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Semi-interpenetrating network (IPN) of sodium alginate (NaAlg) and N-isopropylacrylamide (NIPAAm) microspheres were prepared by water-in-oil (w/o) emulsification method. The microspheres were encapsulated with 5-fluorouracil (5-FU) and release patterns carried in 7.4 pH at temperatures of 25 and 37°C. The semi-IPN microspheres were characterized by Fourier transform infrared spectroscopy (FTIR). Differential scanning calorimetry (DSC) and scanning electron microscopic studies were done on the drug-loaded microspheres to confirm the polymorphism of 5-FU and surface morphology of microspheres. These results indicated the molecular level dispersion of 5-FU in the semi-IPN microspheres. Particle size and size distribution were studied by laser light diffraction technique. Microspheres exhibited release of 5-FU up to 12 h. The swelling studies were carried in 1.2 and 7.4 pH buffer media at 25 and 37°C. Drug release from NaAlg-NIPAAm semi-IPN microspheres at 25 and 37°C confirmed the thermosensitive nature by in vitro dissolution. The micro domains have released in a controlled manner due the presence of NIPAAm in the matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Methyl methacrylate (MMA), methoxy poly (ethylene glycol) monomaleate (MPEG), and acrylamidogly- colic acid (AGA) terpolymeric microgels (MGs) have been synthesized by free-radical surfactant-free emulsion poly- merization. MPEG was synthesized from maleic anhydride and methoxy poly(ethylene glycol). The MGs were cross- linked with ethylene glycol dimethacrylate, and the chemi- cal crosslinking was confirmed by Fourier transform infrared spectroscopy. 5-Fluorouracil (5-FU), a model anti- cancer drug, has been loaded into the MGs by in situ and adsorption methods. Empty as well as drug-loaded MGs were then characterized by transmission electron micros- copy (TEM), differential scanning calorimetry (DSC), and X- ray diffraction (XRD). DSC and XRD studies indicated a molecular level dispersion of the drug in PMMA MGs dur- ing in situ loading. TEM images showed the formation of spherical MGs. In vitro release of 5-FU from the crosslinked poly(MMA-co-AGA-co-MPEG) MGs were investigated at both pH 7.4 and 1.2 buffer medium that controlled release of the drug up to � 18 h. Both the encapsulation efficiency and the release patterns were dependent on the amount of crosslinking agent and the amount of drug loaded. V C 2008