Molecular weight of chitosan

Chitosan microparticles were prepared with tripolyphosphate by ionic cross-hnking, starting from chitosan acetate 1% and oil as an emulsion in the presence of the surfactant Tween-80 2% the o/w 1 10 emulsion was introduced into tripolyphosphate solution by a spray gun. The microparticles were then washed their sizes were in the 500-710 jim range. As the pH of tripolyphosphate solution decreased and the molecular weight of chitosan increased, the microparticles had a more spherical shape and smoother surface [98]. 

Effect of Molecular Weight of Chitosan and Its TBA Conjugate on Mucoadhesive Potentials... 

Chitosan is a biodegradable polysaccharide and has been shown to interact with the phosphate groups of DNA, condensing plasmids into spherical and toroidal particles. The colloidal and surface properties of plasmid/chitosan complexes have been shown to depend on the molecular weight of chitosan, the ratio of plasmid to chitosan and the preparation medium. Smaller nanoparticles have been observed with low molecular weight chitosan (2 kDa) as compared to high molecular weight chitosan (540 kDa). A number of cell lines have been transfected with plasmid/chitosan complexes. 

Ishii et al. [64] explained the transfection mechanism of chitosan/DNA complexes in relation to cell uptake. They used fluorescein isothiocyanate-labeled plasmid DNA and Texas Red-labeled chitosan. They found that the transfection of chitosan/DNA complexes was higher with the molecular weight of chitosan at 40 or 84 kDa and N/P ratio at 5 (Figure 20.4). The transfection... 

On the other hand, literature studies report that the survivability and stability of probiotic bacteria loaded into chitosan-coated alginate microcapsules are largely dependent on the molecular weight of chitosan. ° Thus, the microcapsules prepared with high molecular weight chitosan provided a higher survival rate (46%) compared with the microcapsules made with low molecular weight chitosan (36%). ... 

The molecular weight of chitosan is another important property that determines its suitability for a particular application. It determines the viscosity of its solution and the strength of chitosan fiber and film. The molecular weight of chitin and chitosan depends on its source and deacetylation conditions [time, temperature, and concentration of NaOH], respectively [1, 4]. Molecular weight of chitosan determined by various methods such as viscometry [28], gel permeation chromatography [29] and light scattering spectrophotometry [30]. 

Incorporation of sodium acetate has been found to drop the viscosity of chitosan solution (Fig. 19.16) [50]. The effect of electrolyte was observed to be more pronounced on high-molecular-weight chitosan, CHT-MC. With decrease in molecular weight of chitosan, the amount of sodium acetate required to attain a minimal viscosity was decreased. The decrease in viscosity with increase in electrolyte concentration can be attributed to the shielding effect... 

Hebeish, A., Waly, A., and Aou-Okeil, A., The effect of molecular weight of chitosan on cotton fabric treated with citric acid and its impact on dyeing with some acid dyes,/. Text. Assoc., 65(5), Jan-Feb (2005), 219-227. 

The most popular method to measure the molecular weight of chitosan is viscometry, which is based on the Mark-Houwink equation... 

R.A. Muzzarelli, C. Lough, M. Emanuelli, The molecular weight of chitosans studied by laser light-scattering, Carbohydr. Res. 164 (1987) 433 42. 

Nguyen, S., Winnik, F.M. and Buschmann, M.D. (2009) Improved reproducibility in the determination of the molecular weight of chitosan by analytical size exclusion chromatography. Carbohydrate Polymers, 75, 528-533. 

Tangsadthakun, C., Kanokpanont, S., Sanchavanakit, N., Pichyangkura, R., Banaprasert, T, Tabata, Y, and Damrongsakkul, S. The influence of molecular weight of chitosan on the physical and biological properties of coUagen/chitosan scaffolds. J Biomater Sci, Pofym Ed, 18,147-163 (2007). 

Viscosimetry is the mostly utilized method to determine the molecular weight of chitosan due to its simplicity. The method has the disadvantage of not being absolute because it relies on the correlation between the values of intrinsic viscosity with those of molecular weight, as determined hy an absolute method for fractions of a given polymer. This relationship is given by the well-known Mark—Houwink—Sakurada equation. 

Rong, H. C. and D. H. Homg. 1996. Effect of molecular weight of chitosan with the same degree of deacetylation on the thermal, mechanical, and permeability properties of the repaired membrane. Carbohydrate Polymers 29 353-358. 

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