Che Dji Lyns Verel, Kaddah Roua, Girardet Thomas, Fleutot Solenne, Bouguet-Bonnet Sabine
CRM2 (Cristallographie, Résonance Magnétique et Modélisations), CNRS, Université de Lorraine, Vandœuvre-lès-Nancy F-54500, France.
IJL (Institut Jean Lamour), CNRS, Université de Lorraine, Nancy F-5400, France.
Langmuir. 2024 Oct 22;40(42):22089-22097. doi: 10.1021/acs.langmuir.4c02448. Epub 2024 Oct 11.
Due to weak exchange interactions, magnetite particles at a critical diameter of about 20 nm are considered monodomain. At this size, they exhibit a phenomenological magnetic property called superparamagnetism, making them useful as magnetic resonance imaging contrast agents, or MRI CAs. However, questions persist regarding the impact of using different physiological solvents and varying the environment in which these particles are dispersed on their performance, determined by their relaxivity. A colloidal suspension of superparamagnetic iron oxide nanoparticles (SPIONs) electrostatically stabilized by citrate ligand was synthesized using a fast, reliable, and reproducible developed microwave approach, ensuring high stability over time at pH 7. We studied the effects of three physiological media on these MRI CAs. Ultrapure water was used for the synthesis, while phosphate-buffered saline and physiological liquid were used to disperse the nanoparticles, as these media contain essential electrolytes for the functioning of the human body. The SPIONs underwent systematic characterizations to determine their physicochemical and magnetic properties. This study reports the longitudinal relaxivities of SPIONs at medically relevant magnetic field strengths. Field dependence of their relaxivity (efficacy) was evaluated using a nuclear magnetic resonance dispersion (NMRD) profile measured over a wide range of proton resonance frequencies between 5 kHz and 600 MHz. The Roch et al. model (Roch, A.; et al. , 5403-5411) was used to analyze the NMRD profile and evaluate the impact of SPIONs on water proton relaxation in the different redispersion media. It was observed in this study that the dynamics of water protons are not influenced by the redispersion media of these citrate-coated SPIONs. However, the presence of salt ions notably reduces their relaxivities by lowering the saturation magnetization of SPIONs.
由于交换相互作用较弱，临界直径约为20 nm的磁铁矿颗粒被认为是单畴的。在这个尺寸下，它们表现出一种称为超顺磁性的现象学磁性特性，这使得它们可用作磁共振成像造影剂，即MRI造影剂。然而，关于使用不同的生理溶剂以及改变这些颗粒分散环境对其性能（由弛豫率决定）的影响，仍然存在问题。使用一种快速、可靠且可重复的微波方法合成了由柠檬酸盐配体静电稳定的超顺磁性氧化铁纳米颗粒（SPIONs）胶体悬浮液，确保在pH 7时随时间具有高稳定性。我们研究了三种生理介质对这些MRI造影剂的影响。合成过程中使用了超纯水，而磷酸盐缓冲盐水和生理液体用于分散纳米颗粒，因为这些介质含有对人体功能至关重要的电解质。对SPIONs进行了系统表征以确定其物理化学和磁性特性。本研究报告了SPIONs在医学相关磁场强度下的纵向弛豫率。使用在5 kHz至600 MHz的宽质子共振频率范围内测量的核磁共振色散（NMRD）谱来评估其弛豫率（效能）的场依赖性。使用Roch等人的模型（Roch, A.; 等人, 5403 - 5411）来分析NMRD谱并评估SPIONs对不同再分散介质中水质子弛豫的影响。在本研究中观察到，这些柠檬酸盐包覆的SPIONs的再分散介质不会影响水质子的动力学。然而，盐离子的存在会通过降低SPIONs的饱和磁化强度显著降低其弛豫率。
