Mesoporous nanorods made magnetic: a versatile platform for theranostics
Jheng-Guang Li,1 Giulia Fornasieri,2 Anne Bleuzen,2, Martí Gich,3 Alexandre Gloter,1 Frédéric Bouquet,1 and Marianne Impéror-Clerc1
Alignment under Magnetic Field of Mixed Fe2O3/SiO2 Colloidal Mesoporous Particles Induced by Shape Anisotropy Small, 12 (43), 5981-5988, 2016
High aspect ratio silica rods with its hexagonally ordered mesopores along the rod axis partially filled with maghemite (γ-Fe2O3) nanoparticles. Small angle X-ray scattering shows that a liquid dispersion of the composit rods are easily aligned under a magnetic field
Composite materials based in the combination of iron oxide nanoparticles with spheres of mesoporous silica have been widely investigated for its prospective theranostic applications. In this work we delve into the study of these promising systems in highly anisotropic rod-like geometries. Here, building on previous knowledge on preparing high aspect ratio silica rods with hexagonally ordered mesopores, we synthesised iron oxide nanoparticles of different inside the mesoporous silica channels. This was achieved by impregnating these rods with molten iron nitrate by capillarity followed by thermal annealings at different temperatures. Thanks to the ordered porosity we could calculate the maximum amount of iron nitrate in order to soak the rods while letting no excess outside the mesopores. The final material consists of silica rods with ordered arrays of iron oxide nanoparticles inside its mesoporous channels, which preserve a significant porosity thanks to the larger density of iron oxide compared to iron nitrarte. An appealing property of this material is that that once dispersed in a liquid the rods easily align under a magnetic field, with the rod axis pointing along the field gradient.
This works paves the way for developing engineered magnetic objects in the rod shape as a new family of theranostic agents. In particular, one can envisage radically new properties and advantages compared to the magnetic nanoparticles used so far. Rods will show enhanced field guidance due to its geometry and large magnetic moment and, more importantly, a mechanical response which can be activated by an AC magnetic field. Moreover, since the degree of filling of the nanochannel filling by magnetic particles can be controlled, it will be possible to incorporate other materials to design multimodal agents for theranostic purposes, with inorganic nanoparticles as contrast agents for magnetic resonance imaging and computed tomography and at the same time encapsulating selected drugs.
1 Laboratoire de Physique des Solides, CNRS Orsay, France 2 Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris-Sud, Université Paris-Saclay, France 3 Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Spain
Institut de Ciència de Materials de Barcelona Campus de la UAB 08193 Bellaterra, SPAIN