Water affinity and permeability in membranes of alginate-Ca2+ containing poly(n-isopropylacrylamide)

Guilherme, Marcos R.; Toledo, Eduardo Aparecido; Rubira, Adley F.; Muniz, Edvani C.

doi:10.1016/s0376-7388(02)00382-4

Cited by 38 publications

(17 citation statements)

References 27 publications

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“…[15] Briefly, an aqueous solution was prepared by dissolving 35.3 mmol of NIPAAM and 1.35 mmol of APS in 45 ml of deionized water. The solution was then purged with nitrogen over a period of 30 min to induce oxygen expulsion.…”

Section: Synthesis Of Pnipaammentioning

confidence: 99%

“…[11][12][13] Several studies concerning alginate/PNIPAAM hydrogels have been reported. [7,[14][15][16][17][18][19] For example, Ju et al [7,18] studied the pH/temperature dependence of the swelling behavior of alginate/PNIPAAM hydrogels and Guilherme et al [15] demonstrated the water Summary: A series of semi-interpenetrating, polymer network (semi-IPN), hydrogel beads, composed of calcium alginate (Ca-alginate) and poly(N-isopropylacrylamide) (PNIPAAM), were prepared for a pH/temperature-sensitive drug delivery study. The equilibrium swelling showed the independent pH-and thermo-responsive nature of the developed materials.…”

Section: Introductionmentioning

confidence: 99%

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Drug Release of pH/Temperature‐Responsive Calcium Alginate/Poly(N‐isopropylacrylamide) Semi‐IPN Beads

Shi

Alves

Mano

2006

Macromolecular Bioscience

145

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A series of semi-interpenetrating, polymer network (semi-IPN), hydrogel beads, composed of calcium alginate (Ca-alginate) and poly(N-isopropylacrylamide) (PNIPAAM), were prepared for a pH/temperature-sensitive drug delivery study. The equilibrium swelling showed the independent pH- and thermo- responsive nature of the developed materials. At pH=2.1, the release amount of indomethacin incorporated into these beads was about 10% within 400 min, while this value approached to 95% at pH=7.4. The release rate of the drug was higher at 37 degrees C than that at 25 degrees C and increased slightly with increasing PNIPAAM content. These results suggest that the Ca-alginate/PNIPAAM beads have the potential to be used as an effective pH/temperature sustainable delivery system of bioactive agents. [GRAPHS: SEE TEXT] A summary of the temperature- and pH-dependence on the release of the drug over a period of 450 min. The effect of the temperature on the swelling of the beads is shown in the inset.

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Section: Synthesis Of Pnipaammentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Drug Release of pH/Temperature‐Responsive Calcium Alginate/Poly(N‐isopropylacrylamide) Semi‐IPN Beads

Shi

Alves

Mano

2006

Macromolecular Bioscience

145

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“…19 It is shown that different concentration of alginate in the feed mixture influences swelling properties of IPN hydrogels. Degree of PNIPAAm crosslinking impacts the ESR at lower temperatures.…”

Section: Swelling Behaviormentioning

confidence: 99%

“…3 There are a number of reports referring to linear alginate (sodium alginate) in combination with crosslinked PNIPAAm having structures of semi-IPNs, [15][16][17][18] as well as to IPN hydrogels containing crosslinked PNIPAAm and CA. [19][20][21][22][23] The reports on PNIPAAm/CA hydrogels do not show that in addition to mechanical properties, IPN hydrogels could also feature improved swelling behavior and better response to temperature changes than pure PNIPAAm hydrogel. The major part of the published studies characterizes the IPN hydrogels with respect to pure CA hydrogels.…”

Section: Introductionmentioning

confidence: 98%

Development and characterization of thermosensitive hydrogels based on poly(N‐isopropylacrylamide) and calcium alginate

Petruš̆̌̌̌ić

Lewandowski

Giraud

et al. 2011

J of Applied Polymer Sci

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This work refers to the synthesis and characterization of thermosensitive hydrogels based on interpenetrating polymer networks (IPNs) of poly(N-isopropylacrylamide) (PNIPAAm) and calcium alginate in the form of films. The influence of the crosslinking degree of PNIPAAm and alginate content on thermal, swelling, mechanical, and morphological properties of hydrogels is investigated in detail. Characterization of pure PNIPAAm hydrogels and IPN hydrogels was performed by FTIR, DSC, DMA, and SEM. In addition, the studies of equilibrium swelling behavior as well as swelling, deswelling, and reswelling kinetics are performed.The results obtained imply the benefits of synthesizing IPNs based on PNIPAAm and calcium alginate over pure PNIPAAm hydrogels. The presence of calcium alginate contributes to the improvement of mechanical properties, the deswelling rate of hydrogels, and the network porosity, without altering the thermosensitivity of PNIPAAm significantly.

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“…O desenvolvimento de hidrogéis para utilização como biomateriais 1,2 baseia-se em síntese de hidrogéis sensíveis à temperatura 3,4 e também em modificações de superfície de polímeros 5,6 . Devido à resposta a temperatura, por exemplo, contração/expansão, os hidrogéis termo-sensíveis são citados na literatura como "biomateriais inteligentes".…”

Section: Introductionunclassified

Resistência mecânica de hidrogéis termo-sensíveis constituídos de Alginato-Ca2+ / PNIPAAm, tipo Semi-IPN

et al. 2007

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Recebido em 25/9/06; aceito em 16/3/07; publicado na web em 29/8/07MECHANICALS RESISTANCE OF THERMOSENSITIVE HYDROGELS CONSISTING OF ALGINATE-Ca 2+ / PNIPAAm, TYPE SEMI-IPN. Thermosensitive hydrogels were synthesized using alginate-Ca 2+ in association with a thermosensitive polymer, such as PNIPAAm. The mechanical properties of the hydrogels were determined measuring the maximum tension of deformation. With the increase of the temperature by 25 to 40 ºC above the LCST the chains of PNIPAAm collapsed, dragging the alginate net and diminishing the size of the pores. The decrease in the size of the pores of the hydrogel was followed by an increase in the mechanicals resistance of the material.Keywords: hydrogels; alginates; PNIPAAm. INTRODUÇÃOO desenvolvimento de hidrogéis para utilização como biomateriais 1,2 baseia-se em síntese de hidrogéis sensíveis à temperatura 3,4 e também em modificações de superfície de polímeros 5,6 . Devido à resposta a temperatura, por exemplo, contração/expansão, os hidrogéis termo-sensíveis são citados na literatura como "biomateriais inteligentes". Para desenvolver "biomateriais inteligentes" utilizam-se, entre outras, as propriedades do poli (Nisopropil acrilamida), ou PNIPAAm. O PNIPAAm é um polímero que apresenta, em solução aquosa, diagrama de fases tipo LCST, isto é, apresenta "Lower Critical Solution Temperature" em cerca de 32-33 ºC [7][8][9][10][11][12][13] . No entanto, uma séria limitação para tais aplicações é o fato de que hidrogéis de PNIPAAm apresentam propriedades mecânicas muito pobres quando intumescidos 11 . Para contornar esta barreira tecnológica, procedimentos alternativos têm demonstrado ser eficientes para melhorar as propriedades mecânicas do hidrogel. Hidrogéis de PNIPAAm tipo semi-IPN têm sido preparados por polimerização do monômero NIPAAm em presença de agente de reticulação e de um polímero mais hidrofílico 11 . SemiIPNs contendo PNIPAAm exibem melhores propriedades mecâni-cas que o hidrogel contendo somente PNIPAAm e, em adição, a temperatura de LCST do PNIPAAm não é afetada 12 .Alginatos são extraídos de uma classe de algas marrons conhecidas como Phaeophyceae. As principais algas marinhas para produção comercial de alginato incluem Macrocystis pyrifera, Laminaria hyperborea, Laminaria digitata e Ascophyllum nodosum, que são encontradas mundialmente 13 . O alginato é um polissacarídeo autodegradável quando aquecido por tempo prolongado 13 , é formado por unidades de ácidos D-manurônico e L-glucurônico ligadas em 1-4, formando o ácido algínico. É muito solúvel em água e forma soluções viscosas com propriedades que dependem da massa molar, dos componentes e dos íons presentes. A viscosidade da solução diminui com o aumento da temperatura, formando gel estável em pH de 5,0 a 10,0.Para analisar a dependência do intumescimento, da tensão (de compressão), do módulo de elasticidade com o teor de PNIPAAm e com a temperatura foram realizados estudos envolvendo medidas de compressão dos hidrogéis de alginato com PNIPAAm tipo semi-IPN

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Water affinity and permeability in membranes of alginate-Ca2+ containing poly(n-isopropylacrylamide)

Cited by 38 publications

References 27 publications

Drug Release of pH/Temperature‐Responsive Calcium Alginate/Poly(N‐isopropylacrylamide) Semi‐IPN Beads

Drug Release of pH/Temperature‐Responsive Calcium Alginate/Poly(N‐isopropylacrylamide) Semi‐IPN Beads

Development and characterization of thermosensitive hydrogels based on poly(N‐isopropylacrylamide) and calcium alginate

Resistência mecânica de hidrogéis termo-sensíveis constituídos de Alginato-Ca2+ / PNIPAAm, tipo Semi-IPN

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