Molecular weight manipulation of chitosan I: kinetics of depolymerization by nitrous acid

Allan, G. G.; Peyron, Mark

doi:10.1016/0008-6215(95)00207-a

Cited by 190 publications

(102 citation statements)

References 36 publications

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“…A fully deacetylated chitosan (F A o0.001) was depolymerized with nitrous acid 42 to obtain samples with number average DPn of 25 and 18, respectively, as determined by 13 C-NMR. 43 The DPn18 sample was subsequently fractionated by Superdex 30 gel filtration as described previously, 25 and fractions corresponding to DP intervals of 10-14, 15-21, 22-35 and 36-50 were pooled ( Figure 1a).…”

Section: Preparation and Characterization Of Chitosan Oligomersmentioning

confidence: 99%

“…The cells were washed in preheated Optimem and 50 ml of the complex formulations (corresponding to 0.33 mg pDNA) was added per well. After 5 h incubation, A fully deacetylated chitosan (F A o0.001) was depolymerized by nitrous acid 42 to obtain samples with number average DPn of 25 and 18, respectively, as determined by 13 C-NMR. 43 e DPn18 chitosan oligomer fraction was found to be comprised of oligomers ranging from 6-to 50-mers.…”

Section: Morphological Characterization Of Chitosan Polyplexesmentioning

confidence: 99%

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Improved chitosan-mediated gene delivery based on easily dissociated chitosan polyplexes of highly defined chitosan oligomers

et al. 2004

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Section: Preparation and Characterization Of Chitosan Oligomersmentioning

confidence: 99%

Section: Morphological Characterization Of Chitosan Polyplexesmentioning

confidence: 99%

Improved chitosan-mediated gene delivery based on easily dissociated chitosan polyplexes of highly defined chitosan oligomers

et al. 2004

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“…Treatment of chitosan with nitrous acid converts glucosamine to anhydromannose, which separates itself from the polymer and dissolves in water (1). Because the glucosamine here was labeled with 14 C, it is possible to measure the percent conversion of chitin to chitosan from the amount of radioactivity solubilized by nitrous acid.…”

Section: Methodsmentioning

confidence: 99%

Two Novel Techniques for Determination of Polysaccharide Cross-Links Show that Crh1p and Crh2p Attach Chitin to both β(1-6)- and β(1-3)Glucan in the Saccharomyces cerevisiae Cell Wall

Cabib

2009

Eukaryot Cell

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Previous work, using solubilization of yeast cell walls by carboxymethylation, before or after digestion with ␤(1-3)-or ␤(1-6)glucanase, followed by size chromatography, showed that the transglycosylases Crh1p and Crh2p/Utr2p were redundantly required for the attachment of chitin to ␤(1-6)glucan. With this technique, crh1⌬ crh2⌬ mutants still appeared to contain a substantial percentage of chitin linked to ␤(1-3)glucan. Two novel procedures have now been developed for the analysis of polysaccharide cross-links in the cell wall. One is based on the affinity of curdlan, a ␤(1-3)glucan, for ␤(1-3)glucan chains in carboxymethylated cell walls. The other consists of in situ deacetylation of cell wall chitin, generating chitosan, which can be extracted with acetic acid, either directly (free chitosan) or after digestion with different glucanases (bound chitosan). Both methodologies indicated that all of the chitin in crh1⌬ crh2⌬ strains is free. Reexamination of the previously used procedure revealed that the ␤(1-3)glucanase preparation used (zymolyase) is contaminated with a small amount of endochitinase, which caused erroneous results with the double mutant. After removing the chitinase from the zymolyase, all three procedures gave coincident results. Therefore, Crh1p and Crh2p catalyze the transfer of chitin to both ␤(1-3)-and ␤(1-6)glucan, and the biosynthetic mechanism for all chitin cross-links in the cell wall has been established.The fungal cell wall protects the cell against internal turgor pressure and external mechanical injury. To fulfill these functions, it must be endowed with a resilient structure. Presumably, the cell wall strength is largely due to the cross-links that bind together its components, mainly polysaccharides, giving rise to a tightly knit mesh (6,(11)(12)(13). Interestingly, the crosslinks must be created outside the plasma membrane, because most of the polysaccharides are extruded as they are synthesized at the membrane; therefore, they do not exist inside the cell. This posits a thermodynamic problem, because there are no obvious sources of energy in the periplasmic space. About 20 years ago we proposed that the free energy may come from existing bonds in the polysaccharide chains and that the new cross-links may be originated by transglycosylation, thus creating a new linkage for each one that is broken (5).Ascertaining the mechanism of cross-link formation seemed a worthwhile endeavor, both because of the theoretical implications and because the cell wall is a proven target for antifungal compounds; therefore, more knowledge about its synthesis can be of practical interest. For this type of investigation to proceed, it was necessary to devise some method for the quantitative analysis of cell wall cross-links. We developed such a procedure for the evaluation of the proportion of cell wall chitin that is free or bound to ␤(1-3)-or ␤(1-6)glucan (4). In this methodology, chitin was specifically labeled in vivo with [ 14 C]glucosamine; cell walls were isolated, and their proteins were elim...

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“…A common synthetic rout to obtain LWCS is enzymatic degradation of CS with hydrolytic enzymes or acidic degradation by hydrochloric acid and sulfuric acid [12,13]. Recently, LWCS was also formed by oxidative degradation with some oxidative systems [14][15][16]. The degradation patterns of chitosan using O 3 and NaNO 2 Citation: Safarzadeh have been reported [14,15].…”

Section: Introductionmentioning

confidence: 99%

Highly Monodisperse Chitosan Nanoparticles Prepared by a Combined Triple-Method for Potential Use as Drug Carriers

Sadeghi¹

2017

Int J Nanomater Nanotechnol Nanomed

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Chitosan (CS) as a biodegradable polymer with unique bio-attachment properties that makes it favorable to be used in biomedical applications. Insolubility in water is the problem with use of CS. The purpose of this study was to prepare low molecular weight, water-soluble CS nanoparticles that exhibit excellent water solubility and biological, chemical, and physical functions. Oxidative degradation technique using hydrogen peroxide (H 2 O 2 ) was used to decrease chitosan molecular weight. Then ultrasonication and ionic gelation method using sodium tripolyphosphate (TPP) were used to prepare CS nanoparticles. Molecular weight of chitosan determined by Ubbelohde viscometry and it decreased by approximately 100%. From the spectral information (FTIR) it was observed that the cross-linking between CS and TPP was taking place while the main structure of chitosan was the same. The dynamic light scattering results showed that water-soluble nanoparticles had a multimodal size distribution pattern, while low molecular particles yielded monodisperse particle distribution with an average size of ~45 nm, which was directly ascribed to the role of ultrasonication process. The morphology of nanoparticles was observed by SEM and TEM techniques. The mean diameter of nanoparticles was obtained in a range of 30 nm to 45 nm with a narrow size distribution and polydispersity index smaller than 0.2. Cytotoxicity of CS nanoparticles on human umbilical valve endothelial cells (HUVEC) was assessed by CCK-8 assay, as well as "Live/ Dead" assay and subsequent fl uorescent imaging. The results showed no to minimal cytotoxicity for CS solutions up to 50 μg/ml, while sporadic dead cells observed for 100 μg/ml solutions. This suggested that our monodisperse nanoparticle systems are great candidates to be used for drug delivery systems.

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Molecular weight manipulation of chitosan I: kinetics of depolymerization by nitrous acid

Cited by 190 publications

References 36 publications

Improved chitosan-mediated gene delivery based on easily dissociated chitosan polyplexes of highly defined chitosan oligomers

Improved chitosan-mediated gene delivery based on easily dissociated chitosan polyplexes of highly defined chitosan oligomers

Two Novel Techniques for Determination of Polysaccharide Cross-Links Show that Crh1p and Crh2p Attach Chitin to both β(1-6)- and β(1-3)Glucan in the Saccharomyces cerevisiae Cell Wall

Highly Monodisperse Chitosan Nanoparticles Prepared by a Combined Triple-Method for Potential Use as Drug Carriers

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