Polyelectrolyte biological anionic

The extraordinary properties of heparin as a mixture of biological anionic polyelectrolytes are important in understanding its action as a drug. These properties are (1) chemically it consists of multiple chains... 

Synthetic examples include the poly(meth)acrylates used as flocculating agents for water purification. Biological examples are the proteins, nucleic acids, and pectins. Chemically modified biopolymers of this class are carboxymethyl cellulose and the lignin sulfonates. Polyelectrolytes with cationic and anionic substituents in the same macromolecule are called polyampholytes. 

Significant research has been directed toward the use of polyelectrolyte complexes as blood compatible materials. Several investigators found that water-insoluble polyelectrolyte complexes can suppress blood coagulation [487-490]. Davison and coworkers reviewed and studied the biological properties of water-soluble polyelectrolyte complexes [491] between quatemized poly(vinyl imidazole) or polyvinyl pyridine) and excess sulfonated dextran or poly(methacrylic acid). By forming complexes with a stoichiometric excess of anionic charge, a more compact conformation with anionic character was obtained. 

The synthesis of polypyrrole-heparin nanotubes was performed at a constant potential of 0.8 V (vs. SCE), using a nanoporous membrane as a template [71]. Heparin, which is a bioactive polyelectrolyte, was used as the doping anion. The use of a bioactive doping compound, which provides interesting biological properties in the composite sample, allows the fabrication of functionalized surfaces able to promote direct electronic communication between biological species and substrates. This result also confirmed that the... 

Ions, defined as particles that carry electrical charges, exist in condensed phases (solids and liquids) as electrically neutral combinations of cations and anions electrolytes. The ions may be bound or relatively free to migrate. Ions may be monatomic, such as K+or Cr, they may consist of a few atoms, such as ammonium, NH4+, or sulfate, S04 , or even considerably more than a few, such as nitrobenzoate, 02NC6H4C02, or tetrapropylammonium, (C3H7)4N+. They may even consist of very many atoms and may carry many dispersed charges and are then referred to as poly-ions, constituting the dissociated part of polyelectrolytes. Some biological moieties, such as polypeptides, proteins, and nucleic acids, as well as suitable synthetic molecules are examples of polyelectrolytes. 

Finally, we cite as examples of multilayers based on interactions other than electrostatic ones, protein multicomponent films, based on specific interactions between the biological molecules or between these biological molecules and polyelectrolytes. For example, immunoglobulin G can be assembled with the anionic poly(styrene sulfonate) (PSS) at pH values above and below its isoelectric... 

Electrostatic immobilization employs similar complementarity. The fiber surface can be coated with a thin polyelectrolyte membrane, which interacts electrostatically with oppositely charged sensing materials. For example, a negative surface, such as sulfonated polystyrene, can be prepared to efficiently immobilize a positively charged dye. Similarly, cationic polymers can bind various anions. Ionic indicators or biological molecules (i.e., either cations or anions) can be immobilized by electrostatic interaction. 

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