Degree of deacetylation of chitosan using conductometric titration and solid-state NMR

Raymond, Louise; Morin, Frederick G.; Marchessault, R. H.

doi:10.1016/0008-6215(93)84044-7

Cited by 254 publications

(177 citation statements)

References 11 publications

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“…§ Physical and Chemical Characterization of Chitosan Beads Diameter and density of the chitosan beads were determined by picnometry and bead porosity was determined using a gravimetric method (Gonçalves et al, 1997). The chitosan degree of deacetylation was obtained by potentiometric titration (Raymond et al, 1993). Using the infrared method, the chemical characterization of activated chitosan has been done with a Nicolet Protege 460 FTIR spectrometer.…”

Section: Stability Of the Immobilized Enzymementioning

confidence: 99%

Stabilization of penicillin G acylase by immobilization on glutaraldehyde-activated chitosan

Adriano

Filho

Silva

et al. 2005

Braz. J. Chem. Eng.

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-The objective of this work was to study enzyme immobilization on chitosan activated with glutaraldehyde, aiming to produce a cheap biocatalyst. Two different immobilization strategies were studied: one-point and multipoint covalent attachment to the solid matrix. The multipoint covalent attachment derivative had an 82% immobilization yield. It was 4.9-fold more stable than the free enzyme at 50°C and 4.5-fold more stable than soluble enzyme at pH 10.0. The one-point derivative had an 85% immobilization yield. It was 2.7-fold more stable than the free enzyme at 50°C and 3.8-fold more stable than soluble PGA at pH 10.0. Results indicated that chitosan can be loaded with PGA above 330 IU/g. Intraparticle diffusive effects, however, limited hydrolysis of penicillin G catalyzed by those derivatives at 37°C and 25°C. Operational stability assays were performed and the multipoint derivative exhibited a half-life of 40 hours.

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Section: Stability Of the Immobilized Enzymementioning

confidence: 99%

Stabilization of penicillin G acylase by immobilization on glutaraldehyde-activated chitosan

Adriano

Filho

Silva

et al. 2005

Braz. J. Chem. Eng.

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“…Finally, the last step consist in the alkaline deacetylation of β-chitin in a 40% (w/w) NaOH solution for 3 h at 80ºC, followed by water washes and drying at 40ºC for 5 days. Chitosan molecular weight (MW) and degree of acetylation (DA) were determined by viscosimetry and condutimetric titration, respectively 16 . DA calculated value was 9.05 % ± 0.…”

Section: Raw Materialsmentioning

confidence: 99%

In vivo Study of the Osteoregenerative Potential of Polymer Membranes Consisting of Chitosan and Carbon Nanotubes

et al. 2017

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Biomaterials with the hydroxyapatite and biopolymers such as chitosan derived of crustaceans are is an alternative for bone repair. Carbon nanotubes have been a focus of interest because they can ameliorate the biomechanical properties of biomaterials. The objective of this study was to evaluate these materials in the repair of cranial defects in rats. The animals were divided in groups: without implant (G1), implanted with the chitosan/carbon nanotube membrane (G2), and chitosan/nanotube membrane mineralized with hydroxyapatite (G3). The animals were sacrificed 5 weeks after surgery and the skulls were removed for analysis of the defect area. The results showed absence of chronic inflammatory and little bone neoformation in the defect area of all groups. In G2 and G3 there was lack of reabsorption of the biomaterial that were encapsulated by connective tissue. In conclusion, the biomaterials were biocompatible, but their specific physicochemical properties did not indicate a considerable osteoregenerative capacity.

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“…O grau de acetilação (GA) da quitosana foi determinado pelo método de titulação potenciométrica, segundo Raymond et al [16] . A amostra foi dissolvida em HCl 0,1 mol L …”

Section: Determinação Do Grau De Acetilaçãounclassified

Caracterização química e efeito cicatrizante de quitosana, com baixos valores de massa molar e grau de acetilação, em lesões cutâneas

et al. 2015

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ResumoInúmeras pesquisas buscam fármacos com propriedades cicatrizantes, capazes de reparar lesões cutâneas. O objetivo deste estudo foi caracterizar quimicamente uma quitosana e avaliar seus efeitos cicatrizantes em lesões cutâneas de ratos. A quitosana foi caracterizada quanto à viscosidade, massa molar, grau de acetilação, análise elementar, termogravimetria e espectroscopia na região do infravermelho. As propriedades cicatrizantes da quitosana foram avaliadas, para isso ratos adultos foram submetidos à excisão tecidual e tratados por 21 dias, sendo avaliados parâmetros macroscópicos, semanalmente, e microscópicos, ao final do experimento. A quitosana apresentou viscosidade de 5 mPa s, baixo grau de acetilação (GA=5,9%) e massa molar (132,0 kDa). Por análise elementar observou-se que a composição da quitosana se aproxima da fórmula C 6 H 11 O 4 N, suas principais bandas características foram observadas no espectro de infravermelho e a curva termogravimétrica mostrou que esta apresenta somente duas etapas de decomposição. Não houve diferença significativa na histologia, no 21º dia da lesão, entre os grupos controle e tratado, porém, macroscopicamente, a quitosana promoveu redução de 81,4% da largura das lesões, porcentagem significativamente superior à observada no grupo controle (71,2%), auxiliando a cura de lesões cutâneas, o que reforça seu potencial de aplicação médica. Palavras-chaves: grau de acetilação, análise termogravimétrica, propriedades cicatrizantes, quitosana. AbstractSeveral researches look for drugs with healing properties, capable to cure skin lesions. The objective of this study was to chemically characterize one chitosan and evaluate its healing effects in mice skin lesions. The chitosan was characterized in relation to the viscosity, molar mass, acetylation degree, elementary analysis, thermogravimetry and infrared spectroscopy. To evaluate the healing properties of chitosan mices were submitted to tissue excision and treated during 21 days. The macroscopic parameters were weekly evaluated and the microscopic parameters at the end of the experiment. Chitosan presented viscosity of 5 mPa s, low acetylation degree (GA= 5.9%) and molar mass of 132.0 kDa. By elemental analysis, we observed that the composition of chitosan is similar to the formula C 6 H 11 O 4 N, its main characteristic bands were observed in the infrared spectrum and the thermogravimetric curve showed two decomposition steps. There was no significant difference on the histology between the control and the treated group after the 21 st day of lesion. Macroscopically, chitosan caused the reduction of 81.4% of the lesions width, which is significantly superior to the observed reduction in the control group (71.2%), thus helping the cure of skin lesions. These results reinforces its potential use for medical application.Keywords: degree of acetylation, thermogravimetric analysis, healing properties, chitosan. IntroduçãoA pele reveste quase a totalidade da superfície corpórea e quando um dano tecidual compromete a continuidade des...

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Degree of deacetylation of chitosan using conductometric titration and solid-state NMR

Cited by 254 publications

References 11 publications

Stabilization of penicillin G acylase by immobilization on glutaraldehyde-activated chitosan

Stabilization of penicillin G acylase by immobilization on glutaraldehyde-activated chitosan

In vivo Study of the Osteoregenerative Potential of Polymer Membranes Consisting of Chitosan and Carbon Nanotubes

Caracterização química e efeito cicatrizante de quitosana, com baixos valores de massa molar e grau de acetilação, em lesões cutâneas

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