High-resolution solid-state carbon-13 NMR study of chitosan and its salts with acids: conformational characterization of polymorphs and helical structures as viewed from the conformation-dependent carbon-13 chemical shifts

Saito, Hajime; Tabeta, Ryoko; Ogawa, K.

doi:10.1021/ma00176a017

Cited by 208 publications

(112 citation statements)

References 6 publications

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“…It has been demonstrated that the conformation-dependent 13 C chemical shifts of the C-1 and C-4 carbon atoms of chitosan and its acid salts, which are next to the glycosidic linkage, varied appreciably (up to 8 ppm) with the two torsion angles at the glycosidic linkages, C-1-Ogly (q) and Ogly-C-4 (c), respectively. 21) Clearly, the chemical shifts of both C-1 and C-4 carbon atoms of the gentisic acid and aspirin salts were diŠerent from those of tendon chitosan. These NMR results indicate that, in both the gentisic acid and aspirin salts, the chitosan molecules had a similar conformation to each other, but diŠerent from that of tendon chitosan (the extended two-fold helix).…”

Section: Resultsmentioning

confidence: 95%

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Fourth 3D Structure of the Chitosan Molecule: Conformation of Chitosan in Its Salts with Medical Organic Acids Having a Phenyl Group

Kawahara

Yui

Oka

et al. 2003

Bioscience, Biotechnology, and Biochemistry

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Section: Resultsmentioning

confidence: 95%

“…Figure 3 shows 13 C CP-MAS NMR spectra of tendon chitosan and its salts of gentisic acid and aspirin; all sample specimens were the same as those served for the x-ray diŠraction measurements. According to Saito et al, 21) the 13 C-NMR signals of tendon chitosan are assigned as shown in Fig. 3 and Table 2.…”

Section: Resultsmentioning

confidence: 99%

Fourth 3D Structure of the Chitosan Molecule: Conformation of Chitosan in Its Salts with Medical Organic Acids Having a Phenyl Group

Kawahara

Yui

Oka

et al. 2003

Bioscience, Biotechnology, and Biochemistry

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“…The signals of C4, C5, C3, C6 are only slight changed by the formation of COOH, demonstrating that the modification mainly happened on the amino group of C2 as shown in Figure 3. C1 NMR signal of LCH is a singlet and the C2 signal of it also appears as one peak, suggesting that LCH presents 2-fold helical structure [14]. In contrast, the C1 of CH is split into a number of sharp peaks, and the C2 is split into a doublet with the separation of which is 1.64 ppm (see Table 1).…”

Section: Characterization Of Lch Spongesmentioning

confidence: 99%

Study on Chitosan-Lactate Sponges with Oriented Pores as Potential Wound Dressing

Lai¹,

Chen²,

Zhang³

2013

MSA

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The motive of this work was to provide an inexpensive potential wound dressing using chitosan lactate (LCH) which was synthesized by the grafting lactic acid onto the amino groups in chitosan (CH) without a catalyst. The XRD and 13 C NMR results demonstrated that the grafting by lactic acid took place at C2 site in CH, leading to the destruction of the regularity of the packing in the original CH chains and formation of the amorphous CH salts. The unique device was developed in our experiments which could yield an approximately vertical thermal gradient, forming the uniformly vertical pores in LCH sponges. TEM images revealed that both TBA and LCH concentration affected the micro-structure of the sponges, although they worked via different mechanisms. In the water suction experiments, the capillary coefficient Ks was introduced to evaluate the structure-function relationship. The positive or negative influence of LCH, TBA and porosity on Ks clearly stood out when their relationships were plotted graphically. The in vitro biocompatibility of LCH sponges was evaluated. The results obtained indicated that LCH sponges exhibited bio-safety at lower concentration (25%) during short time (1 day). However, highly concentrated extraction showed a serious toxic effect on both HSF and HaCaT cells. The release kinetics for hydrophilic and hydrophobic drugs with different formulation sponges was determined in in vitro release experiments. The contribution of the drug diffusion, matrix erosion and microstructure of porous materials must be taken into account on the release mechanism. The method and the structure described in present paper provided a starting point for the design and fabrication of a family of chitosan derivatives based porous materials with potentially broad applicability

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“…In both compounds one can select six non-equivalent carbon (C1-C6) and four non-equivalent oxygen atoms from different functional groups: -O-(O5) which belongs to glucose ring, -O-(O1, O4) which links the adjacent glucose rings, OH (O3) and CH 2 OH (O6). According to the experimental results, 13 C NMR signals 11,12 show six non-equivalent carbons of C1-C6 for both cellulose and chitosan polymers in Figure 2. For the XPS of the cellulose, 23 experimental CEBEs of O 1s consist of two different -O-and -OH peaks centered at 532.9 and 533.5 eV, respectively, and the C 1s is also due to two kinds of -O-CH-O-and -CH(OH) peaks at 288.1 and 286.7 eV.…”

Section: Resultsmentioning

confidence: 90%

Analysis of 13C NMR Chemical Shielding and XPS for Cellulose and Chitosan by DFT Calculations Using the Model Molecules

Danielache

Mizuno

Shimada

et al. 2005

Polym J

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ABSTRACT:13 C NMR chemical shielding and XPS of cellulose and chitosan were analyzed by deMon DFT calculations using the model dimers. The calculated 13 C chemical shifts of (-D-glucose, -D-glucose, and -D-glucosamine) and cellobiose with DZVP basis are in considerably good accordance with the experimental values in the average absolute deviations (AAD) of AE3:1 and 2.0 ppm, respectively. The calculated shifts of the dimer models for cellulose and chitosan also correspond well to the experimental ones of both solid biopolymers in the AAD of AE3:1 ppm. In order to simulate the valence XPS and to calculate core-electron binding energies (CEBE)s of cellulose and chitosan, we used the restricted diffuse ionization (rDI) and generalized transition-state (GTS) methods, respectively, due to Slater's transition-state (TS) concept. The simulated valence spectra of the dimer models showed good agreement with the experimental ones of cellulose and chitosan. We also estimated as 5.9 and 5.7 eV for WD (work function and the other energies) values of cellulose and chitosan, respectively from the differences between calculated CEBE values for the model molecules and experimental ones on the solid polymers. [DOI 10.1295/polymj.37.21] KEY WORDS 13 C NMR Chemical Shielding / X-ray Photoelectron Spectra / DFT Calculations / Saccharide / Amino-Sugar / It is well-known that cellulose is one of the most abundant natural polymers which has the biological functions of providing cells with mechanical strength and framework. One found cellulose many important applications in areas such as food, drug-delivery systems, and in textile and pulping-paper industries. The elucidation of the structural and dynamic properties of cellulose is, therefore, fundamental to understanding its role in plant cell walls and its functionality in applications. On the other hand, chitosan is especially known as a most powerful adsorbent of natural origin and widely used for the prevention of water pollution by highly toxic chlorinated aromatic compounds and metal ions.1 It is easily prepared from chitin by deacetylating its acetoamide groups with a strong alkaline solution. Chitosan is inexpensive, environmentally benign, harmless to humans, and a hugely obtainable biomass, and makes it very promising and attracting for use in many applications. As so far as we know, no one currently still demonstrates the fundamental studies on the electronic state of the two biopolymers (cellulose and chitosan) from both experimental and theoretical viewpoints.Studies of NMR and XPS properties in organic compounds contain a lot of valuable information concerning the nature of chemical bonds. The former studies of magnetic properties provide information about the roles of angular momentum of electrons in the chemical bonds. The latter XPS gives precise information on the electronic states involving the individual functional group of organic compounds. In our previous studies on 13 C NMR and XPS of organic compounds, 2-6 we performed the better assignments for 13 C NMR sign...

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High-resolution solid-state carbon-13 NMR study of chitosan and its salts with acids: conformational characterization of polymorphs and helical structures as viewed from the conformation-dependent carbon-13 chemical shifts

Cited by 208 publications

References 6 publications

Fourth 3D Structure of the Chitosan Molecule: Conformation of Chitosan in Its Salts with Medical Organic Acids Having a Phenyl Group

Fourth 3D Structure of the Chitosan Molecule: Conformation of Chitosan in Its Salts with Medical Organic Acids Having a Phenyl Group

Study on Chitosan-Lactate Sponges with Oriented Pores as Potential Wound Dressing

Analysis of 13C NMR Chemical Shielding and XPS for Cellulose and Chitosan by DFT Calculations Using the Model Molecules

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