Polyion complex

Ion exchange is actually a far more complicated process than the simple exchange of one cation for another or one anion for another, particularly for complex polyions such as proteins and oligonucleotides. Each ion of the stationary or mobile phase is surrounded by a cluster of counterions and water. When an ion in the mobile phase is transferred to the stationary phase, the cluster of counterions and water surrounding it is partially or completely displaced. A similar event occurs at the binding site of the stationary phase. Ions displaced from the stationary phase undergo the converse process. The... 

Ionic polymers contain counterions that neutralize the charges on the bound ions. The counterions maybe grouped into three types (1) univalent, (2) di- or trivalent and (c) polymeric. Polymers with polymeric counterions are often called polysalts, polyelectrolyte complexes, polyion complexes, simplexes, or coacervates. 

Further progress in the field of IPECs has been associated with involvement of more complex polyionic architectures, such as branched ionic (co)polymers (polyelectrolyte stars and cylindrical polyelectrolyte brushes) as well as self-assemblies of linear ionic diblock copolymers (polymeric micelles) (Fig. 6a-c), into interpolyelectrolyte complexation. Synthesis of well-defined polymeric architectures with nonlinear topology has become possible only recently due to considerable developments in living and controlled polymerizations. In this section, we briefly... 

The optimum conditions for polyion complex formation between chitosan and hyaluronate were identified fhe compression exerfed fo manufacture the implant had no role to play in the release kinetics [28,92]. Various authors published data confirming fhaf fhe combinafion of chifosan and hyaluronic acid is always suscepfible fo swelling, even in fhe presence of cross-hnking. 

The aim of this review is to demonstrate the potential of surface forces measurement as a novel means for investigating surfaces and complex soft systems by describing our recent studies, which include cluster formation of alcohol, polyion adsorption, and polyelectrolyte brushes. 

The stoichiometry of the recharged DNA/PLL/SPLL particles was studied using sucrose-gradient ultracentrifugation of fluorescently labeled polyion complexes in 25 mM HEPES buffer. Rhodamine-labeled DNA (Rh-DNA) and either fluorescein-labeled PLL (Fl-PLL) or SPLL (Fl-SPLL) were used to determine their relative amounts within DNA... 

Surini S, Akiyama H, Morishita M, Nagai T, Takayama K. Release phenomena of insulin from an implantable device composed of a polyion complex of chitosan and sodium hyaluronate. J Controlled Release 2003 90 291-301. 

The situation is more complex in the reactions found in AB cements because neutralization is accompanied by ion binding. Although a polyion chain extends as the number of ionized groups increases, the binding of... 

The apparent degree of dissociation, fi, varies in a complex way with 0 and depends on the value of Q (Figure 4.3). Apart from the case Q=, where p decreases with 6, P shows little variation with 0. It slowly decreases when Q = 2, and when Q = 2 or 4 it increases slightly to a plateau. Consequently, in practical cases, P is unaffected by increases in the charge on the polyion associated with ionization. This conclusion is supported by the results of Nagasawa Kagawa (1957). 

Tamura A, Oishi M, Nagasaki Y (2009) Enhanced cytoplasmic delivery of siRNA using a stabilized polyion complex based on PEGylated nanogels with a cross-linked polyamine structure. Biomacromolecules 10 1818-1827... 

Polymer complexes associated with two or more complementary polymers are widely used in potential applications in the form of particles, hydrogels, films, and membranes. In particular, a polyion complex (PIC) can be easily formed when oppositely charged polyelectrolytes are mixed in aqueous solution and interact via... 

Fig. 9 Stabilization of polyion complex nanoparticles composed of poly(amino acid)s using hydrophobic interactions...

Y. Sato, T. Sawaguchi, Hirata, Y., F. Mizutani, and S. Yabuki, Glucose xidse/polyion complex-bilayer membrane for elimination of electroactive interferents in amperometric glucose sensor. Anal. Chim. Acta 364, 173-179 (1998). 

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