Determination of the degree of deacetylation of chitin and chitosan by X-ray powder diffraction

Zhang, Yongqin; Xue, Changhu; Xue, Yong; Gao, Ruichang; Zhang, Xiuli

doi:10.1016/j.carres.2005.05.005

Cited by 374 publications

(214 citation statements)

References 16 publications

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“…After regeneration, the characteristic diffraction peak of cellulose II was detected at 20.7° (Freire et al 2011). The pure chitosan raw material shows diffraction peaks at 11.9°, 19.7°a nd 29.1°that can be assigned to (020), (110) and (130), respectively (Zhang et al 2005). The diffraction peaks at 11.9°(020) and 19.7°(110) represent the amorphous and the crystalline regions of chitosan (Yang et al 2012).…”

Section: Analysis Of Nanocomposites By Xrdmentioning

confidence: 99%

Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions

et al. 2016

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Novel cellulose-chitosan nanocomposite particles with spherical shape were successfully prepared via mixing of aqueous biopolymer solutions in three different ways. Macroparticles with diameters in the millimeter range were produced by dripping cellulose dissolved in cold LiOH/urea into acidic chitosan solutions, inducing instant co-regeneration of the biopolymers. Two types of microspheres, chemically crosslinked and non-crosslinked, were prepared by first mixing cellulose and chitosan solutions obtained from freeze thawing in LiOH/KOH/urea. Thereafter epichlorohydrin was applied as crosslinking agent for one of the samples, followed by water-inoil (W/O) emulsification, heat induced sol-gel transition, solvent exchange, washing and freeze-drying. Characterization by X-ray photoelectron spectroscopy, total elemental analysis, and Fourier transform infrared spectroscopy confirmed the prepared particles as being true cellulose-chitosan nanocomposites with different distribution of chitosan from the surface to the core of the particles depending on the preparation method. Field emission scanning electron microscopy and laser diffraction was performed to study the morphology and size distribution of the prepared particles. The morphology was found to vary due to different preparation routes, revealing a core shell structure for macroparticles prepared by dripping, and homogenous nanoporous structure for the microspheres. The non-crosslinked microparticles exhibited a somewhat denser structure than the crosslinked ones, which indicated that crosslinking restricts packing of the chains before and under regeneration. From the obtained volume-weighted size distributions it was found that the crosslinked microspheres had the highest median diameter. The results demonstrate that not only the mixing ratio and distribution of the two biopolymers, but also the morphology and nanocomposite particle diameters are tunable by choosing between the different routes of preparation.

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Section: Analysis Of Nanocomposites By Xrdmentioning

confidence: 99%

Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions

et al. 2016

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“…where I1-10 is the maximum intensity of the [1][2][3][4][5][6][7][8][9][10] mixed plane and Iam is the intensity of the amorphous diffraction at 16° [23]. d-Spacing was determined using Bragg's law, which states that…”

Section: X-ray Diffraction (Xrd)mentioning

confidence: 99%

Effect of purification method of β-chitin from squid pen on the properties of β-chitin nanofibers

Suenaga

Nikaido

Totani

et al. 2016

International Journal of Biological Macromolecules

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“…O comportamento químico de polímeros como quitina e quitosana dependem consideravelmente do GD [14] e a análise da atuação de enzimas e dos produtos formados são dependentes das características dos substratos.…”

Section: Caracterização Do Substrato Quitina Coloidalunclassified

Elucidação parcial da estrutura de aminoglucanooligossacarídeos (AGO's) produzidos enzimaticamente

et al. 2009

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e exo-quitinases. As endo-quitinases clivam de maneira randômica liberando oligômeros como quitotetraose, quitotriose e diacetilquitobiose. Exo-quitinases liberam progressivamente diacetilquitobiose da extremidade não redutora do polímero de quitina. Este último tipo de atividade quitinolítica foi também denominado de quitobiosidase. N-acetilglicosaminidases liberam monômeros de GlcNAc dos oligômeros resultantes da ação de endo e exoquitinases [3] .A hidrólise enzimática de polímeros por preparações comerciais e multienzimáticas para a produção de oligômeros têm sido relatadas por vários pesquisadores. A quitosana, polímero proveniente da desacetilação da quitina, foi hidro- IntroduçãoA quitina é um polímero de N-acetilglicosamina com ligações β-1,4 encontrada principalmente em carapaças de insetos, parede celular de fungos e crustáceos. É um biopolímero abundante e está geralmente ligado a outros polissacarídeos e proteínas. Refere-se a uma estrutura cristalina altamente ordenada e insolúvel em água [1] .As quitinases (E.C.3.2.1.14), denominadas também de poli [1,4-(N-acetil-β-D-glicosaminide)] glicanohidrolase, catalisam a hidrólise randômica de ligações glicosídicas β-1,4 de N-acetil-β-D-glicosamina (GlcNAc) em quitinas e quitodextrinas [2] . São classificadas como endo-quitinases Resumo: O presente trabalho visou a aplicação da enzima quitinolítica purificada da linhagem Cellulosimicrobium cellulans 191 e da preparação comercial de papaína na hidrólise da quitina coloidal. A quitina coloidal foi caracterizada quanto ao grau de desacetilação e apresentou GD de 14% por espectroscopia na região do infravermelho. A quitinase purificada hidrolisou a quitina coloidal liberando di-N-acetilquitobiose, enquanto que a preparação comercial de papaína atuando sobre o mesmo substrato formou di-N-acetilquitobiose e tri-N-acetilquitotriose. A estrutura química dos aminoglucanooligossacarídeos foi elucidada por espectrometria de massa. Palavras-chave: Quitinase, papaína, aminoglucanooligossacarídeos, quitina coloidal, espectrometria de massas. Partial Elucidation of the Chemical Structure of Aminoglucanoligosaccharides (AGO's) Produced EnzymaticallyAbstract: The aim of this work was the application of purified chitinolytic enzyme from Cellulosimicrobium cellulans 191 and the commercial papain in the hydrolysis of colloidal chitin. The latter was characterized with regard to the degree deacetylation (GD), with a GD of 14% being obtained using infrared spectroscopy. The purified chitinase hydrolysed the colloidal chitin and formed di-N-acetylchitobiose, while the commercial papain acting on the same substrate formed di-N-acetylchitobiose and tri-N-acetylchitotriose. The aminoglucanoligosaccharides chemical structure was elucidated by mass spectrometry.

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Determination of the degree of deacetylation of chitin and chitosan by X-ray powder diffraction

Cited by 374 publications

References 16 publications

Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions

Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions

Effect of purification method of β-chitin from squid pen on the properties of β-chitin nanofibers

Elucidação parcial da estrutura de aminoglucanooligossacarídeos (AGO's) produzidos enzimaticamente

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