Saeidi Hamidreza, Mozaffari Morteza, Ilbey Serhat, Dutz Silvio, Zahn Diana, Azimi Gholamhassan, Bock Michael
Faculty of Physics, University of Isfahan, Isfahan 8174673441, Iran.
Department of Radiology, Medical Physics, Medical Center University of Freiburg, Faculty of Medicine, University of Freiburg, Killianstr. 5a, 79106 Freiburg, Germany.
Nanomaterials (Basel). 2023 Jan 12;13(2):331. doi: 10.3390/nano13020331.
Magnetic nanoparticles (MNPs) have been widely applied as magnetic resonance imaging (MRI) contrast agents. MNPs offer significant contrast improvements in MRI through their tunable relaxivities, but to apply them as clinical contrast agents effectively, they should exhibit a high saturation magnetization, good colloidal stability and sufficient biocompatibility. In this work, we present a detailed description of the synthesis and the characterizations of europium-substituted Mn-Zn ferrite (MnZnEuFeO, = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.15, herein named MZF for = 0.00 and EuMZF for others). MNPs were synthesized by the coprecipitation method and subsequent hydrothermal treatment, coated with citric acid (CA) or pluronic F127 (PF-127) and finally characterized by X-ray Diffraction (XRD), Inductively Coupled Plasma (ICP), Vibrating Sample Magnetometry (VSM), Fourier-Transform Infrared (FTIR), Dynamic Light Scattering (DLS) and MRI Relaxometry at 3T methods. The XRD studies revealed that all main diffraction peaks are matched with the spinel structure very well, so they are nearly single phase. Furthermore, XRD study showed that, although there are no significant changes in lattice constants, crystallite sizes are affected by europium substitution significantly. Room-temperature magnetometry showed that, in addition to coercivity, both saturation and remnant magnetizations decrease with increasing europium substitution and coating with pluronic F127. FTIR study confirmed the presence of citric acid and poloxamer (pluronic F127) coatings on the surface of the nanoparticles. Relaxometry measurements illustrated that, although the europium-free sample is an excellent negative contrast agent with a high relaxivity, it does not show a positive contrast enhancement as the concentration of nanoparticles increases. By increasing the europium to = 0.15, relaxivity increased significantly. On the contrary, europium substitution decreased relaxivity due to a reduction in saturation magnetization. The ratio of / decreased from 152 for the europium-free sample to 11.2 for = 0.15, which indicates that MnZnEuFeO is a suitable candidate for dual-mode MRI contrast agent potentially. The samples with citric acid coating had higher and lower relaxivities than those of pluronic F127-coated samples.
磁性纳米颗粒（MNPs）已被广泛用作磁共振成像（MRI）造影剂。MNPs 通过其可调的弛豫率在 MRI 中显著改善对比度，但要有效地将它们用作临床造影剂，它们应表现出高饱和磁化强度、良好的胶体稳定性和足够的生物相容性。在这项工作中，我们详细描述了铕取代的锰锌铁氧体（MnZnEuFeO，(x) = 0.00、0.02、0.04、0.06、0.08、0.10 和 0.15，此处(x) = 0.00 时命名为 MZF，其他情况命名为 EuMZF）的合成与表征。通过共沉淀法和随后的水热处理合成 MNPs，用柠檬酸（CA）或普朗尼克 F127（PF - 127）包覆，最后通过 X 射线衍射（XRD）、电感耦合等离子体（ICP）、振动样品磁强计（VSM）、傅里叶变换红外光谱（FTIR）、动态光散射（DLS）和 3T 场强下的 MRI 弛豫测量法进行表征。XRD 研究表明，所有主要衍射峰都与尖晶石结构非常匹配，因此它们几乎是单相的。此外，XRD 研究表明，尽管晶格常数没有显著变化，但微晶尺寸受铕取代的影响很大。室温磁强测量表明，除矫顽力外，饱和磁化强度和剩余磁化强度均随铕取代量的增加以及用普朗尼克 F127 包覆而降低。FTIR 研究证实了纳米颗粒表面存在柠檬酸和泊洛沙姆（普朗尼克 F127）涂层。弛豫测量表明，尽管无铕样品是具有高(r_2)弛豫率的优异阴性造影剂，但随着纳米颗粒浓度的增加，它并未显示出阳性对比增强。将铕含量增加到(x) = 0.15 时，(r_1)弛豫率显著增加。相反，由于饱和磁化强度降低，铕取代降低了(r_2)弛豫率。(r_1/r_2)的比值从无铕样品的 152 降至(x) = 0.15 时的 11.2，这表明 MnZnEuFeO 可能是双模式 MRI 造影剂的合适候选物。柠檬酸包覆的样品比普朗尼克 F127 包覆的样品具有更高的(r_1)和更低的(r_2)弛豫率。
