Biomimetic Formation of Magnetite Nanoparticles

Magnetic nanoparticles have both fundamental and technological applications, ranging from environmental to life sciences, and from nanotechnology to mechanics. Magnetotactic bacteria produce magnetic nanoparticles called magneto-somes; these magnetite crystals are embedded in an organic matrix, and have tailored properties. The crystals have a permanent magnetization, though laboratory strains have been created which produce magnetosomes of superparamagnetic size. These magnetic properties, together with the lipidic membrane, confer a very high nanobiotechnological potential to the magnetosomes. The production of magnetosomes in high quantities is problematic, however, and as a consequence biomimetic approaches have been developed in an attempt to mimic the formation of materials observed in the living world. In this chapter, several such synthetic pathways are presented. The best biomimetic approach will be developed when it is realized how these bacteria biomineralize their magnetic inclusions. At that point, the process will be reproduced to permit the development of novel, abiotic routes of synthesis. Attempts to circumvent the problems of working with slow-growing magnetotactic bacteria, by using an "abiomimetic" approach to understand biomineralization, are presented. Finally, an approach coupling in-vitro and in-vivo experiments is described which should not only pave the way towards an understanding of the magnetite biomineralization process by magnetotactic bacteria, but also aid in the development of successful biomimetic synthetic routes.