Magnetic microgels for drug targeting applications: Physical–chemical properties and cytotoxicity evaluation

• Densely packed spherical clusters of magnetic nanoparticles were obtained.
• High magnetization microgels with superparamagnetic behavior are reported.
• The facile and reproducible synthesis procedure applied is easy to be up-scaled.
• The toxicity tests show that magnetic microgels are not cytotoxic.
• We show that mitoxantrone loaded microgels induce death of Jurkat cells.

Magnetoresponsive microgels with high saturation magnetization values have been obtained by a strategy based on the miniemulsion method using high colloidal stability organic carrier ferrofluid as primary material. Hydrophobic nanoparticles Fe3O4/oleic acid are densely packed into well-defined spherical nanoparticle clusters coated with polymers with sizes in the range 40–350 nm. Physical–chemical characteristics of magnetic microgels were investigated by TEM, SAXS, XPS and VSM measurements with the focus on the structure–properties relationship. The impact of magnetic microgels loaded with anticancer drug mitoxantrone (MTO) on the non-adherent human T cell leukemia line Jurkat was investigated in multiparameter flow cytometry. We showed that both MTO and microgel-loaded MTO penetrate into cells and both induce apoptosis and later secondary necrosis in a time- and dose dependent manner. In contrast, microgels without MTO are not cytotoxic in the corresponding concentrations. Our results show that MTO-loaded microgels are promising structures for application in magnetic drug targeting.