Polysaccharide polyelectrolytic behavior

Crescenzi, V., Dentini, M., and Rizzo, R., 1981a, Polyelectrolytic behavior of ionic-polysaccharides, "Solution Properties... 

More than half a century ago, Bawden and Pirie [77] found that aqueous solutions of tobacco mosaic virus (TMV), a charged rodlike virus, formed a liquid crystal phase at as very low a concentration as 2%. To explain such remarkable liquid crystallinity was one of the central themes in the famous 1949 paper of Onsager [2], However, systematic experimental studies on the phase behavior in stiff polyelectrolyte solutions have begun only recently. At present, phase equilibrium data on aqueous solutions qualified for quantitative discussion are available for four stiff polyelectrolytes, TMV, DNA, xanthan (a double helical polysaccharide), and fd-virus. 

Polyelectrolyte solutions have been investigated much more extensively in aqueous solutions than in nonaqueous solutions [1-5]. Since many polyelectrolytes, usually with high charge density, are difficult to dissolve in polar organic solvents, and since there is a great interest in biological polyelectrolytes [6-8] such as proteins, nucleic acids, and polysaccharides in aqueous solutions, the aqueous solution behavior of polyelectrolytes has become a main subject of study. 

The development of the electrochemistry of biopolymers has paralleled research on their structures. In the case of proteins the basic research by the polarography school of Heyrovsky and the electrophoresis school of Tiselius and Theorell started in the thirties, whereas research on nucleic acids and polysaccharides was the focus of interest about 20 years later at Jena and Brno. The study of the behavior of proteins and nucleic acids as polyelectrolytes in solution is now a very broad field and the main topics of research are... 

Anionic polysaccharides respond in similar fashion to surfactants. They are relatively unaffected by anionic surfactants like sodium or ammonium lauryl sulfate. On the other hand, they form strong ionic complexes with cationic surfactants like dodecyltrimethylam-monium chloride, even at cationic surfactant concentrations below the critical micelle concentration (cmc), or concentration at which the surfactant molecules form micelles in solution (92,93). The behavior of polyelectrolytes in the presence of surfactants is summarized in Chapter 5 and has been reviewed (94). 

Section II is devoted exclusively to polysaccharide systems, but includes a fairly broad variety of polymers and applications. Kennedy et al. describe some industrially important polysaccharides, while Morris covers various bacterial-derived polysaccharides used in the food and agricultural industries. Carraher et al. describe some tin modified dextrans in the third Chapter of this Section. Some acidic, heparin-like, polysaccharides are described in the following Chapter (Linhardt, et al.) then Kobayashi reveals some cellulose derivatives which form liposomes and membranes. The final three papers of this Section deal with chitin and chitosan systems. Alkaline chitosan gels are presented by Hirano et al. Kikuchi and Kubota then describe some polyelectrolytes derived from chitosan derivatives. Finally, Seo and lijima consider the sorption behavior of chitosan gels. 

As has been discussed earlier biological polyelectrolytes are commonly available as nucleic acids, polyamino acids and polysaccharides. In this section, we shall discuss the aqueous state behavior of three representative biopolymers DNA (a nucleic acid), gelatin (a polyamino acid) and cellulose (a polysaccharide). The solution properties of biopolymers have many dimensions and the least discussed feature is their persistence length. This is a length scale that plays a central role in governing intermolecular interactions. Hence, herein the focus has been centered around the evaluation of persistence length of the aforesaid biopolymers from experimental data. 

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