Magnetic properties and application of biomineral particles produced by bacterial culture

Ferrihydrite nanoparticles (2–5 nm in size) produced by bacteria culture in the course of biomineralization of iron salt solutions from a natural medium exhibit unique magnetic properties: they are characterized by both the antiferromagnetic order inherent in a bulk ferrihydrite and the spontaneous magnetic moment due to the decompensation of spins in sublattices of a nanoparticle. The magnetic susceptibility enhanced by the superantiferromagnetism effect and the magnetic moment independent of the magnetic field provide the possibility of magnetically controlling these natural objects. This has opened up the possibilities for their use in nanomedicine and bioengineering. The results obtained from measurements of the magnetic properties of the bacterial ferrihydrite in its two main crystalline modifications are reported. This has made it possible to determine numerical values of the magnetic parameters of real biomineral nanoparticles.