Electrically induced swelling and methylene blue release behaviour of poly (N-isopropylacrylamide-co-acrylamido-2-methylpropyl sulphonic acid) hydrogels
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Hydrogels composed of poly (ethylene glycol) (PEG)/poly (N-isopropylacrylamide-co-acrylamido-2-methylpropyl sulphonic acid) exhibited electro-responsive behaviour. The swelling properties of hydrogels were influenced by the content of negatively charged ionic groups inside the network structure, cross-linking density, electric field intensity and electrolyte solution. The swelling ratio (SR) increased from 92.4 to 188.08, and normalized swelling ratio (NSR) increased from 2.88 to 3.62 depending on 2-acrylamido-2-methylpropane sulphonic acid (AMPS) concentration under electric field intensity 429 V/m. The swelling process of hydrogels in deionized water followed non-Fickian diffusion in the absence of electric field and Super Case II transport model in presence of electric field. The methylene blue (MB) was used as a model drug, and the influence of various factors like loading percent of MB, AMPS concentration in hydrogels, pH of the release medium and applied electric field was investigated on the release profiles of the MB. The release study showed that the interaction between hydrogels and MB, pH of the medium and electric field are the parameters that affect the releasing behaviour of methylene blue. The partition coefficient (Kd) of MB in hydrogels increased with increasing AMPS content in the hydrogels. The application of external electric field has increased the time response of swell and release of methylene blue through hydrogels.
KeywordsElectric field sensitive Hydrogels Diffusion Partition coefficient
The author (A.K. Saikia) sincerely thank Dr. Shipra Mittal Gupta, University School of Basic & Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, Delhi, for providing the UV spectrophotometer instrument facilities to complete this paper.
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