Chitosan quatemization

Wu J, Wei W, Wang LY, Su ZG, Ma GH (2007) A thermosensitive hydrogel based on quatemized chitosan and polyethylene glycol) for nasal drug delivery system. Biomaterials 28 2220-2232. 

Kotze, A.F., et al. 1999. Enhancement of paracellular drag transport with highly quatemized, Y-trimethyl chitosan chloride in neutral environments In vitro evaluation in intestinal epithelial cells (Caco-2). J Pharm Sci 88 253. 

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... 

Snyman, D., Hamman, J. H,. Kotze, J.S., Rollings, J.E. and Kotze, A.F. (2002) The relationship between the absolute molecular weight and the degree of quatemization of /V-trimethyl chitosan chloride. Carbohydr. Polym. 50 145-150. 

Thanou, M.M., Kotze, A.F. Scharringhausen, T., LueBen, H.L., de Boer, A.G., Verhoef, J.C. and Junginger, H.E. (2000a). Effect of degree of quatemization of A-trimethyl chitosan chloride for enhanced transport of hydrophilic compounds across intestinal Caco-2 cell monolayers. J. Control. Release 64 15-25. 

Quatemized chitosan (QCh) derivatives have a high activity against bacteria and thus are potential candidates for wound dressing applications. Electrospun QCh fiber mats were successfully prepared by electrospinning QCh solutions mixed with PVA [131]. The electrospun QCh/PVA fiber mats were stabilized against dissolution in aqueous environment using photomediated crosslinking. 

The quatemization of the primary amine was investigated [28, 29]. This chemical modification increased the solubility of chitosan in water [30], keeping chitosan soluble over a wide pH range. In addition, the cationic character [23] can be controlled and kept pH-independent, which is desirable for improving the stability of ionic complexes [31, 32]. Typically, the reaction of chitosan with methyl iodide under basic conditions is the most straightforward route for quatemizing chitosan [33]. 

Among all the quatemized chitosans described into literature, W,W,W-trimethyl chitosan chloride (TMC) is the most widely applied for gene therapy applications [28, 33, 34]. The quatemization maintained and improved the muco-adhesive properties of chitosan, depending on the quatemization degree, which makes this chitosan derivative an ideal candidate for gene delivery [23]. Typically, TMC can be synthesized by reaction of chitosan with methyl iodide in the presence of sodium hydroxide into A-methyl-2-pyrrolidinone at 60 °C. In a second step, the iodide ion is substituted by chloride by an ion exchange process [34] (Fig. 2). 

Due to its cationic properties, chitosan has been extensively used for gene delivery. However, due to its low buffering capacity and the low stability of nucleic acid-loaded chitosan nanoparticles, several chemical modifications have been introduced to improve transfection efficiency in vivo (1) quatemization to improve solubility and stability of the nanoparticles, (2) grafting of polymer chains such as PEI to improve endosomal escape, or (3) grafting of ligands for specific cell targeting. 

Xiong Y, Liu QL, Zhang QG, Zhu AM (2008) Synthesis and characfiaizatitni of cross-linked quatemized poly (vinyl alcohol)/chitosan composite anion exchange membranes for fuel cells. J Power Sources 183 447 53... 

In addition to the effect of the PEI moiety, we have also compared the effect of two chemical modification methods (A-methylene phosphonation and quatemization) on the transfectability of the CP copolymer. A-methylene phosphonation is a chemical approach to increase the water solubility of chitosan via the introduction of the phosphonic acid function (Heras et al. 2001) whereas quatemization is an old process that comprises methyl iodide-mediated N, N, A-trimethylation for the fabrication of chitosan soluble in water at the physiological pH (Thanou et al. 2002). In weighing... 

A series of quatemized carboxymethyl chitosan (CMQ), the sample no., and the characterization are listed in Table 15.1 (Sun et al. 2005). A Gram-positive bacterium S. aureus and a Gram-negative bacterium E. coli were used and inoculated on a gel containing 1% peptone, 2% agar, 3% meat extract, and 0.5% NaCl for this experiment. 

Guo et al. (2006) have synthesized A -substituted chitosan and quatemized chitosan and evaluated their antioxidative activity on hydroxyl radicals. It has been found that the antioxidative activity of quatemized chitosan derivatives was higher than that of TV-substituted chitosan derivatives. 

Uragami, T., Kato, T., Nagayasu, H., and Yura, I. 1993a. Transport of nucleic acid bases against their concentration gradients through quatemized chitosan membrane. Carbohydr. Polym. 21 289-293. 

Uragami, T., Takuno, M., and Miyata, T. 2002a. Evapomeation characteristics of cross-linked quatemized chitosan membranes for the separation of an ethanol/water azeotrope. Macromol Chem. Phys. 203 1162-1170. 

Uragami, T., Tanaka, Y, and Nishida, S. 2002b. Permeation and separation under high temperature and high pressure for ethanol/water vapors through cross-linked quatemized chitosan composite membranes. Desalination 147 449 54. 

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