For the first time, scientists have visualized the first steps of bacterial protein involvement in the formation of crystal seeds, or nucleation. Magnetotactic bacteria are a group of bacteria that naturally produce magnetic crystals and the protein Mms6 is thought to play an important role in this process. Inspired by the bacteria’s ability to create magnetic crystals, researchers use this protein to make similar particles in the laboratory Using in situ fluid cell transmission electron microscopy (TEM), a team of materials chemists, microscopists, and chemical engineers has imaged the process at nanometer resolution as it occurs in liquid. The Mms6 protein first self-assembles into micelles , which become visible only after binding iron from iron chloride (FeCl3) in the solution . When the scientists added sodium hydroxide (NaOH) they saw a goo-like layer form on the micelle . When more NaOH is added, the goo layer condenses to give birth to tiny iron oxide nanoparticles . These nanoparticles are thought to rearrange and grow into magnetic crystals resembling those made by bacteria. In confining nucleation to its surface, Mms6 suppresses undesired particle formation from occurring randomly elsewhere in the solution. Understanding the early phases of crystal formation enables researchers to mimic Nature’s own technology and optimize the synthesis of magnetic nanoparticles.
Nucleation of Iron Oxide Nanoparticles Mediated by Mms6 Protein in Situ