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Kinetics of swelling and drug release from PNIPAAm/alginate stimuli responsive hydrogels for controlled drug release

Cornelia A. Vasile 1Raluca P. Dumitriu Ana Maria Oprea 

1. Petru Poni Institute of Macromolecular Chemistry of the Romanian Academy, Aleea Grigore Ghica Voda 41A, Iasi, Romania


Environmentally responsive hydrogels are very attractive for applications in sustained and /or targeted drug delivery systems. As the release of drugs is related to the swelling behavior of hydrogels, the swelling kinetic studies become of great importance to appreciate the release kinetic from hydrogels matrices.

Hydrogels with high performance properties have been prepared from N-isopropyl amide (NIPAAm) and sodium alginate, crosslinked with N, N`-methylene- bis-(acrylamide) (MBAAm).

This study is focused on the investigation of swelling and drug release kinetics, completed by morphological studies.

The kinetic parameters of the swelling performed at different temperatures and pHs for hydrogels samples with different mixing ratios of the components and various crosslinking degrees have been evaluated and  showed  their dual responsive behavior (under temperature and pH changes). The results obtained by swelling kinetics investigation showed the decrease of the swelling rate constant with increasing temperature and increase with the alginate content in the samples.

The drug release kinetic study from the prepared hydrogel matrices was performed in twice-distilled water and ethanol for bioactive agents as vanillin and ketoprofen, respectively. An increase of alginate content results in a slower rate and smaller percentage of vanillin and ketoprofen released. The ketoprofen release behavior fitted with case II of transport and vanillin release behavior fitted with an anomalous transport of drugs.  The values of  k decreased by increasing  ethanol quantity in case of  75/25 NIPAAm/alginate hydrogels and decreased also by increasing content of alginate in hydrogels with various compositions.

Morphological studies performed by environmental scanning electron microscopy (ESEM) allowed us to observe the behavior of the hydrogel samples according to water content changes (relative humidity RH %) and to explain the behaviour both at swelling and release profiles.

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Related papers

Presentation: Poster at E-MRS Fall Meeting 2008, Symposium C, by Cornelia A. Vasile
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-12 21:04
Revised:   2009-06-07 00:48