Polysaccharide-based polymers

Proteins are mostly separated by CZE. Strong interactions between the analyte molecules and the capillary wall that are predominately electrostatic in nature have a strong influence on separation efficiency. By the use of buffer additives like amines or the use of dynamically or permanently coated capillaries, highly efficient separation of proteins in CZE is achievable. Here, the native proteins with their tertiary structure are separated. Denatured proteins as SDS complexes can be separated in gels. Advantageous are polysaccharide-based polymers, because they permit UV detection at low wavelength (214 nm), impossible with acrylamide-based gels. A separation of SDS-denatured protein standards in a dextran gel is shown in Fig. 7. 

Polysaccharide-based polymers (eg, chitosan, starch, alginate, HA, dextran) show interesting properties such as good hemocompatibihty, good interactions with cells, nontoxicity and lower cost with respect to other biopolymers such as collagen, thereby justifying their use as scaffold materials in TE apphcations. 

Polysaccharide based polymer beads packed in tile column... 

Natural Polymers of Plant Origin Polysaccharide Based Polymers... 

Carbohydrates are classified based upon the products formed when they are hydrolyzed. Monosaccharides are simple sugars that cannot be broken down into simpler sugars upon hydrolysis. Examples of monosaccharides are glucose, ribose, deoxyribose, and fructose. Disaccharides contain two monosaccharide units and yield two monosaccharides upon hydrolysis. Examples of disaccharides are lactose, maltose, and sucrose. Polysaccharides are polymers of monosaccharide units and yield many individual monosaccharides upon hydrolysis. Examples of polysaccharides are starch, glycogen, and cellulose. 

Brine composition and polymer type should be considered together, and could lead to improved control of the viscosity of polysaccharide based drilling fluids. 

Although the pyrolysis of some classes of polysaccharide materials has been studied quite extensively in the food, petrol and tobacco industry, very little has been published specifically on polysaccharide binders (arabic gum, tragacanth gum, fruit tree gum, honey and starch). The pyrolysis of glucane based polymers, especially cellulose, has been studied in detail [6,55], highlighting how anhydrosugars and furan derivatives are the main pyrolysis products, together with one-, two- and three-carbon aldehydes and acids. 

Chiral separations result from the formation of transient diastereomeric complexes between stationary phases, analytes, and mobile phases. Therefore, a column is the heart of chiral chromatography as in other forms of chromatography. Most chiral stationary phases designed for normal phase HPLC are also suitable for packed column SFC with the exception of protein-based chiral stationary phases. It was estimated that over 200 chiral stationary phases are commercially available [72]. Typical chiral stationary phases used in SFC include Pirkle-type, polysaccharide-based, inclusion-type, and cross-linked polymer-based phases. 

Different classifications for the chiral CSPs have been described. They are based on the chemical structure of the chiral selectors and on the chiral recognition mechanism involved. In this chapter we will use a classification based mainly on the chemical structure of the selectors. The selectors are classified in three groups (i) CSPs with low-molecular-weight selectors, such as Pirkle type CSPs, ionic and ligand exchange CSPs, (ii) CSPs with macrocyclic selectors, such as CDs, crown-ethers and macrocyclic antibiotics, and (iii) CSPs with macromolecular selectors, such as polysaccharides, synthetic polymers, molecular imprinted polymers and proteins. These different types of CSPs, frequently used for the analysis of chiral pharmaceuticals, are discussed in more detail later. 

Many ATPS systems contain a polymer which is sugar based and a second one which is of hydrocarbon ether type. Sugar-based polymers include dextran (Dx), hydroxy propyl dextran (HPDx), FicoU (Fi) (a polysaccharide), methyl cellulose (MC), or ethylhydroxyethyl cellulose (EHEC). Hydrocarbon ether-type polymers include poly (ethylene glycol) (PEG), poly (propylene glycol) (PPG), or the copolymer of PEG and PPG. De-rivatized polymers can also be useful, such as PEG-fatty acids or di-ethylaminoethyl-dextran (Dx-DEAE). 

We have seen that polysaccharides are polymers composed of a single type of monomer (carbohydrates), as are proteins (amino acids). The third type of hiopolymer is more complex. Nucleic acids use three very different types of monomers the phosphate group, one of two simple carbohydrate units (deox)tribose or ribose), and selected organic bases (Figure 28-15). A typical segment of the resulting polymer is shown in Figure 28-16. 

The drive towards microencapsulation systems based on the use of synthetic hydrophilic methacrylate based polymers is fueled by their proven biocompatibility, (56) hydrolytic stability, (57) ease of synthesis (66, 67) and enormous structural diversity made possible through copolymerization. In contrast, interest in polysaccharide gel formers such as alginate is founded upon the relative ease of capsule formation under physiological conditions. It would seem inevitable that attempts be made to combine the host biocompatibility and stability of methacrylate based polymers with the ease of capsule formation... 

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