Polymers chitosan

More recently chitosan polymers which are derivatives of chitin materials have evoked interest due to their bioactivity and biodegradability. For example, N-carboxybutyl chitosan has been show to effectively promote wound healing (9). Acetate, and butyrate derivatives of chitosan have decreased blood clotting time significantly (10). 

In vitro and ex vivo intestinal tissue models to measure mucoadhesion of poly (methacrylate) and N-trimethylated chitosan polymers. Pharmaceutical Research, 22, 38-49. 

The term chitosan describes a series of chitosan polymers with different molecular weight (MW), viscosity, and degree of deacetylation (DD) (40-98%). It is a linear polyamine with a number of amino groups that are readily available for chemical reaction and salt formation with acids. 

When calculating the theoretical force curves shown in Fig. 9 we used the XPS results to obtain the value of s and twice the length of the polymer brush was set to 23 nm. The anchoring points for the grafted PEO-chains were set at a distance 1.5 nm away from the mica surface. This value was chosen to be equal to the undisturbed layer thickness of the adsorbed chitosan polymer without grafted side-chains. When the prefactor is set equal to 1, the lower curve in Fig. 9 is obtained, and when a prefactor equal to two is used the upper curve is obtained. 

Kumar, G., Bristow, J.F., Smith, P.J., and Payne, G.R 2000. Enzymatic gelation of the natural polymer chitosan. Polymer, 41 2157-2168. 

Some of the most promising systems for the controlled release of proteins and peptides involve encapsulation or entrapment in biocompatible polymeric materials. The most widely used polymers to date are poly(ethylene glycol) (PEG), (D,L)-poly(lactic glycohc acid) (PLGA), poly(lactic acid) (PLA) and chitosan. Polymers could be attached to the protein to incTease the overall molecular weight of the system and so reduce the rate of absorption across the epithehum of the alveoh, or the protein could be encapsulated in the polymeric system and slowly released into systemic circulation. 

Owing to its free amine functions, chitosan may also be protonated (pfCa = 5.6). In in vitro studies with Hela-cells, chi-tosan/DNA complexes showed a gene-transfection potency similar to that reported for PEI/DNA complexes. Plain chitosan, however, is almost insoluble in water at neutral pH (but soluble at acidic pH), for this reason, trimethylated, quaternary chitosan derivatives have been produced that are sufficiently soluble under physiological conditions and easily complex DNA molecules. In in vitro experiments with COS-1 and CaCo-2 cells, these innovative chitosan derivatives proved superior to nontreated chitosan polymers, particularly as they showed no unspecific cytotoxicity [87]. 

Rhazi M et al (2000) Investigation of different natural sources of chitin influence of the source and deacetylatino process on the physicochemical characteristics of chitosan. Polym Int 49 337-344... 

Chitosan Have inherent antibacterial activity some members have been found hemotoxic whether chitosan polymers are totally biodegraded in an animal body is still not known. 

CD/chitosan polymer can be prepared using EPI as the crosslinking agent under the protection of benzaldehyde on amino. This polymer retained the free amino of chitosan and added the hydrophobic cavity of CD. Adsorbability is superior to chitosan. 

Keely, S. Rullay, A. Wilson, C. Carmichael, A. Carrington, S. Corfleld, A. Haddleton, D.M. Brayden, D.J. In vitro and ex vivo intestinal tissue models to measure mucoadhesion of poly methacrylate and N-trimethylated chitosan polymers. Pharm. Res. 2005, 22 (1), 38-49. 

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