78. Magnetically Induced CO2 Methanation using Exchange-coupled Spinel Ferrites in Cuboctahedron-shaped Nanocrystals
Beatriz Rivas-Murias, Juan M. Asensio, Nicolas Mille, Benito Rogríguez-González, Pier-Francesco Fazzini, Julian Carrey, Bruno Chaudret and Verónica Salgueiriño
Angewandte Chemie I. Ed. (2020, in press) (DOI: 10.1002/anie.202004908).
Magnetically induced catalysis can be promoted taking advantage of optimal heating properties from the magnetic nanoparticles to be employed. However, when unprotected, these heating agents that are usually air-sensitive, get sintered under the harsh catalytic conditions. In this context, we present, to the best of our knowlege, the first example of air-stable magnetic nanoparticles that: 1) show excellent performance as heating agents in the CO2 methanation catalyzed by Ni/SiRAlOx, with CH4 yields above 95%, and 2) do not sinter under reaction conditions. To attain both characteristics we demonstrate, first the exchange-coupled magnetic approach as an alternative and effective way to tune the magnetic response and heating efficiency, and second, the chemical stability of cuboctahedron-shaped core-shell hard CoFe2O4 - soft Fe3O4 nanoparticles.
77. Iron assisted Synthesis of highly Monodisperse and Magnetic Citrate-stabilized Small Silver Nanoparticles
Maria Blanco-Formoso, Mariacristina Turino, Beatriz Rivas-Murias, Luca Guerrini, Alexey Shavel, Roberto de la Rica, Miguel A. Correa-Duarte, Verónica Salgueiriño, Nicolás Pazos-Pérez and Ramón Álvarez-Puebla
J. Phys. Chem. C (2020), 124, 3270-3276 (DOI: 10.1021/acs.jpcc.9b10606).
Herein, we present an optimized bottom-up approach for the fabrication of homogeneous small spherical silver nanoparticles, with average diameter sizes ranging from 10 to 30 nm and the associated plasmon resonances located between 390 and 410 nm. The presented method relies on the use of tiny amounts of Fe(III) as silver dopant during the growth process, which enables the production of very homogeneous nanoparticles (standard deviations < 6%). The characterization of the obtained materials with surface-enhanced Raman scattering spectroscopy shows optical enhancing properties similar, or even better, than those observed with standard silver nanoparticles. Moreover, these noble nanomaterials are also endorsed with an intrinsic magnetic functionality.
76. Recent Advances in Nano- and Micromotors
Marina Fernández-Medina, Miguel A. Ramos-Docampo, Ondrej Hovorka, Verónica Salgueiriño and Brigitte Städler
Advanced Functional Materials (2020), 1908283 (DOI: 10.1002/adfm.201908283).
75. Partial FeO-Fe3O4 Phase Transition along the <111> Direction of the Cubic Crystalline Structure in Iron Oxide Nanocrystals
Martín Testa-Anta, Benito Rodríguez-González and Verónica Salgueiriño
Particle & Particle Systems Characterization (2019), 36, 1900283 (DOI: 10.1002/ppsc.201900283).
The iron oxide nanocrystals described herein stem from a ketonic decarboxylation reaction which fosters the delivery of -FeO- as an intermedium product. This intermedium product working as a monomer nucleates into FeO seeds which grow to attain a cubic shape with tips. This kinetically-controlled second stage of growth favors the deposition of -FeO- at the apexes and promotes a partial topochemical FeO to Fe3O4 phase transition mainly along the elongated <111> direction of the cubic crystalline structures.
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), 13, 12192-12205 (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.