Carboxymethyl chitosan (CMCS) was synthesized and blended with gelatin (GE) to prepare\nhydrogel microspheres by w/o emulsion cross-linking in the presence of glutaraldehyde (GA), which\nacted as a cross-linker. 5-Fluorouracil (5-FU) was encapsulated to investigate its controlled release (CR)\ncharacteristics in acidic (pH 1.2) and alkaline (pH 7.4) buffer media. The microspheres which formed\nwere spherical in nature, with smooth surfaces, as judged by the scanning electron microscopy\n(SEM). Fourier transform infrared spectroscopy (FTIR) confirmed the carboxymethylation of CS\nand the chemical stability of 5-FU in the formulations. Differential scanning calorimetry (DSC)\nand X-ray diffraction (XRD) confirmed the physical state and molecular level dispersion of 5-FU.\nEquilibrium swelling of microspheres was performed in water, in order to understand the water\nuptake properties. The in vitro release of 5-FU was extended up to 12 h in pH 7.4 phosphate\nbuffer, revealing an encapsulation efficiency of 72%. The effects of blend composition, the extent of\ncross-linking, and initial drug loading on the in vitro release properties, were investigated. When\nanalyzed through empirical equations, the release data suggested a non-Fickian transport mechanism.
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