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


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-IPN-PNIPAAm 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 IPN-PNIPAAm 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 shrinking-reswelling 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 IPN-PNIPAAm hydrogels without losing their intelligent properties.


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  • Authors+Show Affiliations


    Department of Textiles and Apparel and Biomedical Engineering Program, Cornell University, Ithaca, NY 14853-4401, USA.



    Biomaterials 25:17 2004 Aug pg 3793-805


    Acrylic Resins
    Biocompatible Materials
    Compressive Strength
    Delayed-Action Preparations
    Drug Delivery Systems
    Materials Testing
    Molecular Conformation
    Sensitivity and Specificity
    Serum Albumin, Bovine
    Surface Properties
    Tensile Strength
    Transition Temperature

    Pub Type(s)

    Evaluation Studies
    Journal Article
    Research Support, Non-U.S. Gov't



    PubMed ID