David García-Soriano1, Rebeca Amaro1, Nuria Lafuente-Gómez1, Paula Milán-Rois1, Álvaro Somoza2, Cristina Navío1, Fernando Herranz3, Lucía Gutiérrez4, Gorka Salas5. 1. IMDEA Nanociencia, Campus Universitario de Cantoblanco, 28049 Madrid, Spain. 2. IMDEA Nanociencia, Campus Universitario de Cantoblanco, 28049 Madrid, Spain; Unidad Asociada de Nanobiotecnología (CNB-CSIC e IMDEA Nanociencia), Spain. 3. Instituto de Química Médica, CSIC, Juan de la Cierva 3, 28006 Madrid and CIBERES, Spain. 4. Department of Analytical Chemistry, Universidad de Zaragoza, INA, ICMA and CIBER-BBN, C/Mariano Esquillor, s/n, 50018 Zaragoza, Spain. 5. IMDEA Nanociencia, Campus Universitario de Cantoblanco, 28049 Madrid, Spain; Unidad Asociada de Nanobiotecnología (CNB-CSIC e IMDEA Nanociencia), Spain. Electronic address: gorka.salas@imdea.org.
Abstract
HYPOTHESIS: Superparamagnetic MnxFe3-xO4 nanoparticles are promising materials for applications in biomedicine and other fields. Small variations in the Mn/Fe ratio have a strong impact on the properties of the nanoparticles. Those variations may be caused by the synthesis itself and by common post-synthesis manipulations like surface modification. EXPERIMENTS: Mn-ferrite nanoparticles have been prepared changing systematically the Mn/Fe ratio of the metal precursors and repeating each reaction three times. Nanoparticles were subjected to surface modification with two different and typical molecules to stabilize them in aqueous media. The discrepancy in the Mn/Fe ratios of the precursors with the ones measured after the synthesis and the surface modification have been studied, as well as its impact on the saturation magnetization, blocking temperature, contrast enhancement for magnetic resonance imaging, magnetic heating, and on the cytotoxicity. FINDINGS: Mn is incorporated in the nanoparticles in a relatively lower amount than Fe and, as this report shows for the first time, both Mn and Fe ions leach out from the nanoparticles during the surface modification step. The blocking temperature decreases exponentially as the Mn/Fe ratio increases. The transverse and longitudinal relaxation times and the magnetic heating ability change appreciably even with small variations in the composition.
HYPOTHESIS: Superparamagnetic MnxFe3-xO4 nanoparticles are promising materials for applications in biomedicine and other fields. Small variations in the Mn/Fe ratio have a strong impact on the properties of the nanoparticles. Those variations may be caused by the synthesis itself and by common post-synthesis manipulations like surface modification. EXPERIMENTS: Mn-ferrite nanoparticles have been prepared changing systematically the Mn/Fe ratio of the metal precursors and repeating each reaction three times. Nanoparticles were subjected to surface modification with two different and typical molecules to stabilize them in aqueous media. The discrepancy in the Mn/Fe ratios of the precursors with the ones measured after the synthesis and the surface modification have been studied, as well as its impact on the saturation magnetization, blocking temperature, contrast enhancement for magnetic resonance imaging, magnetic heating, and on the cytotoxicity. FINDINGS: Mn is incorporated in the nanoparticles in a relatively lower amount than Fe and, as this report shows for the first time, both Mn and Fe ions leach out from the nanoparticles during the surface modification step. The blocking temperature decreases exponentially as the Mn/Fe ratio increases. The transverse and longitudinal relaxation times and the magnetic heating ability change appreciably even with small variations in the composition.
Authors: Zichun Yan; Anish Chaluvadi; Sara FitzGerald; Sarah Spence; Christopher Bleyer; Jiazhou Zhu; Thomas M Crawford; Rachel B Getman; John Watt; Dale L Huber; O Thompson Mefford Journal: Nanoscale Adv Date: 2022-08-25