71. Raman Spectroscopy to unravel the Magnetic Properties of Iron Oxide Nanocrystals for Bio-related Applications
Martín Testa-Anta, Miguel A. Ramos-Docampo, Miguel Comesaña-Hermo, Beatriz Rivas-Murias, Verónica Salgueiriño
Nanoscale Advances (2019, in press) (DOI: 10.1039/c9na00064j).
Iron oxide nanocrystals have become a versatile tool in biomedicine by presenting low cytotoxicity while offering a wide range of tuneable magnetic properties that may be implemented in magnetic separation, drug and heat delivery or bioimaging. These capabilities rely on the unique magnetic features obtained when combining different iron oxide phases, so that an important portfolio of magnetic properties can be attained by the rational design of multicomponent nanocrystals. In this context, Raman spectroscopy constitutes an invaluable and fast-performance tool to gain insight into the different phases forming part of the nanocrystals to be used, allowing to correlate the magnetic properties with the envisaged bio-related applications.
70. Clusters of Magnetite-Maghemite Nanocrystals with a Chemically-tailored Average Diameter
Miguel A. Ramos-Docampo, Martín Testa-Anta, Beatriz Rivas-Murias, Verónica Salgueiriño
Journal of Nanoscience and Nanotechnology (2019), 19, 4930-4937 (DOI: 10.1166/jnn.2019.16788).
Clusters of magnetic nanocrystals are very advantageous if keeping the superparamagnetic state of the individual nanocrystals while taking advantage of a large total magnetic moment, as very convenient in sensing, catalysis and bio-related applications. Herein, we demonstrate how the molecular weight of poly(ethylene glycol) exerts a dominant role in controlling the final size of the clusters and the average crystallites forming them, which delineate the final magnetic properties and their potential applications.
69. Spontaneous Formation of Cold-Welded Plasmonic Nanoassemblies with Refracted Shapes for Intense Raman Scattering
Andrea Mariño-López, María Blanco-Formoso, Leonardo N. Furini, Ana Sousa-Castillo, Ecem Tiryaki, Moisés Pérez-Lorenzo, Martín Testa-Anta, Verónica Salgueiriño, Nicholas A. Kotov, Ramón A. Álvarez-Puebla, Miguel A. Correa-Duarte
Langmuir (2019), 35, 4110-4116 (DOI: 10.1021/acs.langmuir.9b00234).
68. Antiphase Boundaries in Truncated Octahedron-shaped Zn-doped Magnetite Nanocrystals
Nerio Fontaiña-Troitiño, Miguel A. Ramos-Docampo, Martín Testa-Anta, Benito Rodríguez-González, Manuel Bañobre-López, Laura Bocher, Keith P. McKenna, Verónica Salgueiriño
J. Materials Chemistry C (2018) 6, 12800-12807 (DOI: 10.1039/C8TC05731A).
The presence of antiphase boundaries with local ferromagnetic coupling is herein related to the magnetic performance of truncated octahedron-shaped zinc-doped magnetite nanocrystals. Atomic resolution STEM imaging reveals the presence of these antiphase boundaries perpendicular to the [111] direction of the spinel structure of the nanocrystals. Magnetic characterization and DFT calculations indicate a local ferromagnetic order, originating from Fe-Fe enrichment at these individual lattice defects in the nanocrystals, as the underlying cause of the magnetic response measured.
67. Shaping Iron Oxide Nanocrystals for Magnetic Separation Applications
Martín Testa-Anta, Sara Liébana-Viñas, Beatriz Rivas-Murias, Benito Rodríguez-González, Michael Farle, Verónica Salgueiriño
Nanoscale (2018), 10, 20462-20467 (DOI: 10.1039/C8NR05864D).
Iron oxide nanostructures are attractive for a variety of bio-related applications given their wide range of magnetic properties. Here, we report on the study of the magnetophoretic mobility of octapod-shaped nanocrystals, which we relate to stoichiometry, quality and elongation in the <111> direction of these cubic structures. This special morphology combines magnetocrystalline anisotropies, increases shape anisotropy and hinders the formation of an epitaxial wüstite-magnetite interface. As a result, one obtains nanocrystals with large magnetic susceptibility and small coercivity, that is, with optimum characteristics for magnetic guidance, separation, and drug delivery, due to the increased magnetophoretic mobility displayed.
