Superparamagnetic iron oxide nanoparticles (SPIONs) are promising drug delivery carriers and hyperthermia agents for the treatment of cancer. However, to ensure their safety in vivo, SPIONs must be modified in order to prevent unwanted iron release. Thus, SPIONs were coated with silica layers of different morphologies: non-porous (@SiO2), mesoporous (@mSiO2) or with a combination of non-porous and mesoporous layers (@SiO2@mSiO2) deposited via a sol-gel method. The presence of SiO2 drastically changed the surface properties of the nanoparticles. The zeta potential changed from 19.6 ± 0.8 mV for SPIONs to -26.1 ± 0.1 mV for SPION@mSiO2. The Brunauer-Emmett-Teller (BET) surface area increased from 7.54 ± 0.02 m2/g for SPIONs to 101.3 ± 2.8 m2/g for SPION@mSiO2. All types of coatings significantly decreased iron release (at least 10 fold as compared to unmodified SPIONs). SPIONs and SPION@mSiO2 were tested in vitro in contact with human lung epithelial cells (A549 and BEAS-2B). Both nanoparticle types were cytocompatible, although some delay in proliferation was observed for BEAS-2B cells as compared to A549 cells, which was correlated with increased cell velocity and nanoparticles uptake.
Keywords: Atomic Force Microscopy; controlled drug release; drug delivery; iron release; lung cancer; nano-bio-characterization; nanoformualtions; nanoparticles; silica coating; superparamagnetic iron oxide nanoparticles (SPIONs).