74. Microswimmers with Heat Delivery Capacity for 3D Cell Spheroid Penetration
Miguel A. Ramos-Docampo, Marina Fernández-Medina, Essi Taipaleenmäki, Ondrej Hovorka, Verónica Salgueiriño and Brigitte Städler
ACS Nano (2019), in press (DOI: 10.1021/acsnano.9b06869).
We report microswimmers that employ collagen, a major extracellular matrix constituent, as fuel and that have the ability to deliver heat via incorporated magnetic nanoparticles when exposed to an alternating magnetic field. Their assembly and heating properties are outlined followed by the assessment of their calcium-triggered mobility in aqueous solution and collagen gels. Furthermore, the successful penetration of the swimmers into 3D cell spheroids upon exposure to the alternating magnetic field implies that the cell viability becomes impared due to the locally delivery heat.
73. Spin Frustration Drives Exchange Bias Sign Crossover in CoFe2O4-Cr2O3 Nanocomposites
Martín Testa-Anta, Beatriz Rivas-Murias, Verónica Salgueiriño
Advanced Functional Materials (2019), 1900030 (DOI: 10.1002/adfm.201900030).
A combined Raman spectroscopy and magnetometry study of CoFe2O4-Cr2O3 nanocomposites demonstrates the presence of spin-phonon interactions and exchange bias at the interface between the ferrimagnetic CoFe2O4 and the antiferromagnetic and magnetoelectric Cr2O3 phases. The pinned layer of uncompensated spins at the surface of the chromium oxide nanocrystals provides a source of unidirectional anisotropy and changes the sign of the exchange bias when transitioning from a canted to a frustrated situation, that is, as increasing the percentage of CoFe2O4 or decreasing the percentage of Cr2O3 in the composites. This assessment of the distinctive interfaces attained in the final oxide heterostructures offers a prospective route for hybrid materials on which upholding a magnetoelectric effect.
72. Titanate Nanowires as One-Dimensional Hot Spot Generators for Broadband Au-TiO2 Photocatalysis
Yoel Negrín-Montecelo, Martín Testa-Anta, Laura Marín-Caba, Moisés Pérez-Lorenzo, Verónica Salgueiriño, Miguel A. Correa-Duarte, Miguel Comesaña-Hermo
Nanomaterials (2019), 9, 990 (DOI: 10.3390/nano9070990).
The use of titanate nanowires as advantageous substrates for the development of hybrid photocatalysts are herein reported, considering TEM, XRD and Raman for an in-depth characterization of the chemical and structural properties of these objects. These titanate nanowires functionalized with Au nanorods and TiO2 nanoparticles offer a new class of hybrid nanostructures with outstanding photocatalytic features. These extraordinary properties are explained as a consequence of the anisotropic morphology of the substrates and the preferential directed 1D assembly of the Au nanorods, thus leading to the controlled formation of plasmonic hot spots.
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), 1, 2086-2103 (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.