Protein-mediated synthesis of uniform superparamagnetic magnetite nanocrystals

TitleProtein-mediated synthesis of uniform superparamagnetic magnetite nanocrystals
Publication TypeJournal Article
Year of Publication2007
AuthorsProzorov T, Mallapragada SK, Narasimhan B, Wang LJ, Palo P, Nilsen-Hamilton M, Williams TJ, Bazylinski DA, Prozorov R, Canfield PC
Journal TitleAdvanced Functional Materials
Date PublishedApr
Type of ArticleArticle
ISBN Number1616-301X
Accession NumberISI:000246414100014

Magnetite nanocrystals are synthesized in the presence of a recombinant Mms6 protein thought to be involved in the biomineralization of bacterial magnetite magnetosomes, the mammalian iron-storage protein, ferritin, and two proteins not known to bind iron, lipocalin (Lcn2) and bovine serum albumin (BSA). To mimic the conditions at which magnetite nanocrystals are formed in magnetotactic bacteria, magnetite synthesis is performed in a polymeric gel to slow down the diffusion rates of the reagents. Recombinant Mms6 facilitates formation of ca. 30 run single-domain,. uniform magnetite nanocrystals in solution, as verified by using transmission electron microscopy analysis and magnetization measurements. The nanocrystals formed in the presence of ferritin, Lcn2, and BSA, do not exhibit the uniform sizes and shapes observed for those produced in the presence of Mms6. Mms6-derived magnetite nanoparticles show the largest magnetization values above the blocking temperature, as well as the largest magnetic susceptibility compared to those of the nanomaterials synthesized with other proteins. The latter is indicative of a substantial effective magnetic moment per particle, which is consistent with the presence of magnetite with a well-defined crystalline structure. The combination of electron microscopy analysis and magnetic measurements confirms our hypothesis that Mms6 promotes the shape-selective formation of uniform superparamagnetic nanocrystals. This provides a unique bioinspired route for synthesis of uniform magnetite nanocrystals.

Alternate JournalAdv. Funct. Mater.