Controlling the Burst E ect of a Drug by Introducing Starch in the Structure of Magnetic Polyurethane Microspheres Containing Superparamagnetic Iron Oxide Nanoparticles

The aim of this research is to prepare superparamagnetic polyurethane microspheres using SPIONs. Theophylline was used as a drug and the various stoichiometric ratios of isocyanate/polyol were studied to assess their application as a targeting delivery system. Magnetic polyurethane microspheres containing superparamagnetic iron oxide nanoparticles loaded with theophylline were prepared by the water in oil in water emulsion technique. The ratio of hexamethylenediisocyanate and polyol ("-polycaprolactone and starch) was modi ed and the release of theophylline was determined for a period of 20 days. These microspheres were characterized by TEM, SEM, FTIR and magnetometry. The microscopy images show the morphological shape of the superparamagnetic microspheres with an average size of 5 m. The FTIR and the magnetometry confirmed the presence of superparamagnetic nanoparticles in the microspheres. The release of theophylline was studied and dosed by UV spectrophotometer. With the use of PCL with a low molecular weight or in the presence of starch in the structure of polyurethane, the burst effect of drug is decreased. Finally, a SEM study showed an important degradation of the microspheres after the release process. The use of starch as a polyol caused significant improvement in burst effect of the superparamagnetic polyurethane microspheres.