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A. Wolff, W. Hetaba, M. Wißbrock, S. Löffler, N. Mill, K. Eckstädt, A. Dreyer, I. Ennen, N. Sewald, P. Schattschneider, A. Hütten:
"Oriented attachment explains cobalt ferrite nanoparticle growth in bioinspired syntheses";
Beilstein Journal of Nanotechnology, 5 (2014), 210 - 218.

Oriented attachment has created a great debate about the description of crystal growth throughout the last decade. This aggregationbased
model has successfully described biomineralization processes as well as forms of inorganic crystal growth, which could not
be explained by classical crystal growth theory. Understanding the nanoparticle growth is essential since physical properties, such
as the magnetic behavior, are highly dependent on the microstructure, morphology and composition of the inorganic crystals. In this
work, the underlying nanoparticle growth of cobalt ferrite nanoparticles in a bioinspired synthesis was studied. Bioinspired
syntheses have sparked great interest in recent years due to their ability to influence and alter inorganic crystal growth and therefore
tailor properties of nanoparticles. In this synthesis, a short synthetic version of the protein MMS6, involved in nanoparticle formation
within magnetotactic bacteria, was used to alter the growth of cobalt ferrite. We demonstrate that the bioinspired nanoparticle
growth can be described by the oriented attachment model. The intermediate stages proposed in the theoretical model,
including primary-building-block-like substructures as well as mesocrystal-like structures, were observed in HRTEM measurements.
These structures display regions of substantial orientation and possess the same shape and size as the resulting discs. An
increase in orientation with time was observed in electron diffraction measurements. The change of particle diameter with time
agrees with the recently proposed kinetic model for oriented attachment.

bioinspired synthesis; cobalt ferrite nanoparticles; nanoparticle growth; oriented attachment; polypeptide

http://dx.doi.org/10.3762/bjnano.5.23