Iron oxide nanoparticles have been fabricated using the electric wire explosion (EWE) technique. The structure and magnetic properties of the nanoparticles have been analyzed before and after mechanical grinding in a ball mill for different time periods, focusing on potential bioapplications. The phase composition of the nanoparticles (70% Fe3O4, 30% Fe2O3) has remained unchanged despite the mechanical effects. The average nanoparticle size has not been affected either. The observation of the Verwey transition in the studied nanoparticles, along with the structural data, provides a better understanding of the physical properties of EWE ensembles of nanoparticles in different states. The analysis of the structure and magnetic properties reveals the development of a material with a high level of internal stress. This finding may be of interest for bioapplications due to its potential impact on the material performance.