Synthesis, characterization and controlled drug release of thermosensitive IPN?PNIPAAm hydrogels

Synthesis, characterization and controlled drug release of thermosensitive IPNÒPNIPAAm hydrogels
Received 12 May 2003; accepted 10 October 2003. Available online 13 December 2003.
Xian-Zheng Zhang , Da-Qing Wu and Chih-Chang Chu ,
Volume 25, Issue 17 , August 2004
Department of Textiles and Apparel and Biomedical Engineering Program, Cornell University, Ithaca, NY 14853-4401, USA
A method was developed to prepare thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) hydrogels with an interpenetrating polymer network (IPN) structure for the purpose of improving its mechanical properties, response rate to temperature and sustained release of drugs. Although the differential scanning calorimetry data exhibited similarly lower critical solution temperature (LCST) between IPN- and non-IPNÒPNIPAAm hydrogels, an increase in the glass transition temperature (Tg) of the IPNs relative to the normal PNIPAAm hydrogel was observed. In addition, the mechanical properties of the IPNs were greatly improved when compared with the normal PNIPAAm hydrogel. The interior morphology of the IPNÒPNIPAAm hydrogels was revealed by scanning electron microscopy (SEM); the IPN hydrogels showed a fibrillar-like porous network structure that normal PNIPAAm did not have. Furthermore, by measuring the temperature dependence of the swelling ratio and deswelling kinetics, these IPN hydrogels also exhibited improved intelligent characteristics (e.g., controllable faster response rate) that depended on the composition ratio of the two network components. From the applications viewpoint, the effects of a shrinkingÒreswelling cycle around the LCST on the properties of the IPN hydrogels were examined to determine if these properties would be stable for potential applications. Bovine serum albumin was chosen as the model protein for examining its release from the IPNs at different temperatures. The release data suggested that an improved controlled release could be achieved by the IPNÒPNIPAAm hydrogels without losing their intelligent properties.
Author Keywords: Author Keywords: N-isopropylacrylamide; Interpenetrating polymer network; Hydrogel; Controlled drug release; Albumin

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