Radiofrequency Stimuli Applied to Suspensions Containing Biogenic Magnetite Nanocrystals: Absorbed Energy Conversion

Abstract

Water-based suspensions of magnetotactic bacteria (MTB) containing magnetite (Fe3O4) nanocrystals in the form of magnetosomes (MS) chained inside the bacteria cells have been exposed to radiofrequency fields with the aim of observing how the electromagnetic energy is converted and expressed as thermal or non-thermal effects. A wide frequency band was tested, (0.1-2.9) GHz, by applying continuous wave stimuli. Significant field strength components were provided and characterized, by using a GTEM cell and adequate expo-dosimetric instruments. The heating rates of the suspensions were measured. Because the recorded values were very low, non-thermal expression of energetic conversion was further investigated by scanning-transmission electron microscopy methods, by various spectroscopic means and by electrical conductivity determinations. Clear non-thermal effects were revealed, which need further research.