Hydrogel nanocomposite based on starch and Co-doped zinc ferrite nanoparticles that shows magnetic field-responsive drug release changes

This paper describes the synthesis and characterization of a hydrogel nanocomposite based on starch and Co-doped zinc ferrite nanoparticles (Co0.50Zn0.50Fe2O4) that underwent drug release changes in response to an external magnetic field. The material was prepared using vinylated starch together with N',N'-dimethylacrylamide (DMAAm) and Co0.50Zn0.50Fe2O4 (CZ) via an ultrasound-assisted radical cross-linking/polymerization reaction. CZ was synthesized by an adapted sol-gel method that uses water as solvent, from which nanoparticles with an average crystallite size of 13 nm were obtained. The drug release profile of the hydrogels was obtained by fitting the experimental data to power law equation, using prednisolone as a model drug. In the hydrogel without CZ, the prednisolone release was driven by an anomalous transport, contributions of macromolecular relaxation and the Fickian diffusion. With addition of CZ, the drug release tended towards the Fickian diffusion. In such a case, the macromolecular relaxation is minimized and the Fickian mechanism begins to prevail. When the magnetic field was applied, the anomalous mechanism became more important, which makes the release more favorable. It was shown that, under magnetic field, 90% of initial prednisolone load is released at early times. On the other hand, the more densely cross-linked hydrogels showed irrelevant release changes in response to magnetic field, owing to their tighter polymer structure. Cytotoxicity research showed that both the hydrogels and CZ have great pharmacological potential and an appropriate level of security for use in the biological systems. (C) 2014 Published by Elsevier B.V.