Hyperbranched polysaccharide

Furthermore, the more there is of the branched base of the polysaccharide, the greater the opportunity the grafted (onto polysaccharide backbone) poly-acrylamide/cationic moiety chain will have to form an aggregate of the contaminants. Thus, if the grafted moiety is loaded onto the most hyperbranched polysaccharides, it will have easier accessibility to form aggregates of the contaminants, providing the best flocculation characteristics. 

Figure 7.1 Synthesis of hyperbranched polysaccharide (Polyla-c) by cationic ring-opening polymerization of l,6-anhydro-j5-D-hexopyranose (la-c).

To determine the degree of branching (DB) for the hyperbranched polysaccharide, la-c were classified as latent AB4-type monomers, which have one anhydro moiety capable of ring opening and three hydroxyl groups in a molecule, even though the reactivity of their hydroxyl groups was expected to be different in each case. The DBs of Polyla-c, therefore, can be... 

Satoh, T, Imai, T., Ishihara, H. etal. (2003) Synthesis of hyperbranched polysaccharide by thermally induced cationic polymerization of l,6-anhydro-P-i)-maimopyranose. Macromolecules, 36,6364—6370. 

Tao, Y Zhang, L Yan, F Wu, X. Chain conformation of water-insoluble hyperbranched polysaccharide from fungus. Biomacromolecules, 2007, 8, 2321-2328. 

CHITOSAN AS POLYSACCHARIDE SCAFFOLD TOWARD HYPERBRANCHED SIALOSIDES... 

C. Decomposition was complete at 600°C. As shown in Figure 2, the thermal decomposition of 10 occurred gradually with 65% residual weight still observable at 600°C. The TGA curves of 9 and 10 indicated that the thermal stabilities of the present hyperbranched aminopolysaccharides were much higher than those of normal linear polysaccharides. For example, chitin showed a significant weight loss at 275 28°C. 

The subject of this review is complexes of DNA with synthetic cationic polymers and their application in gene delivery [1 ]. Linear, graft, and comb polymers (flexible, i.e., non-conjugated polymers) are its focus. This review is not meant to be exhaustive but to give representative examples of the various types (chemical structure, architecture, etc.) of synthetic cationic polymers or polyampholytes that can be used to complex DNA. Other interesting synthetic architectures such dendrimers [5-7], dendritic structures/polymers [8, 9], and hyperbranched polymers [10-12] will not be addressed because there are numerous recent valuable reports about their complexes with DNA. Natural or partially synthetic polymers such as polysaccharides (chitosan [13], dextran [14,15], etc.) and peptides [16, 17] for DNA complexation or delivery will not be mentioned. 

Although the structure of polysaccharides such as dextrane and glycogen was identified to be hyperbranched already in the 1930 s and Flory introduced his theoretical work on random AB polycondensates in the early 1950 s, only since the beginning of the 1990 s a rapidly increasing interest in dendritic and hyperbranched polymers can be noticed. 

---