Hierarchical Self-Assembly and Optical Disassembly for Controlled Switching of Magnetoferritin Nanoparticle Magnetism

Abstract

Protein cages such as ferritin and viral capsids are interesting building blocks for nanotechnology due to their monodisperse structure and ability to encapsulate various functional moieties. Here we show that recombinant ferritin protein cages encapsulating Fe(3)O(4)-γ-Fe(2)O(3) iron oxide (magnetoferritin) nanoparticles and photodegradable Newkome-type dendrons self-assemble into micrometer-sized complexes with a face-centered-cubic (fcc) superstructure and a lattice constant of 13.1 nm. The magnetic properties of the magnetoferritin particles are affected directly by the hierarchical organization. Magnetoferritin nanoparticles dispersed in water exhibit typical magnetism of single domain noninteracting nanoparticles; however, the same nanoparticles organized into fcc superstructures show clearly the effects of the altered magnetostatic (e.g., dipole-dipole) interactions by exhibiting, for example, different hysteresis of the field-dependent magnetization. The magnetoferritin-dendron assemblies can be efficiently disassembled by a short optical stimulus resulting in release of free magnetoferritin particles. After the triggered release the nanomagnetic properties of the pristine magnetoferritin nanoparticles are regained.

Intra- and interparticle magnetism of cobalt-doped iron-oxide nanoparticles encapsulated in a synthetic ferritin cage

“…1. Size analysis reported previously for un-doped Fe-oxide nanoparticles obtained using the same synthesis procedure and having the same metal loading showed highly uniform spherical particles with an average particle diameter of 6.5±0.5 nm 3,4 .…”

“…Pyrococcus furiosus ferritin (PfFt), in particular, has several unique advantages, such as enabling a "gentle" reactive environment that can lead to the formation of materials that are difficult to obtain at the nanoscale using conventional free solution environments 1 , a high thermal stability 2 , and producing well crystallized samples 1 due to the relatively few internal nucleation sites for mineralization; qualities which lead to good tunability and a high quality nanoparticle that is ideal for the examination of nanoparticle magnetism. Importantly, ferritin-based nanoparticles are also particularly well suited as building blocks for macroscopic self-assembly that provides an avenue for the study of dipolar-driven magnetism 1, [3][4][5] .…”

Nanoscale device architectures derived from biological assemblies: The case of tobacco mosaic virus and (apo)ferritin

“…For example, magnetic Fe 3 O 4 75) 41,[84][85][86][87] for magnetic resonance imaging, 32,46) and even as the core of a magnonic device. 88) In analogy, Co(O)OH 89) 91) Many metal hydroxide NPs can be grown from the respective metal ion without an oxidizer.…”

Biomimetic Materials Synthesis from Ferritin-Related, Cage-Shaped Proteins

“…Another approach to control the magnetic properties of ferritin-enclosed NPs consists in the creation of high-order structures based on ferritin cages (Kostiainen et al, 2011 …”