Antibacterial activity of Fe3O4 nanoparticles isolated and associated with electromagnetic fields on resistant Escherichia coli
Magnetic nanoparticles, resistant bacteria, magnetism
Due to the increase in bacterial resistance in recent years and the encouragement of WHO to develop innovative antimicrobial therapies, many studies have evaluated the possible antimicrobial effects of magnetic fields and their possibility of application, due to the fact that it is a non-pharmacological therapy and, therefore, exempt from the molecular effects of the resistance phenomenon. At the same time, magnetic nanoparticles with superparamagnetic properties, especially magnetite (Fe3O4), despite being widely explored as a site-specific drug delivery system associated with an external magnetic field, have other interesting properties that are poorly studied in relation to micro- organisms. In this sense, the present work evaluated the intrinsic antimicrobial properties of Fe3O4 nanoparticles associated or not with an external electromagnetic field (70 mT, 10 Hz). The tests on kanamycin-resistant Escherichia coli DH5α revealed bacteriostatic effects with significant growth decrease, important morphological changes in the cell wall and an increase in the zeta potential of the bacterial suspension, when exposed for 24 hours. These results reveal an important antimicrobial potential, both for Fe3O4 alone, and in combination with the magnetic field. Additionally, the Fe3O4 nanoparticles isolated demonstrated an additive inhibitory effect when combined with antibiotics, making it possible to decrease the necessary dose of the drug to obtain the same degree of bacterial inhibition and this points to a second option of use, as an adjunct to antibiotic therapy.