Cubic versus hexagonal - effect of host crystallinity on the T1 shortening behaviour of NaGdF4 nanoparticles.
Cubic versus hexagonal - effect of host crystallinity on the T1 shortening behaviour of NaGdF4 nanoparticles.
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DOI：
10.1039/c9nr00241c
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发表时间：
2019-04
期刊：
影响因子：
6.7
通讯作者：
Nan Liu;R. Marin;Yacine Mazouzi;G. Cron;A. Shuhendler;Eva Hemmer
中科院分区：
文献类型：
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作者：
Nan Liu;R. Marin;Yacine Mazouzi;G. Cron;A. Shuhendler;Eva Hemmer
由于Gd 3+离子的顺磁性，氟化钆钠（NaGdF 4）纳米颗粒是作为T1缩短磁共振成像（MRI）造影剂的有前途的候选者。这些纳米颗粒的尺寸和表面改性对质子弛豫时间的影响已得到广泛研究。然而，到目前为止，还没有关于T1弛豫率（r1）如何受到NaGdF 4结晶的不同多晶型（立方（α）和六方（β））影响的报道。在这里，微波辅助的热分解方法的开发，赠款选择性访问的NaGdF 4纳米粒子的任一相在相同的尺寸范围内，允许主机结晶度的影响，对r1进行调查。结果发现，在3 T立方NaGdF 4纳米粒子表现出较大的r1值比他们的六方类似物。这一结果被解释的基础上Solomon-Bloembergen-Morgan理论，表明内球的贡献r1是更明显的立方NaGdF 4纳米粒子相比，他们的六边形对应物。无论选择的表面改性如何，即小柠檬酸酯基团或长链聚（丙烯酸），这都是正确的。关键方面被发现是一个多晶型诱导较大的流体动力学直径和较高的磁化强度所拥有的立方纳米粒子。
Sodium gadolinium fluoride (NaGdF4) nanoparticles are promising candidates as T1 shortening magnetic resonance imaging (MRI) contrast agents due to the paramagnetic properties of the Gd3+ ion. Effects of size and surface modification of these nanoparticles on proton relaxation times have been widely studied. However, to date, there has been no report on how T1 relaxivity (r1) is affected by the different polymorphs in which NaGdF4 crystallizes: cubic (α) and hexagonal (β). Here, a microwave-assisted thermal decomposition method was developed that grants selective access to NaGdF4 nanoparticles of either phase in the same size range, allowing the influence of host crystallinity on r1 to be investigated. It was found that at 3 T cubic NaGdF4 nanoparticles exhibit larger r1 values than their hexagonal analogues. This result was interpreted based on Solomon-Bloembergen-Morgan theory, suggesting that the inner sphere contribution to r1 is more pronounced for cubic NaGdF4 nanoparticles as compared to their hexagonal counterparts. This holds true irrespective of the chosen surface modification, i.e. small citrate groups or longer chain poly(acrylic acid). Key aspects were found to be a polymorph-induced larger hydrodynamic diameter and the higher magnetization possessed by cubic nanoparticles.