Chitosan oligomers

Chitosan and depolymerized chitosan oligomers as condensing carriers for in vivo plasmid delivery. Journal of Controlled Release, 56, 259-272. 

A chitosan oligomer film was used as an active coating for the immobihza-tion of ssDNA at a GC electrode. Chitosan oligomer is a kind of /1-1,4-linked... 

MacLaughlin, F.C., Mumper, R.J., Wang, J., et al. (1998). Chitosan and depolymer-ized chitosan oligomers as condensing carriers for in vivo plasmid delivery. J. Control Release, 56, (1-3), 259-272. 

Uchida, Y., Izume, M., and Ohtakara, A. (1989). Preparation of chitosan oligomers with purified chitosanase and its application. In "Chitin and Chitosan", (G. Skjak-Braek,... 

Thanou M, Florea BI, Geldof M et al (2002) Quatemized chitosan oligomers as novel gene delivery vectors in epithelial cell lines. Biomaterials 23 153-159... 

Interfacial Properties of Chitosan-PEO Graft Oligomers Surface Competition with Unmodified Chitosan Oligomers... 

The solubility problems associated with chitin and chitosan may limit their use in physiological and functional foods. The intestines of most animals lack the ability to produce chitinase and chitosanase. These two enzymes have the ability to hydrolyze chitin and chitosan, respectively. Therefore, they will be excreted unchanged in the feces. On the other hand, chitin and chitosan oligomers are considered to have more physiological functions because they are water soluble and their solutions are less viscous, so they are readily absorbed in the human intestine (Jeon et al., 2000). 

Chitosan oligomers were first prepared by Horowitz et al. (1957). They demonstrated that acid hydrolysis of chitosan with concentrated HC1 leads to the production of chitosan oligomers with a low degree of polymerization (DP), but in a quantitative manner. 

Several studies have described the production of chitosan oligomers with a DP of less than six residues (Sakai et al., 1990 Takahashi et al., 1995 Tsukada and Inoue, 1981). On the other hand, Domard and Cartier (1989) reported that a wide distribution of glucosamine oligomers could be easily produced and separated up to a DP of 15 in the pure form. Defaye et al. (1994) prepared chitosan oligomers by fluorolysis in anhydrous hydrogen fluoride. They obtained oligomers with a DP of 2-11. 

Most acidic hydrolysis methods have reported production of chitosan oligomers with a low DP, mainly from monomer to tetramer in quantitative amounts. The yields of relatively higher DP (pentamer to heptamer) oligomers were low. However, physiological function is rendered best by high DP oligomers. 

N-Acetylglucosamine Glucosamine Chitosan oligomers Chitin oligomer... 

Chitosan has been reported to cause significant hypocholesterolemic activity in different experimental animals (Hirano et al., 1990 Sugano et al., 1978, 1980 Ylitalo et al., 2002). Sugano et al. (1988) noted that chitosan oligomers did not exhibit this effect. The studies were carried out on rat groups fed on a diet rich in cholesterol to find the effect of chitosan hydrolysates with different MWs and viscosity on the hypocholesterolemic activity. The lower the MW of chitosan, the better its cholesterol-lowering potential. 

Jeon, Y.-J., Shahidi, F., and Kim, S.-K. 2000. Preparation of chitin and chitosan oligomers and their applications in physiological functional foods. Food Rev. Int. 16, 159-176. 

Figure 20.6 Transfection efficiencies in COS-1 cells obtained with chitosan oligomer, trimethylated chitosan oligomers and DOTAP (N-[l-(2,3-dioleoyloxy)propyl]-N,N, N-trimethylammonium sulphate)/DNA complexes at different weight/weight ratios. Values are mean + S.D (n=3). Source From Ref. [69].

Einbu A, Grasdalen H et al (2007) Kinetics of hydrolysis of chitin/chitosan oligomers in concentrated hydrochloric acid. Carbohydr Res 342 1055-1062... 

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