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Tuning Properties of Iron Oxide Nanoparticles in Aqueous Synthesis without Ligands to Improve MRI Relaxivity and SAR

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Powder Technology Laboratory, Institute of Matesrials, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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Interdisciplinary Centre for Electron Microscopy (CIME), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza, C/Pedro Cerbuna 10, 50009 Zaragoza, Spain
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Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Mariano Esquillor s/n, 50018 Zaragoza, Spain
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Grupo de Electrónica de Potencia y Microelectrónica, I3A, Universidad de Zaragoza, 50018 Zaragoza, Spain
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Department of Radiology, University Hospital (CHUV) and University of Lausanne (UNIL), 1011 Lausanne, Switzerland
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Center for Biomedical Imaging (CIBM), 1011 Lausanne, Switzerland
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CCC-IPSB, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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Author to whom correspondence should be addressed.
Current address: nB nanoScale Biomagnetics S.L., Panamá 2, Local 1-50012-Zaragoza, Spain
Nanomaterials 2017, 7(8), 225; https://doi.org/10.3390/nano7080225
Received: 19 July 2017 / Revised: 1 August 2017 / Accepted: 2 August 2017 / Published: 18 August 2017
(This article belongs to the Special Issue Magnetic Nanoparticles in Biological Applications)
Aqueous synthesis without ligands of iron oxide nanoparticles (IONPs) with exceptional properties still remains an open issue, because of the challenge to control simultaneously numerous properties of the IONPs in these rigorous settings. To solve this, it is necessary to correlate the synthesis process with their properties, but this correlation is until now not well understood. Here, we study and correlate the structure, crystallinity, morphology, as well as magnetic, relaxometric and heating properties of IONPs obtained for different durations of the hydrothermal treatment that correspond to the different growth stages of IONPs upon initial co-precipitation in aqueous environment without ligands. We find that their properties were different for IONPs with comparable diameters. Specifically, by controlling the growth of IONPs from primary to secondary particles firstly by colloidal and then also by magnetic interactions, we control their crystallinity from monocrystalline to polycrystalline IONPs, respectively. Surface energy minimization in the aqueous environment along with low temperature treatment is used to favor nearly defect-free IONPs featuring superior properties, such as high saturation magnetization, magnetic volume, surface crystallinity, the transversal magnetic resonance imaging (MRI) relaxivity (up to r2 = 1189 mM−1·s−1 and r2/r1 = 195) and specific absorption rate, SAR (up to 1225.1 W·gFe−1). View Full-Text
Keywords: iron oxide nanoparticles; magnetic nanoparticle; aqueous synthesis; hydrothermal treatment; saturation magnetization; MRI relaxivity; specific absorption rate iron oxide nanoparticles; magnetic nanoparticle; aqueous synthesis; hydrothermal treatment; saturation magnetization; MRI relaxivity; specific absorption rate
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Bonvin, D.; Alexander, D.T.L.; Millán, A.; Piñol, R.; Sanz, B.; Goya, G.F.; Martínez, A.; Bastiaansen, J.A.M.; Stuber, M.; Schenk, K.J.; Hofmann, H.; Mionić Ebersold, M. Tuning Properties of Iron Oxide Nanoparticles in Aqueous Synthesis without Ligands to Improve MRI Relaxivity and SAR. Nanomaterials 2017, 7, 225.

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