Biogenic nanoparticles: production, characterization, and application of bacterial magnetosomes

The ability of magnetotactic bacteria (MTB) to navigate along magnetic field lines is based on unique nanosized organelles (magnetosomes), which are membrane-enclosed intracellular crystals of a magnetic iron mineral that assemble into highly ordered chain-like structures. The biomineralization of magnetosomes is a process with genetic control over the accumulation of iron, the deposition of the magnetic crystal within a specific compartment, as well as the assembly, alignment and intracellular organization of particle chains. Magnetite crystals produced by MTB have uniform species-specific morphologies and sizes, which are mostly unknown from inorganic systems. The unusual characteristics of magnetosome particles have attracted a great interdisciplinary interest and inspired numerous ideas for their biotechnological application. In this article, we summarize the current knowledge of magnetosome biomineralization in bacteria. In addition, we will present results on the mass production, as well as the biochemical and physico-chemical analysis and functionalization of bacterial magnetosomes, with emphasis on their characterization as a novel class of magnetic nanoparticles. Finally, we describe the potential of magnetosomes in various biomedical and technological applications