Temperature-sensitive PVA/PNIPAAm semi-IPN hydrogels with enhanced responsive properties

Zhang, Jiantao; Bhat, Rahila; Jandt, Klaus D.

doi:10.1016/j.actbio.2008.06.012

Cited by 197 publications

(159 citation statements)

References 39 publications

(63 reference statements)

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“…The VPTT values of thermoresponsive hydrogels are generally determined by the equilibrium swelling ratio method [13,14]. Hydrogels (most in the form of discs or slabs) are weighed and allowed to reach their equilibrium swelling state at different temperatures.…”

Section: Introductionmentioning

confidence: 99%

Lower critical solution temperature versus volume phase transition temperature in thermoresponsive drug delivery systems

Constantin¹,

Cristea²,

Ascenzi³

et al. 2011

Express Polym. Lett.

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Abstract. One of the most subtle problem in the characterization of thermoresponsive polymers is the evaluation of the relationship between the lower critical solution temperature (LCST) of the linear polymer and the volume phase transition temperature (VPTT) of the corresponding hydrogel. Here, the LCST and the onset temperature of linear poly(N-isopropylacrylamide-co-N-hydroxymethyl acrylamide) has been determined under pseudo-physiological conditions by cloud point (CP) measurements and by microcalorimetric analysis. The LCSTs, as well as the onset temperatures, determined by the CP method, decrease with increasing the concentration of the polymer solution. On the contrary, microcalorimetric analyses give almost the same values for LCSTs and the onset temperatures regardless of polymer concentration. The VPTT of the hydrogel, determined by the blue dextran method, was found to be closely similar to the LCST of the concentrated polymer solution (10%, w/v), determined by the CP method. In fact, the hydrogel could be considered as a concentrated polymer solution whose concentration could be related to the amount of water retained by the hydrogel. Hydrogel microspheres have been also reported to release diclofenac, a drug model system, in a pulsating way at temperatures slightly below and above the VPTT.

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Section: Introductionmentioning

confidence: 99%

Lower critical solution temperature versus volume phase transition temperature in thermoresponsive drug delivery systems

Constantin¹,

Cristea²,

Ascenzi³

et al. 2011

Express Polym. Lett.

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“…Hydrogels made of PNIPAM exhibited unique hydrophilic/hydrophobic changes around the LCST of PNIPAM leading to the reversible swelling and shrinking behaviors, which can be used as effective trigger to modulate drug release. [21][22][23][24] However, the most serious disadvantage is that PNIPAM hydrogels are not biodegradable. There have been many successful efforts to prepare PNIPAM-based biodegradable hydrogels by using biodegradable crosslinkers containing dextran or polylactide (PLA) units.…”

Section: Introductionmentioning

confidence: 99%

Photo‐cross‐linked biodegradable thermo‐ and pH‐responsive hydrogels for controlled drug release

Zhao

Xiao

et al. 2011

J of Applied Polymer Sci

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A new strategy was developed to prepare thermo-and pH-sensitive hydrogels by the crosslinking of poly(N-isopropylacrylamide) with a biodegradable crosslinker derived from poly(L-glutamic acid). Hydrogels were fabricated by exposing aqueous solutions of precursor containing photoinitiator to UV light irradiation. The swelling behaviors of hydrogels at different temperatures, pHs, and ionic strengths were examined. The hydrogels shrank under acidic condition or at temperature above their collapse temperature and would swell in neutral or basic media or at lower temperature. These processes were reversible as the pH or temperature changed. All hydrogels exhibited no weight loss in the simulated gastric fluid but degraded rapidly in the simulated intestinal condition. Bovine serum albumin were used as a model protein drug and loaded into the hydrogels. The in vitro drug release experiment was carried out at different pH values and temperatures. The pH and temperature dependent release behaviors indicated the promising application of these materials as stimuli-responsive drug delivery vehicles.

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“…Alguns hidrogéis sintéticos não apresentam propriedades bioativas, fato que restringe sua aplicação na área tempo "t" o hidrogel era retirado da solução de intumescimento e cuidadosamente pesado. Os valores de Q foram obtidos por meio de razão da massa dos hidrogéis intumescidos e a massa dos hidrogéis secos [15] . As medidas foram realizadas em triplicata e as barras de erros correspondem ao desvio padrão (σ) (média ± σ, n = 3).…”

Section: Introductionunclassified

Investigação do processo de absorção de água de hidrogéis de polissacarídeo: efeito da carga iônica, presença de sais, concentrações de monômero e polissacarídeo

et al. 2012

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Neste trabalho foi reportada a caracterização de hidrogéis constituídos por metilcelulose (MC) e poliacrilamida (PAAm) preparados pelo processo de reticulação cruzada. As propriedades espectroscópicas e morfológicas foram investigadas por espectroscopia no infravermelho com transformada de Fourier e microscopia eletrônica de varredura, respectivamente. O efeito da carga iônica, presença de sais, concentrações de monômero AAm e polissacarídeo MC na absorção de água e nas propriedades cinéticas dos hidrogéis foi detalhadamente investigado. Os resultados indicaram que o decréscimo da concentração de MC ou aumento da concentração de AAm, carga iônica do contra-íon do sal de cloreto e a presença de fertilizante no meio externo de intumescimento provocaram diminuição significativa na absorção de água dos hidrogéis. O mecanismo de absorção de água dos hidrogéis de PAAm-MC em água seguiu o modelo de difusão Fickiana; já o mecanismo dos hidrogéis intumescidos em sais (cloreto ou fertilizante) seguiu o modelo de transporte anômalo. Pela alta e rápida absorção de água, as matrizes porosas e tridimensionais compostas por PAAm e MC podem em potencial ser aplicadas na agricultura como veículos carreadores.

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Temperature-sensitive PVA/PNIPAAm semi-IPN hydrogels with enhanced responsive properties

Cited by 197 publications

References 39 publications

Lower critical solution temperature versus volume phase transition temperature in thermoresponsive drug delivery systems

Lower critical solution temperature versus volume phase transition temperature in thermoresponsive drug delivery systems

Photo‐cross‐linked biodegradable thermo‐ and pH‐responsive hydrogels for controlled drug release

Investigação do processo de absorção de água de hidrogéis de polissacarídeo: efeito da carga iônica, presença de sais, concentrações de monômero e polissacarídeo

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