Polyelectrolytes, natural

Note 3 Polyelectrolytes can be either synthetic or natural. Nucleic acids, proteins, teichoic acids, some polypeptides, and some polysaccharides are examples of natural polyelectrolytes. 

Schmitt-Kopplin, P., Garmash, A. V., Kudryavtsev, A. V., Perminova, I. V., Hertkorn, N., Freitag, D., and Kettrup, A. (1999b). Mobility distribution description of synthetic and natural polyelectrolytes with capillary zone electrophoresis. /. AOAC Int. 82,1594-1603. 

Some polypeptide helices and other natural polyelectrolytes... 

The above discussion dealt primarily with synthetic polyelectrolytes, which behave in solution more or less as flexible polymers. Another important group, the natural polyelectrolytes, will not be discussed here. They include polynucleic acids, proteins, carbohydrate derivates, etc. They generally behave as rigid-chain polymers, due to their helix conformation. 

Interactions between chemically and structurally complementary macromolecules have usually a cooperative character. Probably, the formation of cooperative systems involving two (or more) types of bonds at the same time (e.g. of ionic and hydrogen bonds)63 is possible. It should be mentioned here that hydrophobic interactions play an important role in the stabilization of synthetic and natural polyelectrolyte complexes and also of complexes with hydrogen bonds. The contribution of either interactions may be different, depending on the chemical structure of the components of the polycomplex and the nature of the medium. 

Mynin, V.N. and Terpugov, G.V., Purification of waste water from heavy metals by using ceramic membranes and natural polyelectrolytes, Desalination, 119, 361, 1998. 

Hydrocolloid-forming polysaccharides are natural polyelectrolytes able to gelify water when added in tiny amounts. Hydrogels containing 1-2% polymer and... 

Aggregation and fragmentation of colloidal particles has been investigated further employing natural polyelectrolytes like humic substances. Adsorption of humic acids on aluminum oxide was determined to resemble interfacial deposition on the basis of methods previously employed for the aluminum oxide/polyacrylic acid system [88]. Complexation by soluble aluminum ions produces pH drops that are very similar to that determined for polyacrylic acid, and essentially humic acids were determined to exert effects on the stability of colloidal aluminum oxide particles at pH 5 that are very similar to polyacrylic acid. 

The adsorption of natural polyelectrolytes (serum albumin-BSA) on kaolin suspensions as well as the complex formation with Na-chondroitin-6-sulfate (Na2Chs) was studied by Shimabayashi et al. by means of a microscope electrophoretic apparatus [11]. The iep of kaolin after covering with BSA was determined to be lower than that of BSA itself the zeta potential was positive at pH lower than 4.2. When the pH became higher than the iep, the zeta potential was reversed to negative values and decreased with pH. 

The in vivo stability of a natural polyelectrolyte complex membrane, such as is formed between alginate and polylysine, (or even between synthetic polyelectrolytes) must never be assumed due to slow site-by-site displacement reactions which may occur with high molecular weight polymers (proteins, etc.) present in body fluids, and to processes of hydrolysis, enzymatically promoted or otherwise which may disrupt the membrane. 

Natural organic polyelectrolytes are some of the most active components of natural soil-water systems entering into physical and chemical reactions with practically all other components of the systems. Most pesticides are strongly sorbed by insoluble natural organic polyelectrolytes, such as humic acid. The soluble humic salts, however, may solubilize insoluble pesticides. Pesticides also enter into chemical reactions with natural organic poly electrolytes. The mechanisms of most of these interactions have not yet been elucidated. Elucidation will require isolation of well-defined, chemically and physically homogeneous natural polyelectrolyte fractions. 

Shang J, Shao Z, Chtm X (2008) Electrical behavior of a natural polyelectrolyte hydrogel chitosan/carboxymethylcellulose hydrogel. Biomacromolecules 9 1208-1213... 

Many naturally occurring random-coil polyelectrolytes of a single charge type, including some carbohydrates, pectins, and keratins, are anionic and exhibit the same general surfactant interactions as their synthetic cousins. Proteins, on the other hand, are amphoteric polyelectrolytes, which possess a net charge character (anionic or cationic) that depends on the pH of the aqueous solution. Unhke most synthetic polyelectrolytes, natural polyelectrolytes such as proteins and starches often have well-defined secondary and tertiary structures in solution that can affect, and be affected by, surfactant... 

FIGURE 14.9. As natural polyelectrolytes, proteins present special problems in that their solution characteristics can change significantly with changes in pH, in the presence of electrolytes, or npon interaction with surfactants, especially charged materials. 

Zhang, J., Senger, B., Vautier, D., Picart, C., Schaaf, P., Voegel, J.C. and Lavalle, P. 2005b. Natural polyelectrolyte films based on layer-by layer deposition of coUagen and hyaluronic acid. Biomatenals 26 3353-3361. 

This chapter describes the main properties and methods for the characterization of polyelectrolytes derived from the biomass. The most important sources are plants, with cellulose and starch, which turn to polyelectrolytes after chemical modifications. CarboxymethylceUulose is the main cellulose derivative used in many industrial applications as good thickener and hydrophilic polymer for aqueous media. Cationic starches are mainly used in the paper industry for fiUa- retention or paper wet-strength. Natural polyelectrol5des are produced by algae with anionic alginates and carrageenans as the major representatives, which are used in food applications and for biomedical devices. In this respect, alginates are often associated in an electrostatic complex with a pseudo-natural polyelectrolyte (chitosan), a cationic polymer extracted from crustaceous shells. 

The second part describes recent information on the properties and biological effects of already well-known natural polyelectrolytes such as heparin and DNA and recently developed polymers such as pyran and polyionenes. The effects of polyanions and polycations on normal and transformed cells as well as on acetylcholine receptors follow. This part is of particular interest to scientists involved in biological research. 

For natural polyelectrolytes and polypeptides, the term transition means the passage from an ordered state (e.g. helix for poly-L-glutamic acid) to a disordered one under the influence of different factors i.e. chemical agents, temperature, ionization. 

Several recent reviews deal with the fundamental self-assembly between proteins and natural polyelectrolytes, e.g. DNA and polysaccharides [30, 31, 34, 111], The applications in the food sector of protein and polysaccharide complexes and coacervates are also well covered elsewhere [35,112]. Given these abundant recent reviews, this field is deliberately excluded from the present review. 

PEC nanoparticles can be easily prepared by controlled mixing of diluted polycation and polyanion solutions, which may consist of natural polyelectrolytes. Their size typically ranges between 20 and 500 nm, and they can have spherical, rod-like, or toroid shapes and can have a loose gel-like up to compact internal slmcture. 

K. (2001) The synthesis and the electric-responsiveness of hydrogels entrapping natural polyelectrolyte. Radiat. Phys. Chem., 61, 49-54. 

The temperature of the solution has both the effect of increasing its evaporation rate and reducing the viscosity of the polymer solution, thus enabling the polymer solution which was spinnable under room temperature to be electrospun easily. For example, the hyaluronic acid is a natural polyelectrolyte that is hard to be electrospun under room temperature [27]. Li et al. [83] used the high electrospinning temperature that was higher than the gel temperature of hyaluronic acid (40 °C) and thus successfully fabricated hyaluronic acid composite nanofibers with uniform morphology. Similar method was also suitable for the fabrication of other natural... 

In the last 10 years, there was a significant increase in the number of jobs that are intended to address the formation, the knowledge and molecular mechanism of these complexes, especially when involving natural polyelectrolytes. All the experience gained allowed the development of scaling methodologies applicable to macromolecules, especially enzymes with application in biotechnological processes. 

Natural polyelectrolytes such as nucleic acids, proteins and polysaccharides have also been used for LbL Studies involving natural... 

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