Synthesis and Characterization of a Biocompatible Nanoplatform Based on Silica-Embedded SPIONs Functionalized with Polydopamine.

Superparamagnetic iron oxide nanoparticles (SPIONs) have gained increasing interest in nanomedicine, but most of those that have entered the clinical trials have been withdrawn due to toxicity concerns. Therefore, there is an urgent need to design low-risk and biocompatible SPION formulations. In this work, we present an original safe-by-design nanoplatform made of silica nanoparticles loaded with SPIONs and decorated with polydopamine (SPIONs@SiO2-PDA) and the study of its biocompatibility performance by an ad hoc thorough in vitro to in vivo nanotoxicological methodology. The results indicate that the SPIONs@SiO2-PDA have excellent colloidal stability in serum-supplemented culture media, even after long-term (24 h) exposure, showing no cytotoxic or genotoxic effects in vitro and ex vivo. Physiological responses, evaluated in vivo using Caenorhabditis elegans as the animal model, showed no impact on fertility and embryonic viability, induction of an oxidative stress response, and a mild impact on animal locomotion. These tests indicate that the synergistic combination of the silica matrix and PDA coating we developed effectively protects the SPIONs, providing enhanced colloidal stability and excellent biocompatibility.

Cubic Anisotropic Co- and Zn-Substituted Ferrite Nanoparticles as Multimodal Magnetic Agents.

The use of magnetic nanoparticles as theranostic agents for the detection and treatment of cancer diseases has been extensively analyzed in the last few years. In this work, cubic-shaped cobalt and zinc-doped iron oxide nanoparticles with edge lengths in the range from 28 to 94 nm are proposed as negative contrast agents for magnetic resonance imaging and to generate localized heat by magnetic hyperthermia, obtaining high values of transverse relaxation coefficients and specific adsorption rates. The applied magnetic fields presented suitable characteristics for the potential validation of the results into the clinical practice in all cases. Pure iron oxide and cobalt- and zinc-substituted ferrites have been structurally and magnetically characterized, observing magnetite as the predominant phase and weak ferrimagnetic behavior at room temperature, with saturation values even larger than those of bulk magnetite. The coercive force increased due to the incorporation of cobalt ions, while zinc substitution promotes a significant increase in saturation magnetization. After their transfer to aqueous solution, those particles showing the best properties were chosen for evaluation in in vitro cell models, exhibiting high critical cytotoxic concentrations and high internalization degrees in several cell lines. The magnetic behavior of the nanocubes after their successful cell internalization was analyzed, detecting negligible variations on their magnetic hysteresis loops and a significant decrease in the specific adsorption rate values.