To study the effects of radiofrequency magnetic fields on ferritin and the underlying mechanisms. Additionally, the aim of the study was to determine, whether the effects of such fields as described in a previous study (i.e. decrease in iron chelation following exposure, see Céspedes and Ueno 2009) are due to power dissipation of the ferrihydrite nanoparticles under exposure to the radiofrequency field.
The iron cage protein ferritin is an obvious candidate to study the effects of radiofrequency magnetic fields at the molecular scale, because it has the highest net magnetic moment of all proteins and plays an essential biological role, being present in organisms from bacteria to humans. Ferritin oxidizes the harmful Fe2+ ions and stores them in the cavity, forming a superparamagnetic ferrihydrite nanoparticle with up to 4,500 iron ions. Apoferritin solutions (protein without inner ferrihydrite nanoparticle) were also investigated.
|Exposure duration||continuous for 7 h|
|magnetic flux density||30 µT||maximum||calculated||-||-|
The data showed that exposure to a radiofrequency magnetic field affected the ability of native ferritin to uptake iron. However, the radiofrequency magnetic field had no effect on ferritin without inner superparamagnetic nanoparticle (i.e. apoferritin).
The superparamagnetic nanoparticles inside of ferritin increase their internal energy when exposed to radiofrequency magnetic fields due to the lag between magnetization and applied field. The energy is dissipated to the surrounding "protein cage", altering the molecular dynamics and functioning of the protein. This leads to an increased population of low energy vibrational states under a magnetic field of 30 µT at 1 MHz (as measured via Raman spectroscopy). After 2 h of exposure, the proteins have a reduced iron intake rate of about 20%.
In conclusion, the data open a new path for the study of non-thermal bioeffects of radiofrequency magnetic fields at the molecular scale. The authors hypothesize that the effect of the radiofrequency magnetic field on ferritin will depend not only on the applied field but also on the magnetic properties of the ferrihydrite nanoparticle inside ferritin.