Polyelectrolyte complex coacervation

Spruijt E, Cohen Stuart MA, van der Gucht J (2013) Linear viscoelasticity of polyelectrolyte complex coacervates. Macromolecules 46 1633-1641. doi 10.1021/ma301730n... 

Without growth factors, a mixture of HA, methylated collagen, and terpolymer was used to coat porous PCL meshes by polyelectrolyte complex coacervation [111]. The coated scaffolds supported better cell seeding efficiency and distribution as well as led to an upregulation of osteogenic gene expression (alkaline phosphatase, osteocalcin, and bone sialoprotein I and II) by MSC in vitro [111]. 

Any pair of oppositely charged polyelectrolytes capable of forming a Hquid complex coacervate can be used to form microcapsules by complex... 

Keywords Bio artificial pancreas, biomaterials, complex coacervation, immunoisolation, microencapsulation, polyelectrolytes, water soluble polymers. 

The following guidelines can be utilized for the preparation of stable microcap-sular membranes from the complex coacervation of oppositely charged polyelectrolytes. 

Several other investigators have reported microencapsulation methods based upon polyelectrolyte complexes [289, 343]. For example, oppositely-charged polyelectrolytes (Amberlite IR120-P (cationic) and Amberlite IR-400 (anionic)) were recently used along with acacia and albumin to form complex coacervates for controlled release microcapsule formations [343]. Tsai and Levy [344,345] produced submicron microcapsules by interfacial crosslinking of aqueous polyethylene imine) and an organic solution of poly(2,6 dimethyl... 

There is evidence that random mixing of partially charge-neutralized hydrated polyelectrolyte complexes inside the coacervate phase imparts higher configurational entropy to these less stiff polyelectrolyte molecules as compared to those in the pre-coacervation phase (Kaibara et al.,... 

Overbeek, J.T.G., Voorn, M.J. (1957). Phase separation in polyelectrolyte solutions the theory of complex coacervation. Journal of Cellular and Comparative Physiology, 49,... 

Coacervation. If an oil phase is emulsified in a polymer water solution, and the polymer is precipitated (for example) by changing the pH, the polymer precipitate (coacervate) has a tendency to accumulate at the interface. This is the coacervation process called simple if one polymer is involved and complex if two polymers are involved. If the coacervation is obtained by dropping one polymer solution into a polymer solution of opposite charge, this is termed interfacial coacervation, or polyelectrolyte complex formation . 

Mixtures of oppositely charged polyelectrolytes dissolved in water can interact to form a variety of precipitates, gels, or phase-separated solutions. What is formed depends on the mixing conditions and the density of ionic charges carried by the polymer chains. Polyelectrolytes with high charge densities usually interact to form precipitates. As the charge density decreases, liquid-liquid phase separation, called complex coacervation, occurs. 

Complex coacervation is affected by pH, polyelectrolyte concentration, polyelectrolyte mixing ratio, and the neutral salt concentration. It normally occurs over a limited pH range and is suppressed by neutral salts. The optimum polyelectrolyte mixing ratio is that which neutralizes the ionic charges carried by the polyelectrolytes. The coacervation intensity is increased by dilution, which has led some researchers to suggest that complex coacervation is the mechanism by which various polymeric species are selectively isolated and concentrated in biological systems. 

Complex coacervation is a phenomenon by which an aqueous solution of oppositely charged polyelectrolytes separates into two distinct phases. The more dense phase is called the complex coacervate or coacervate. It is a relatively concentrated polyelectrolyte solution. The second phase, a relatively dilute polyelectrolyte solution, is called the equiibrium liquid. The difference in concentration of the coacervate and equilibrium liquid phases is determined by the intensity of the coacervation interaction. The more intense this interaction is, the greater the concentration difference. ... 

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. 

Investigation of the Structure of Polyelectrolyte-Based Complex Coacervates and the Effects of Electrolyte Order of Addition... 

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