Biological Evaluation of FE₃O₄ Nanoparticles for Potential Applications in Dentistry

Objectives: To synthesize, characterize and evaluate by ISO10993-5 the cytotoxic and antibacterial effects of IONPs in the culture with human pulp cells (HPC) and human gingival fibroblasts (HGF) and Escherichia coli, Staphylococcus aureus and Enterococcus faecalis compared with commercial nanoparticles.
Methods: Fe₃O₄ NPs were synthesized using the chemical co-precipitation method. They were characterized by analysis with X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) and the magnetic properties were measured by a vibrating sample magnetometer (VSM) and compared commercial nanoparticles. The cells were cultured in DMEM medium. Both groups of Fe₃O₄ NPs were inoculated at different concentrations (0-2.5 mg/mL) for 24 hrs cell viability was determined by MTT assay; the antimicrobial effect was evaluated by microdilution in broth. The percentage, mean, standard deviation were calculated and data were subject to Shapiro-Wilk normality test, paired t-student test and ANOVA with post-hoc Tukey test, the significance was fixed to p<0.05.
Results: Fe₃O₄ NPs showed an average size of <50 nm. The HGF and HPC cells were not very sensitive after 24 hours of contact with IONPs, an increase in cell proliferation was observed. For IONPs, the minimum dose to induce toxicity was 0.62 mg/mL for HGF and 1.25 mg/mL for HPC. E. coli. was more resistant of bacterial tested their MIC was 0.62 mg/mL., for E. faecalis the MIC was 0.31 mg/mL for S. aureus of 0.31 mg/mL.
Conclusions: The iron oxide compounds show adequate cytocompatibility, antimicrobial effects and have potential application in dentistry.