a consequence of intermolecular interactions, when the polymers are present in aggregates containing multiple polymer chains termed ''polymeric micelles'' (24,25), as will be discussed later. Because the conformational state of the polymers is likely to be important for their interaction with lipid membranes, it was investigated how polymer conformation may be affected by the styrene/maleic acid and pH.…”

Section: The Number Of Charges Per Unit Length Of Polymer Determines mentioning

confidence: 90%

“…Their formation is the result of intermolecular interactions driven by the balance in the hydrophobic effect and electrostatic repulsions (25). The existence of polymeric micelles can be detected by monitoring the maximum emission wavelength of NR as function of polymer concentration (18,26).…”

Section: The Presence Of Hydrophobic Domains Leads To the Formation Omentioning

confidence: 99%

“…At higher concentration, the hydrophobic domains of multiple polymers may cluster together to decrease the hydrophobic surface area that is in contact with water, thereby decreasing the polarity of the environment of NR shifting the maximum emission to~625 nm. The concentration at which a break point in the maximum emission wavelength is observed that is characteristic for the formation of polymeric micelles is, in the case of polymers, often referred to as the ''CAC'' (25), which is analogous to the critical micelle concentration in the case of detergents. The other three SMA variants do show a clear transition in emission maximum as a function of concentration, and all three were found to have a similar CAC value of 5.9 mg/mL.…”

Section: The Presence Of Hydrophobic Domains Leads To the Formation Omentioning

confidence: 99%

“…However, we should note that we cannot rule out that the collapsed conformation of SMA copolymers, in general, can actually be described by a single hydrophobic styrene-rich core that is stabilized by a hydrophilic maleic acid-rich outside, rather than by the presence of multiple hydrophobic domains. It is also possible that the polymers possess a combination of both, with the exact structure depending on many variables, such as polymer composition, ionization state, and type of solvent (25,28).…”

Section: The Sma 14:1 Variantmentioning

confidence: 99%

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Effect of Polymer Composition and pH on Membrane Solubilization by Styrene-Maleic Acid Copolymers

Scheidelaar

Koorengevel

Walree

et al. 2016

Biophysical Journal

129

170

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The styrene-maleic acid (SMA) copolymer is rapidly gaining attention as a tool in membrane research, due to its ability to directly solubilize lipid membranes into nanodisk particles without the requirement of conventional detergents. Although many variants of SMA are commercially available, so far only SMA variants with a 2:1 and 3:1 styreneto-maleic acid ratio have been used in lipid membrane studies. It is not known how SMA composition affects the solubilization behavior of SMA. Here, we systematically investigated the effect of varying the styrene/maleic acid on the properties of SMA in solution and on its interaction with membranes. Also the effect of pH was studied, because the proton concentration in the solution will affect the charge density and thereby may modulate the properties of the polymers. Using model membranes of 1,2-dimyristoyl-sn-glycero-3-phosphocholine lipids at pH > pH agg , we found that membrane solubilization is promoted by a low charge density and by a relatively high fraction of maleic acid units in the polymer. Furthermore, it was found that a collapsed conformation of the polymer is required to ensure efficient insertion into the lipid membrane and that efficient solubilization may be improved by a more homogenous distribution of the maleic acid monomer units along the polymer chain. Altogether, the results show large differences in behavior between the SMA variants tested in the various steps of solubilization. The main conclusion is that the variant with a 2:1 styrene-to-maleic acid ratio is the most efficient membrane solubilizer in a wide pH range.

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Section: The Number Of Charges Per Unit Length Of Polymer Determines mentioning

confidence: 90%

Section: The Presence Of Hydrophobic Domains Leads To the Formation Omentioning

confidence: 99%

Section: The Presence Of Hydrophobic Domains Leads To the Formation Omentioning

confidence: 99%

Section: The Sma 14:1 Variantmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Polymer Composition and pH on Membrane Solubilization by Styrene-Maleic Acid Copolymers

Scheidelaar

Koorengevel

Walree

et al. 2016

Biophysical Journal

129

170

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show abstract

“…While in the latter case the conformations are dictated by entropic, elastic-like interactions, the induced interactions in good (poor) solvent favor coillike (stretched) chain conformations 1,2, 13,14 . In a number of relevant applications in biology and material science, these interactions come from hydrophobic/hydrophilic groups attached at the polymer beads embedded in an aqueous environment [15][16][17][18][19] . Functional groups can be also a) Electronic mail: amin.bakhshandeh@ufrgs.br b) Electronic mail: maximiliano.segala@ufrgs.br c) Electronic mail: colla@ufop.edu.br present at the monomer surface, in which case the dissociation of these groups in a polar medium leads to charged polymer chains (polyelectrolytes), thus releasing their counterions into the solution [20][21][22] .…”

Section: Introductionmentioning

confidence: 99%

Equilibrium conformations and surface charge regulation of spherical polymer brushes in stretched regimes

Bakhshandeh,

Segala,

Colla

2021

Preprint

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In the present work, we study the equilibrium conformations of linear polyelectrolytes tethered onto a spherical, oppositely charged core in equilibrium with an ionic reservoir of fixed concentration. Particular focus is placed on the situation of stretched chains, where the monomer concentration is known to display an inverse square-law decay far away from the spherical surface, which is then further extrapolated all the way down to the grafting core. While the equilibrium distributions of mobile ions are computed in the framework of a classical Density Functional Theory (cDFT) that incorporates both their size and electrostatic correlations within the grafted polyelectrolyte, the equilibrium configuration of the latter is described by its averaged radius of gyration, which is taken as a variational parameter that guarantees mechanical equilibrium across the polymer-solvent interface. The averaged particle size is then analyzed over a wide range of polymerization degrees, ionic concentrations and functionality of the polymer backbones. Two distinct regimes can be identified: at high ionic strengths, swelling of the grafted polymers is dominated by ionic entropic contribution as well as polymer size effects, whereas at low ionic concentrations a balance between electrostatic and entropic effects is the main driven mechanism for particle stretching. Using Monte Carlo simulations, we then proceed to investigate the effects of charge regulation when the brush core is further decorated with active functional sites randomly distributed over its surface, which act as receptors onto which dissolved acidic ions can be adsorbed.

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Effect of Polymer Micelles on Antifungal Activity of Geranylorcinol Compounds against Botrytis cinerea

Taborga¹,

Díaz²,

Olea

et al. 2015

J. Agric. Food Chem.

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Herein, we explore the potential use of two micelle-forming block copolymers, i.e., Pluronic F-127 and poly(ethylene oxide)-b-poly(caprolactone), for application of fungicide agents. The polymer effect on the in vitro fungicide activity of a series of geranyl orcinol derivatives against Botrytis cinerea has been assessed. The results show that, for all test compounds, the incorporation into micelles, formed by Pluronic F-127, produces a great enhancement of the inhibitory effect on the growth of B. cinerea. For some compounds, at the lowest tested concentration (50 ppm), the percentage of inhibition increases significantly (from 0-10 to 80-90%) when the application is made using a polymer solution instead of an ethanol/water mixture. The synthesis and structural determination of a series of eight geranylphenols/diacetates, which were used as fungicide agents, are also discussed. These results suggest that polymer micelles are promising systems for application of crop-protecting agents.

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Hydrophobic Polyelectrolytes

Cited by 8 publications

References 100 publications

Effect of Polymer Composition and pH on Membrane Solubilization by Styrene-Maleic Acid Copolymers

Effect of Polymer Composition and pH on Membrane Solubilization by Styrene-Maleic Acid Copolymers

Equilibrium conformations and surface charge regulation of spherical polymer brushes in stretched regimes

Effect of Polymer Micelles on Antifungal Activity of Geranylorcinol Compounds against Botrytis cinerea

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