Influence of the composition and preparation method on the morphology and swelling behavior of alginate–chitosan hydrogels

Abreu, Flávia Oliveira Monteiro da Silva; Bianchini, Carla; Forte, Maria M.C.; Kist, Tarso B. Ledur

doi:10.1016/j.carbpol.2008.02.017

Cited by 69 publications

(50 citation statements)

References 27 publications

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“…These conditions were chosen due to good particle stability and properties reported previously [8,9], where hydrogels presented higher yield and lower swelling degree. In a previous study, it was seen that CHI based microspheres prepared at aqueous medium showed low encapsulation efficiency of hydrophilic drugs (unpublished results).…”

Section: Resultsmentioning

confidence: 99%

“…Also ALG-CHI microspheres were produced in aqueous medium, as described in earlier work [8], for comparison of properties. Polymer complexes were prepared using appropriate proportions, in order to obtain hydrogels with polymer ratio ALG:CHI = 35:65, condition previously optimized in previous articles [8,9]. The model drugs were added using a mass ratio Polymer:Drug of 5:1, condition optimized prior the design.…”

Section: Microspheres Preparationmentioning

confidence: 99%

“…Ionic and covalent crosslinkers can be added to the ALG-CHI system for improving the properties. Calcium chloride is frequently used as an ionic crosslinker in ALG-CHI systems [7][8][9]11] causing a reduction in the hydrogel porosity [17]. Among the covalent crosslinkers, there are some reports for chitosan nanoparticles crosslinked with glutaraldeyde [13,18] and genipin [19,20].…”

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confidence: 99%

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Effect of the preparation method on the drug loading of alginate-chitosan microspheres

Abreu¹,

Forte²,

Kist³

et al. 2010

Express Polym. Lett.

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Alginate-chitosan (ALG-CHI) microspheres obtained by polyelectrolyte complexation are pH-sensitive, biocompatible and adhesive, and are excellent candidates for the delivery of drugs, proteins and peptides in the human body. A wide variety of methods for the production of these polymeric complexes has been provided. The water-in-oil emulsion is a complex production method, but generally enhances the control of particle size and particle size distribution of the microspheres, extremely necessary for obtaining repeatable controlled release behavior. In this work, a novel and facile water-in-oil emulsion method for the ALG-CHI polyelectrolyte complexes is discussed. The method proposed produced ALG-CHI microspheres with improved morphology and enhanced drug loading in comparison with the aqueous medium method. The drug loading in the water-in-oil emulsion was over 30% higher than in the aqueous medium, an indication that the new method proposed the common drug leaching during the microspheres’ preparation is avoided, being an interesting alternative to encapsulate drugs of hydrophilic nature

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Section: Resultsmentioning

confidence: 99%

Section: Microspheres Preparationmentioning

confidence: 99%

mentioning

confidence: 99%

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Effect of the preparation method on the drug loading of alginate-chitosan microspheres

Abreu¹,

Forte²,

Kist³

et al. 2010

Express Polym. Lett.

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“…A viscosidade e a massa molar do polissacarídeo foram determinadas medindo-se o tempo de escoamento, em quintuplicata, de soluções poliméricas de várias concentrações em ácido acético 2% v/v em um viscosímetro de Otswald em banho termostático a 25 °C, conforme metodologia descrita em trabalho anterior [13] . A viscosidade específica e a viscosidade específica reduzida dos polímeros foram determinadas segundo as Equações 2 e 3:…”

Section: Caracterização Da Quitosanaunclassified

Propriedades e Características da Quitosana Obtida a Partir do Exoesqueleto de Caranguejo-Uçá Utilizando Radiação de Micro-Ondas

Abreu¹,

Cavalcante²,

Doudement³

et al. 2013

Polímeros

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Resumo: Neste trabalho, obteve-se quitosana a partir do exoesqueleto de Ucides cordatus cordatus, comumente denominado caranguejo-uçá, em um processo no qual a conversão da quitina em quitosana foi feita via reação convencional (QV) e também usando radiação de microondas (QP). Caracterizaram-se as quitosanas produzidas em função do grau de desacetilação (GD), viscosidade intrínseca (η) e massa molar viscosimétrica média (Mz), avaliando-se as propriedades em comparação com uma amostra de quitosana de caranguejo comercial (QC). A quitosana produzida por radiação de microondas apresentou grau de desacetilação maior do que a produzida via reação convencional e a quitosana comercial, com valores obtidos por titulação de 77%, 65% e 71% para QP, QV e QC, respectivamente. No teste de solubilidade, a amostra QP dissolveu mais facilmente em solução de ácido acético diluído do que a QC, enquanto que a amostra QV não apresentou boa solubilidade em solução de ácido acético 2%, devido ao seu baixo grau de desacetilação. A massa molar viscosimétrica das amostras QP e QC foi 412.600 g/mol e 336.100 g/mol, respectivamente, situando-se dentro dos padrões reportados na literatura. Em suma, pode-se afirmar que a conversão de quitina em quitosana por radiação com microondas é um método vantajoso, pois houve redução considerável de consumo de energia e de tempo em relação ao processo convencional, sendo que a amostra QP mostrou propriedades superiores à amostra QV, e propriedades equivalentes à amostra comercial QC. Além disso, o método empregado pode ser ajustado para produção de quitosana em escala industrial. Palavras-chave: Quitosana, Ucides cordatus cordatus, caranguejo, radiação de micro-ondas, grau de desacetilação. Development of New Method to Obtain Chitosan from the Exoskeleton of Crabs Using Microwave RadiationAbstract: In this work, chitosan was obtained from crab-uçá exoskeleton (Ucides cordatus cordatus), where conversion into chitosan was made with two techniques, namely conventional heating and using microwave radiation. The product obtained by radiation (QP) and conventional process (QV) were characterized and compared to a chitosan commercial sample (QC) regarding to the deacetylation degree (GD), viscosity average molar mass (Mz) and related properties. QP presented higher GD than QV and QC samples, with values of 77%, 65% and 71%, respectively. The solubility test showed that QP dissolved more easily in diluted acetic acid than QC, while QV did not dissolve in acid aqueous solution due to the low GD. QP also showed higher Mz than QC, with values of 412.600 g/mol and 336.100 g/mol, respectively. These properties agree with those reported in the literature. Therefore, the synthesis of chitosan from chitin using microwave reaction proved to be successful, since it is easier, faster and less expensive due to the time and energy optimization in comparison to the conventional process. The chitosan sample obtained displayed even better properties than a commercial sample. In addition, this process can be adjusted for pro...

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“…The point of zero charge (pH PZC ) of the adsorbent was determined by the solid addition method as described by Ai et al (2011). A digital pH meter (Marconi, Piracicaba, Brazil) was employed for the pH measurements.…”

Section: Determination Of the Point Of Zero Charge (Ph Pzc ) Of The Amentioning

confidence: 99%

Clarification of Aqueous Stevia Extract Using Alginate Beads — Evaluation by Factorial Design Methodology

Arakawa

Mahl

Oliveira

et al. 2012

Adsorption Science & Technology

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Stevia is used as a sweetener due to its low calorific value and its taste, which is very similar to that of sucrose. Stevia extract is dark in colour and needs to be clarified for better acceptance by consumers. The adsorption processes widely used in clarification do not use organic solvents. Alginate beads have been used as the adsorbent material in the present work. Experiments were carried out in batch mode in which the aqueous stevia extract was mixed with the alginate beads prepared previously by ionotropic gelation. A factorial design was used to study the process of clarification, in which colour removal and the percentage of stevioside adsorbed were evaluated. The studied factors were temperature, pH of the aqueous stevia extract and adsorption time. The results showed that alginate beads are capable of adsorbing both the steviosides and the pigments that give colour to the extract. The experimental design showed that only the pH and contact time were important variables in determining the percentage clarification, in contrast to the other responses which were not affected by the various factors studied. An equation describing the percentage clarification as a function of pH and time is proposed.

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Influence of the composition and preparation method on the morphology and swelling behavior of alginate–chitosan hydrogels

Cited by 69 publications

References 27 publications

Effect of the preparation method on the drug loading of alginate-chitosan microspheres

Effect of the preparation method on the drug loading of alginate-chitosan microspheres

Propriedades e Características da Quitosana Obtida a Partir do Exoesqueleto de Caranguejo-Uçá Utilizando Radiação de Micro-Ondas

Clarification of Aqueous Stevia Extract Using Alginate Beads — Evaluation by Factorial Design Methodology

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