Polyelectrolytes conformation

Nilsson KPR, Herland A, Hammarstrdm P, Inganas O (2005) Conjugated polyelectrolytes conformation-sensitive optical probes for detection of amyloid fibril formation. Biochemistry 44 3718-3724... 

The analysis described above is useful for modelling colligative properties but does not address polyelectrolyte conformations. Polyelectrolyte conformations in dilute solution have been calculated using the worm-like chain model [103,104], Here, the polymer conformation is characterized by a persistence length (a measure of the local chain stiffness) [96]. One consequence of the... 

The kind of counterions present may also affect polyelectrolyte conformation. At very high salt concentration, part of the ionized groups on the polymer will become neutralized (due to ion pair formation), causing a more compact conformation. This depends somewhat on the kind of... 

Polyelectrolyte Conformation. Up till here, we have considered two compartments separated by a semipermeable membrane. However, this is not essential to the existence of the Donnan effect. In Figure 6.9 (especially 6.9c) a polyelectrolyte molecule is depicted with a volume around it that contains an excess of counterions and that is depleted of coions. Actually, there is no sharp boundary surface involved, since the difference in concentration between counterions and coions gradually decreases with distance from the polyelectrolyte molecule. This is reflected in the gradual decrease in electric potential, as depicted in Figure 6.8. Since there are no... 

Reed, W.F. Light Scattering Results on Polyelectrolyte Conformations, Diffusion and Interparticle Interactions and Correlations, invited entry for ACS Symposium Series 548, Macroion Characterization. Schmitz, K. Ed., ACS, 1994, pp. 297-314. 

Fig. 20 Polyelectrolyte conformation as a function of the degree of dissociation (a). Simulation snapshots of the polymer with e = 1.3, for several degrees of ionization a = 0.06 (a), a = 0.20 (b), a = 0.25 (c), and a = 0.33 (d). Counterions not shown. For better visibility the snapshots differ in magnification the real sizes of the monomer units are the same in all cases...

Monte Carlo simulations provide a rewarding and invaluable approach to solving these systems, and computer simulations and theory can isolate the molecular factors that control polyelectrolyte conformations in solution. Therefore, they are exU cmely useful to address the optimization of colloid-polymer mixtures and guide the design of new experiments. A simple model involving one chain interacting with one particle has been described, but the same model can be extended to more concentrated systems, e.g. involving several chains (and/or colloidal particles) with explicit counter ions, co-ions and solvent molecules. 

Nilsson, K. P. R. Hammarstrom, P. Ahlgren, R Herland, A. Schnell, E. A. Lind-gren, M. Westermark, G. T. Inganas, O. Conjugated polyelectrolytes—conformation-sensitive optical probes for staining and characterization of amyloid deposits. Chem-BioChem 2006, 7,1096-1104. 

Sorci GA, Reed WF. Effect of ion type and valence on polyelectrolyte conformations and interactions. Macromolecules 2004 37 554-565. 

In all these studies, ACM allowed, with the massive data provided, the behavior of the polyelectrolyte conformational and interaction parameters to be followed at a level of detail previously unobtainable by manual gathering of individual data points. Correlations were made between experimental data and of electrostatic persistence length and electrostatic excluded volume theories, with no adjustable parameters. 

An investigation on the effect of added electrolyte valence and species on polyelectrolytes studied using ACM was made in Reference [46], First-order differences in polyelectrolyte conformations, interactions, and hydrodynamics were reported by the authors when electrolytes of different valence and symmetry were added to the polyelectrolyte solution. Each relevant characteristic, however, followed the same scaling relationship to ionic strength but the prefactors were different. Electrostatic persistence length/electrostatic excluded volume calculations without adjustable parameters suggested that the effective linear charge density is considerably lower in the presence of divalent ions than monovalent ions. Consideration of the... 

Bayly EE, Brousseau J-L, Reed WF. Continuous monitoring of the effect of changing solvent conditions on polyelectrolyte conformations and interactions. Int J Polym Anal Char 2002 7 1-18. 

Auramine O and ethidium bromide interactions with hypercoiling olefin maleic acid copolymers have been used as probes to study the polyelectrolyte conformations.The two cationic dyes responded in fluorescence or in visible spectra to changes in conformation of aqueous solutions of maleic acid copolymers with ethylene, isobutene, 2-methyl-l-pentene, or 2,4,4-trimethyl-1-pentene. The fraction of bound auramine is very sensitive to the presence of polyelectrolyte compact coils and to changes in ionic strength and type of counterions. The fluorescence spectra of the ethidium bromide systems also depended on the structure of the compact coils. Dye properties are correlated with the viscosity and equilibrium thermodynamic data for the various copolymers. 

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