Abstract:

 Oriented chains of magnetite (Fe3O4) nanoparticles, similar to the magnetosome chains in magnetotactic bacteria (MTB),
have been synthesized by using akaganeite  (β-FeOOH) and  ferrous  ions as  iron species  through a biomimetic method without
protein or biomolecule. A detailed study by means of XRD, Micro-Raman spectrometer, TEM, SEM and HRTEM shows that the
oriented chain  is self-assembled by  roughly cuboidal magnetite crystals, and  these cuboidal nanoparticles are connected,  face
to  face, with  {100} or  {111}  facets. Based on  the  intrinsic dipolar structure, a magnetic dipole-dipole  interaction mechanism  is
proposed for formation of magnetite chains. Our results suggest that in magnetotactic bacteria, except for the biologic factors, the
dipolar  interaction among magnetosomes may be a potential candidate  for  the organization of magnetosomes  into  the chains.  It
appears that biological and crystallochemical factors cooperate in the magnetosome mineralization in magnetotactic bacteria.

Key words: magnetite, magnetosome, magnetotactic bacteria, biomineralization