NMR and FT Raman characterisation of regioselectively sulfated chitosan regarding the distribution of sulfate groups and the degree of substitution

Zhang, Kai; Helm, J.W.; Peschel, Dieter; Грүнер, Маргит; Groth, Thomas; Fischer, Steffen

doi:10.1016/j.polymer.2010.08.034

Cited by 62 publications

(51 citation statements)

References 46 publications

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“…In the spectrum of chitosan ( Fig. 1 (a) 40 In the spectrum of 4a (Fig. 2 (b)), the new signals were observed at 61.6 and 55.0 ppm, which were assigned to two kinds of methylene carbon in EDTA moiety.…”

Section: Characterization Of Water Soluble Ed-chmentioning

confidence: 99%

Water soluble EDTA-linked chitosan as a zwitterionic flocculant for pH sensitive removal of Cu(ii) ion

Fujita

Sakairi

2016

RSC Adv.

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A linear and non-crosslinked polymer, EDTA-linked chitosan (ED-ch), was synthesized by N-acylation of chitosan with EDTA (ethylenediaminetetraacetic acid) monoanhydride under from acidic to slightly basic aqueous conditions. The degree of substitution (D.S.) of EDTA residues in the product was changeable by the stoichiometry of the acylation reagent, and the structure was confirmed by elemental analysis, FT-IR, 1 H and 13 C NMR spectroscopy. The newly introduced functional group in ED-ch provided properties as a strong chelating reagent and an amphoteric polyelectrolyte. It was found that ED-ch had good water solubility in both acidic and basic region and precipitated in the narrow pH region. Applicability of ED-ch to removal of heavy metal ions by flocculation was proven by a model experiment using 10 ppm Cu(II) solution.Simple procedure, mixing ED-ch with D.S. 41% and 70%, and subsequent pH adjustment (4.5 and 2.5) and centrifugal separation of the flocs formed, was shown to remove almost complete Cu(II) from aqueous solution, respectively. The residual Cu(II) concentration after these flocculation/separation process with ED-ch reached 0.03 ppm.

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Section: Characterization Of Water Soluble Ed-chmentioning

confidence: 99%

Water soluble EDTA-linked chitosan as a zwitterionic flocculant for pH sensitive removal of Cu(ii) ion

Fujita

Sakairi

2016

RSC Adv.

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“…The sulfation reaction of chitosan can produce derivatives such as 6-O-sulfate, 3,6-O sulfate, N-sulfate (sulfate at amino group at C-2) and N, 6-O-sulfate (Gamzazade et al, 1997;Holme & Perlin, 1997;Zhang et al, 2010Zhang et al, , 2011. The HSQC spectrum for the chitosan-S-0.67 sample is shown in Fig.…”

Section: Nuclear Magnetic Resonancementioning

confidence: 99%

“…5. The 13 C/ 1 H correlation for C-6/H-6 shows a low intense signal at ı60.6/4.0, 3.7 due to C/H-6 without the sulfate group and new signals at ı67.0/4.3 and ı66.6/4.1 assigned to sulfated C-6 (Gamzazade et al, 1997;Holme & Perlin, 1997;Zhang et al, 2010Zhang et al, , 2011. The C-2 amino carbon of chitosan-S-0.67 shows three different correlations on the HSQC spectrum in the region of ı55.7 and ı56.7.…”

Section: Nuclear Magnetic Resonancementioning

confidence: 99%

Sulfated chitosan as tear substitute with no antimicrobial activity

Pires

Cunha

Maciel

et al. 2013

Carbohydrate Polymers

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Chitosan of high molar mass and with 82% deacetylation was sulfated using two procedures and characterized. In the first method sample chitosan-S1 was produced using chlorosulfonic acid as the sulfating agent and N,N-dimethylformamide as the medium, and in the second method (chitosan-S2) formic acid was also used. The degrees of sulfation were 0.87 (chitosan-S1) and 0.67 (chitosan-S2). FTIR spectra showed bands at 1230, 800 and 580 cm(-1), attributed to sulfation. Moisture content followed the order: chitosan-S-0.87>chitosan-S-0.67>chitosan. Chain depolymerization was verified by GPC. Aqueous solutions showed pseudoplastic behavior and the viscosity at a concentration of 0.3% (w/v) was higher than that of healthy human tears (close to 3 mPas at shear rate 130 s(-1)). Substitutions in the C2NH and in C6OH groups were verified by NMR. Antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa was not observed. Considering that chitosan-S-0.67 had a higher solubility, less chain depolymerization, higher yield and better thermal stability in comparison with chitosan-S-0.87, the derivative with DS 0.67 offered the greatest potential for use in formulations of tear substitutes.

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“…These signals also can be found at the same chemical shift in the spectrum of quaternary ammonium chitosan sulfates. Some new characteristic peaks at ı 3.75-3.22, ı 2.70 and ı 2.79 ppm present due to partial sulfonation of primary hydroxyl group and amino group in the spectrum of quaternary ammonium chitosan sulfates, but they absent from the spectrum of quaternary ammonium chitosan [30,31]. Fig.…”

Section: Resultsmentioning

confidence: 90%

Synthesis and anticoagulant activity of the quaternary ammonium chitosan sulfates

Fan

Zhang

et al. 2012

International Journal of Biological Macromolecules

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NMR and FT Raman characterisation of regioselectively sulfated chitosan regarding the distribution of sulfate groups and the degree of substitution

Cited by 62 publications

References 46 publications

Water soluble EDTA-linked chitosan as a zwitterionic flocculant for pH sensitive removal of Cu(ii) ion

Water soluble EDTA-linked chitosan as a zwitterionic flocculant for pH sensitive removal of Cu(ii) ion

Sulfated chitosan as tear substitute with no antimicrobial activity

Synthesis and anticoagulant activity of the quaternary ammonium chitosan sulfates

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