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

Abstract

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 in vivo nanotoxicity in Drosophila melanogaster 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.

Keywords: Biocompatibility; Drosophila melanogaster; Nanotoxicity; Oleic acid; Soy lecithin; Superparamagnetic nanoparticles.

Fig. 1

Physical characterization of the naked (MnFe₂O₄@Fe₂O₃), OA-coated (MnFe₂O₄@Fe₂O₃_OA), and lecithin-coated (MnFe₂O₄@Fe₂O₃_Lec) MNPs. A) XRD patterns of the powder samples and background. B-D) DLS analysis showing the experimental autocorrelation curves and bar graphs, the hydrodynamic diameter distribution by intensity, volume, and number for each sample. E-G) TEM micrographs and their corresponding nanoparticle size distribution histograms.

Fig. 2

Magnetic characterization of the naked (MnFe₂O₄@Fe₂O₃), OA-coated (MnFe₂O₄@Fe₂O₃_OA), and lecithin-coated (MnFe₂O₄@Fe₂O₃_Lec) MNPs. A-C) Magnetization (emu/g) vs. Applied Magnetic Field (kOe) at 290 K.

Fig. 3

A) Infrared transmission spectra (FTIR) of oleic acid (OA), naked MnFe₂O₄@Fe₂O₃ and MnFe₂O₄@Fe₂O₃_OA. B) FTIR peaks and assignment of oleic acid (OA), naked MnFe₂O₄@Fe₂O_3, and MnFe₂O₄@Fe₂O₃_OA.

Fig. 4

A-B) Negative geotaxis climbing assay: acute nanotoxicity studied in the parental generation (48 h of exposure) and chronic nanotoxicity studied by the F₁ generation. C-D) Percentage of survival (50 days) studied in the parental and F₁ generation. Survival percentage abnormality was not significantly found, ANOVA, p-value > 0.05. E) Dark-Light assay chronic nanotoxicity studied by the F1 generation. F) Larvae crawling speed for F₁ generation.