Elucidating the Bioinspired Synthesis Process of Magnetosomes-Like Fe₃O₄ Nanoparticles

Iron oxide nanoparticles are a kind of important biomedical nanomaterials. Although their industrial-scale production can be realized by the conventional coprecipitation method, the controllability of their size and morphology remains a huge challenge. In this study, a kind of synthetic polypeptide Mms6-28 which mimics the magnetosome protein Mms6 is used for the bioinspired synthesis of Fe₃O₄ nanoparticles (NPs). Magnetosomes-like Fe₃O₄ NPs with uniform size, cubooctahedral shape, and smooth crystal surfaces are synthesized via a partial oxidation process. The Mms6-28 polypeptides play an important role by binding with iron ions and forming nucleation templates and are also preferably attached to the [100] and [111] crystal planes to induce the formation of uniform cubooctahedral Fe₃O₄ NPs. The continuous release and oxidation of Fe²⁺ from pre-formed Fe²⁺-rich precursors within the Mms6-28-based template make the reaction much controllable. The study affords new insights into the bioinspired- and bio-synthesis mechanism of magnetosomes.