Methyl methacrylate (MMA), methoxy poly (ethylene glycol) monomaleate (MPEG), and acrylamidoglycolic acid (AGA) terpolymeric microgels (MGs) have been synthesized by free-radical surfactant-free emulsion polymerization. MPEG was synthesized from maleic anhydride and methoxy poly(ethylene glycol). The MGs were crosslinked with ethylene glycol dimethacrylate, and the chemical crosslinking was confirmed by Fourier transform infrared spectroscopy. 5-Fluorouracil (5-FU), a model anticancer 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 microscopy (TEM), differential scanning calorimetry (DSC), and Xray diffraction (XRD). DSC and XRD studies indicated a molecular level dispersion of the drug in PMMA MGs during 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.
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 378C. 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 378C. Drug release from NaAlg-NIPAAm semi-IPN microspheres at 25 and 378C 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.
Blend microspheres of chitosan (CS) and guar gum (GG) have been prepared using the water-in-oil (w/o) emulsion method. Cefadroxil was loaded into the microspheres and crosslinked with glutaraldehyde, leading to the formation of a semi-interpenetrating polymer network (IPN) structure. The microspheres have been characterized by scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. Scanning electron micrographs showed the formation of non-uniform microspheres with the rough surface. X-ray diffraction and differential scanning calorimetry studies of the plain and the drug-loaded microspheres indicated that drug is dispersed at the molecular level in the semi-IPN matrix. In vitro dissolution experiments performed in pH 7.4 buffer medium indicated a sustained and controlled release of cefadroxil from semi-IPN microspheres up to 10 h. The amount of drug loaded into microspheres, CS-GG composition of the blend and the amount of cross-linking agent used have shown dependencies on the release of cefadroxil from the semi-IPN microspheres.
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