title: 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.
authors.affiliation: Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands. mauri.kostiainen@aalto.fi
authors.forename: Mauri A
authors.initials: MA
authors.lastname: Kostiainen
authors.forename: Pierpaolo
authors.initials: P
authors.lastname: Ceci
authors.forename: Manuela
authors.initials: M
authors.lastname: Fornara
authors.forename: Panu
authors.initials: P
authors.lastname: Hiekkataipale
authors.forename: Oksana
authors.initials: O
authors.lastname: Kasyutich
authors.forename: Roeland J M
authors.initials: RJ
authors.lastname: Nolte
authors.forename: Jeroen J L M
authors.initials: JJ
authors.lastname: Cornelissen
authors.forename: Ryan D
authors.initials: RD
authors.lastname: Desautels
authors.forename: Johan
authors.initials: J
authors.lastname: van Lierop
mesh_terms: D001052:Apoferritins / Q000737:chemistry*; D019843:Archaeal Proteins / Q000737:chemistry; D050091:Dendrimers / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D060328:Magnetic Phenomena; D008958:Models, Molecular; D053758:Nanoparticles / Q000737:chemistry*; D009578:Nitrobenzenes / Q000737:chemistry; D055620:Optical Phenomena; D010087:Oxides / Q000737:chemistry*; D011487:Protein Conformation; D020027:Pyrococcus furiosus; D014466:Ultraviolet Rays
chemical_list: D019843:Archaeal Proteins; D050091:Dendrimers; D009578:Nitrobenzenes; D010087:Oxides; C088922:magnetoferritin; D001052:Apoferritins; D007501:Iron; C036077:nitrobenzene