Superparamagnetic MnFe2O4@Fe2O3 lipid-coated small nanoparticles: Synthesis, physicochemical characterization and biocompatibility assessment in drosophila melanogaster

Magnetic nanoparticles (MNPs), particularly manganese ferrite (MnFe₂O₄), have emerged as promising candidates for biomedical applications due to their tunable magnetic properties, biocompatibility, and functionalization potential. In this study, we synthesized superparamagnetic MnFe₂O₄@Fe₂O₃ core-shell nanoparticles (5.8 nm inorganic core, ∼10 nm lipid-coated) functionalized with oleic acid (OA) or soy lecithin (Lec) to enhance biocompatibility. To the best of our knowledge, this work is the first to combine this unique hybrid core-shell structure with lipid coatings and evaluate its safety in an animal model. To characterize the MNPs we provided structural, magnetic, and physical-chemistry studies using transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), dynamic light scattering (DLS), X-ray diffraction (XRD), magnetization hysteresis, Fourier transform infrared spectroscopy (FTIR) measurements. To assess acute and chronic nanotoxicity, fruit flies from parental and F₁ generations were fed a diet containing MNPs at concentrations of 0.0, 0.1, and 1.0 mg/mL, and were evaluated throughout all developmental stages. The findings revealed that the MNPs showed no signs of toxicity at any of the concentrations tested. We combined hybrid core-shell superparamagnetic nanoparticles with organic lipid-coated that exhibit unique physicochemical characteristics, confirming their low <i>in vivo</i> nanotoxicity in <i>Drosophila melanogaster</i> and supporting their potential as biocompatible, magnetically responsive and small-sized platforms for biomedical application such as drug delivery due to their biocompatibility, magnetic properties, and physicochemical stability.