Chitosan acetic acid

HM pectin/sucrose systems Schizophyllan/sorbitol Xanthan/aluminum Xanthan/carob gum mixtures Alginate/calcium Chitosan/acetic acid-water-propanediol... 

Bai, R.K., Huang, M.Y., and Jiang, Y.Y. 1988. Selective permeabilities of chitosan-acetic acid complex membrane for oxygen and carbon dioxide. Polymer Bull. 20, 83-88. 

Hu and coworkers [126, 127] firstly developed an in situ precipitation approach to fabrication of 3D ordered chitosan rods with a structure of concentric circles through the formation process illustrated in Fig. 11. Briefly, the chitosan/acetic acid solution is filled into a bag made of chitosan membrane, and then immersed into 5% NaOH aqueous solution. When OH ions from the outside solution permeate into... 

On the other hand. Furze et al. [78] observed that using abiotic compounds on D. stramonium hairy roots the sesquiterpenoid phytoalexin production was elicitated but no response was observed on tropane alkaloids production [78], Also, Pitta-Alvarez et al. [42, 45] reported that B. Candida hairy roots responded positively to different elicitors. Among them it can be mentioned chitosan, acetic acid and citric acid. These compounds promoted the release of alkaloids to the culture medium [42],... 

Pitta-Alvarez, S. 1. and Giulietti, A. M. (1999) Influence of chitosan, acetic acid and citric acid on growth and tropane alkaloid production in transformed roots of Brugmansia Candida. Effect of medium pH and growth phase. Plant Cell Tissue and Organ Culture. 59, 31-38. 

Okuyama, K., Noguchi, K., Hanafusa, Y, Osawa, K., and K. Ogawa. 1999. Structural study of anhydrous tendon chitosan obtained via chitosan/acetic acid complex. International Journal of Biological Macromolecules... 

Chitosan solntion was prepared in acetic acid solution (chitosan acetic acid = 5 4). Starch powder was mixed with glycerol homogenously with the above prepared chitosan solution to form 15% starch and chitosan s isoUd gel-like mixtures by heating at lOO C for 2h. The gel-like mixtures in hot state were cold pressed to prepare wet starch/chitosan films. 

Liu et al. prepared chitosan coated cotton fiber by the reaction between aqueous chitosan acetic acid and oxidized cotton fiber. Since the chemical reaction activity of the amino group is greater than the hydroxyl group of cellulose, the fiber has potential for still more chemical modification. They have tried the control release of the herb medicine shikonin and obtained a good result. Potential usefulness of this fiber as a support for the controlled release of dmgs is suggested [49]. 

Vikhoreva, G. A., Rogovina, S. Z., Pchelko, O. M., and Galbraikh, L. S. The Phase State and Rheological Properties of Chitosan-Acetic Acid-Water System. Polymer Science, 43(5-6), 166-170 (2001). 

Chitosan acetic acid Electro-wet-spinning using a coagulation bath containing ethyl alcohol in aqueous sodium hydroxide. [193]... 

Cationic hydrophilic Glycol chitosan, DEAE-dextran, poly(ethyleneimine), poly(trimethylaminoethyl methacrylate) iodide salt 0.5 M acetic acid with 0.3 M NaiSO, or 0.8 M NaNO.,... 

The multiple emulsion technique includes three steps 1) preparation of a primary oil-in-water emulsion in which the oil dispersed phase is constituted of CH2CI2 and the aqueous continuous phase is a mixture of 2% v/v acetic acid solution methanol (4/1, v/v) containing chitosan (1.6%) and Tween (1.6, w/v) 2) multiple emulsion formation with mineral oil (oily outer phase) containing Span 20 (2%, w/v) 3) evaporation of aqueous solvents under reduced pressure. Details can be found in various publications [208,209]. Chemical cross-linking is an option of this method enzymatic cross-linking can also be performed [210]. Physical cross-linking may take place to a certain extent if chitosan is exposed to high temperature. 

One of the simplest ways to prepare a chitin gel is to treat chitosan acetate salt solution with carbodiimide to restore acetamido groups. Thermally not reversible gels are obtained by AT-acylation of chitosans N-acetyl-, N-propionyl- and N-butyryl-chitosan gels are prepared using 10% aqueous acefic, propionic and bufyric acid as solvents for treatment with appropriate acyl anhydride. Both N- and 0-acylation are found, but the gelation also occurs by selective AT-acylation in the presence of organic solvents. 

Charged polysaccharides can also serve as templates for the growth of metallic, semiconductor and magnetic nanoparticles. For instance, chitosan has been reported as a catalyst and stabilizing agent in the production of gold nanoparticles by the reduction oftetrachloroauric (III) acid by acetic acid. The biopolymer controls the size and the distribution of the synthesized Au nanoparticles and allows the preparation... 

Fig. 1.12 (A) Increase in surface plasmon ab- and from mixtures with lower chitosan concen-sorptionasAu nanoparticles are produced from a tration (ii) or lower HAuCI4 amount (iii) six reaction mixture containing 1 % chitosan, 1 % different self-sustained nanocomposite films acetic acid and 0.01 % tetrachloroauric (III) acid showing the control over the optical properties. (HAuCU) (B) shiftofsurface plasmon absorption Reprinted with permission from [164], 2004, for films prepared from the previous mixture (i), American Chemical Society.

The zeolites-chitosan composites were prepared by adding a known amount of zeolite (X, Y, or mordenite) into a 3 % chitosan solution in 1 % aqueous acetic acid. The zeolite powder was dispersed in the chitosan solution and stirred at room temperature during 1-2 hours. The gelling procedures were later carried out like as in the absence of zeolites. 

Chitosan CHITON Co. Ltd., Gdynia, Poland), having a deacetylation degree of 83% and viscosity (1% water solution of acetic acid, pH 3.5—4) of 20 mPas, was deposited on wool fabric pre-treated with enzymes using the pad-dry-fix method [19],... 

Fig. 11. (A) Force normalised by radius as a function of surface separation between mica surfaces in 0.01 wt.% acetic acid solution (pH 3.8). The arrow indicates a jump from a force barrier into molecular contact. (B) Forces between mica surfaces coated with chitosan across 0.01 wt.% acetic acid solution (pH 3.8). Two sets of measurements are shown. Filled and open symbols represent the forces measured on approach and separation, respectively, after 24 h of adsorption. The crosses represent the forces measured at pH 3.8 after the cycle of exposing chitosan adsorption layers for solutions of increasing alkalinity and measuring forces at pH 4.9, 6.2 and 9.1. The solid lines represent theoretically calculated DLVO forces. Redrawn with permission from Ref. [132]. 1992, American Chemical Society.

The /3(1— 4) linkage is relatively resistant to hydrolysis, so the major site of hydrolysis is that of the N-acetyl group to yield poly(ar-D-glucosamine) and acetic acid. This material is also known as chitosan . 

Several researchers [163-165] have studied simple coacervation of chitosan in the production of chitosan beads. In general, chitosan is dissolved in aqueous acetic acid or formic acid. Using a compressed air nozzle, this solution is blown... 

X. Geng, 0-H. Kwon, J. Jang. 2005. Eleetrospinning of chitosan dissolved in coneentrated acetic acid solution. Biomaterials, 26. pp. 5427-5432. 

The polymer substrate consisted of low viscosity chitosan, poly(D-glucosamine), (I), which had a Brookfield viscosity of a 120-200 cps in 1% acetic acid solution. 

Enzymatic hydrolysis is a useful method for the preparation of monomers from chitin and chitosan because the yield of monomers is greater by enzymatic hydrolysis than by acid hydrolysis. The enzyme chitin deacetylase hydrolyzes the acetamido group in the N-acetylglucosamine units of chitin and chitosan, thus generating glucosamine imits and acetic acid (Fig. 2.5). 

NaOH solution is added to chitin and refluxed under nitrogen at 115 °C for 6 h. The cooled mixture is then filtered and washed with water until the washings are neutral to phenolphthalein. The crude chitosan is purified as follows. It is dispersed in 10% acetic acid and then centrifuged for 24 h, to obtain a clear supernatant liquid. The latter is treated drop-wise with 40% NaOH solution and the white flocculent precipitate formed at pH 7. The precipitate is then recovered by centrifugation, washed repeatedly with water, ethanol, and ether, and the solid collected and air dried (Fig. 2.3)... 

Chitin and chitosan can be assayed by first-derivative UV/Vis method using phosphoric acid (85%) as solvent. The chitin and chitosan solution is heated to 60 °C for 40 min to enhance solubilization and then incubated in diluted solutions at 60 °C for 2 h, and the first-derivative absorption is measured at 203 nm (Fig. 2.31). The developed method was reported to be useful for the determination of DA in the whole range (20-90%). Similar wavelength selection was made in a previous study where a wavelength of 202 nm was used, when acetic acid was used as a solvent. 

FIGURE 2.J5 The 400-MHi H NMR spectra at 70 for (A) chitosan with DD 100%, (B) chitosan with DD = 87%, (C) chitosan with DD S 48% (the peak at 2.41 ppm originates from acetic acid). The small peak at 2.36 ppm originates from the acetyl protons of chitosan. The RMS for the signal to noise ratio for this peak is about 3.1. 

The ultrasonic degradation of Chitosan (deacetochitin, found in crab shells) was studied by another research group [35], Chitosan was degraded in acetic acid at 60 °C under ultrasonic irradiation. The viscosity of the Chitosan decreased by 80% after irradiation for 15 h, compared with 55% decrease by reflux under acid condition for 24 h. This was taken as evidence that the degradation under sonication is faster, purer, and more complete than under conventional conditions. 

Duan B et al (2004) Electrospinning of chitosan solutions in acetic acid with poly(ethylene oxide). J Biomater Sci Polym Hd 15(6) 797-811... 

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