Novel composite poly(N-isopropylacrylamide) (PNIPAAm) hydrogels, containing poly(N-isopropylacrylamide)-block-poly(methyl methacrylate) (PNIPAAm-b-PMMA) micelles for sustained drug delivery were prepared and characterized. Various amounts of thermal sensitive PNIPAAm-b-PMMA micelles were incorporated physically into thermosensitive PNIPAAm bulk hydrogel to form composite PNIPAAm hydrogels. The resultant composite hydrogels were characterized by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) for morphological and thermal properties, respectively. The temperature dependence of swelling ratio and response kinetics upon heating or cooling were also investigated to understand the smart properties, that is, temperature-sensitive properties of the composite PNIPAAm hydrogels. These composite PNIPAAm hydrogels exhibited a faster shrinking kinetics than the one of pure PNIPAAm hydrogels. In addition, prednisone acetate, used as model drug, was loaded into the micelles incorporated to the composite PNIPAAm hydrogels. The controlled release behavior of the novel composite PNIPAAm hydrogels at different temperatures (22 and 37 degrees C) was examined.
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