Synthesis, physicochemical characterization and MR relaxometry of aqueous ferrofluids.
Synthesis, physicochemical characterization and MR relaxometry of aqueous ferrofluids.
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DOI：
10.1166/jnn.2008.312
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发表时间：
2008-05
影响因子：
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通讯作者：
M. Hodenius;T. Niendorf;G. Krombach;W. Richtering;T. Eckert;H. Lueken;Manfred Speldrich;R. Günther;M. Baumann;S. Soenen;M. de Cuyper;T. Schmitz-Rode
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文献类型：
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作者：
M. Hodenius;T. Niendorf;G. Krombach;W. Richtering;T. Eckert;H. Lueken;Manfred Speldrich;R. Günther;M. Baumann;S. Soenen;M. de Cuyper;T. Schmitz-Rode
描述了基于铁磁流体的 MR 造影剂的合成和表征，该造影剂提供的 R2* 多功能性超出了阿魏卡博群 (ferucarbotran)。用十二烷酸 (a)、油酸 (b)、十二胺 (c)、柠檬酸 (d) 或酒石酸 (e) 稳定磁铁矿核后形成铁磁流体。核心尺寸是从 TEM 显微照片中推断出来的。磁性通过SQUID磁力测定法测定。通过动态光散射测量来确定流体动力学粒径。 Zeta 电位通过结合激光多普勒测速法和相位分析光散射来测量。通过比色法评估铁含量。使用均质铁磁流体样品在体外进行包括 R1 和 R2* 的 MR 弛豫测量。铁磁流体 a、b 和 c 的平均核心直径等于 9.4 +/- 2.8 nm，铁磁流体 d 和 e 的平均核心直径约为 2 nm。 300 K 下的磁化测量揭示了干燥的 9 nm 直径磁芯的超顺磁行为以及铁磁流体 d 和 e 的干燥磁芯的类顺磁行为。铁含量在 32-75 mg Fe/mL 之间，反映了铁磁流体的高颗粒浓度。流体动力学粒径等于 100-120 nm（a、b 和 c）。对于涂有阴离子的铁磁流体a、b、d和e，测定了-27.5 mV和-54.0 mV之间的强负zeta电位值，并且发现覆盖有阳离子十二烷基铵离子的铁磁流体c的+33.5 mV的正zeta电位值。 MR 松弛测量得出的 R1 值为 1.9 +/- 0.3 (a)、4.0 +/- 0.8 (b)、5.2 +/- 1.0 (c)、0.124 +/- 0.002 (d) 和 0.092 +/- 0.005 s(-1) mM(-1) (e)，R2* 值为 856 +/- 24(a)、729+/-16(b)、922+/-29(c)、1.7+/-0.05(d)和0.49+/-0.05s(-1)mM(-1)(e)。因此，合成的铁磁流体揭示了广泛的 R2* 弛豫率。因此，各种 MR 造影剂在处理恶性组织靶向或分子成像的研究中具有巨大的潜力。
The synthesis and characterization of ferrofluid based MR contrast agents, which offer R2* versatility beyond that of ferucarbotran, is described. Ferrofluids were formed after stabilizing magnetite cores with dodecanoic acid (a), oleic acid (b), dodecylamine (c), citric acid (d) or tartaric acid (e). Core sizes were deduced from TEM micrographs. Magnetic properties were determined by SQUID magnetometry. Hydrodynamic particle diameters were determined by dynamic light scattering measurements. Zeta potentials were measured by combining laser Doppler velocimetry and phase analysis light scattering. Iron contents were evaluated colorimetrically. MR relaxometry including R1 and R2* was conducted in vitro using homogeneous ferrofluid samples. The average core diameters of ferrofluids a, b and c equaled 9.4 +/- 2.8 nm and approximately 2 nm for ferrofluids d and e. Magnetization measurements at 300 K revealed superparamagnetic behaviour for the dried 9 nm diameter cores and paramagnetic-like behaviour for the dried cores of ferrofluids d and e. Iron contents were between 32-75 mg Fe/mL, reflecting the ferrofluids' high particle concentrations. Hydrodynamic particle diameters equaled 100-120 nm (a, b and c). For the ferrofluids a, b, d and e coated with anions, strong negative zeta potential values between -27.5 mV and -54.0 mV were determined and a positive zeta potential value of +33.5 mV was found for ferrofluid c, covered with cationic dodecylammonium ions. MR relaxometry yielded R1-values of 1.9 +/- 0.3 (a), 4.0 +/- 0.8 (b), 5.2 +/- 1.0 (c), 0.124 +/- 0.002 (d) and 0.092 +/- 0.005 s(-1) mM(-1) (e), and R2*-values of 856 +/- 24 (a), 729 +/- 16 (b), 922 +/- 29 (c), 1.7 +/- 0.05 (d) and 0.49 +/- 0.05 s(-1) mM(-1) (e). Thus, the synthesized ferrofluids reveal a broad spectrum of R2* relaxivities. As a result, the various MR contrast agents have a great potential to be used in studies dealing with malignant tissue targeting or molecular imaging.