Bioengineering Magnetic Nanoparticles in Magnetotactic Bacteria

Magnetic nanoparticles (MNPs) are in great demand in diverse modern technologies such as high-density data storage, electromagnetic shielding, and various applications for biomedicine including targeted drug delivery or hyperthermia. Compared to bulk magnets, MNPs shows unique and interesting properties, which largely dependent on their size, shape or crystal composition. The strong interest in the filed is to produce uniform-sized MNPs with desired properties required for each technological application. However, chemical synthesis of structurally perfect MNPs with narrow size distributions still remains a challenge. In contrast, magnetic nanoparticles biomineralized by natural organisms are known to show narrow size distributions, high crystal perfections that could be biosynthesized under environment-friendly reaction conditions. Our goal is to design and produce MNPs with various properties by genetically engineering Magnetospirillum magneticum AMB-1, a bacteria that can biosynthesize chains of magnetic nanoparticles (called magnetosomes). Magnetosomes are composed of magnetite (Fe3O4) nanoparticles with remarkably narrow size/shape distribution. By modifying bacterial MNPs from bottom-up and retaining its natural ability to produce them with narrow size distributions, we envision the production of “designer magnetic nanoparticles” which is otherwise difficult to achieve. We have engineered and characterized basic genetic parts, such as stable plasmids, promoters or reporters for M. magneticum. Using these genetic parts, we have changed the expression level of magnetosome genes to tune the size/shape of magnetosome nanoparticles. In the presentation, we will also discuss our attempts to decorate the surface or modify the chemical composition of MNPs.