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Validation of Inner, Second, and Outer Sphere Contributions to T1 and T2 Relaxation in Gd3+-Based Nanoparticles Using Eu3+ Lifetime Decay as a Probe
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2018-05-09 00:00:00 , DOI: 10.1021/acs.jpcc.8b02807 Armita Dash 1, 2 , Barbara Blasiak 3, 4 , Boguslaw Tomanek 3, 4, 5 , Frank C. J. M. van Veggel 1, 2
The Journal of Physical Chemistry C ( IF 3.3 ) Pub Date : 2018-05-09 00:00:00 , DOI: 10.1021/acs.jpcc.8b02807 Armita Dash 1, 2 , Barbara Blasiak 3, 4 , Boguslaw Tomanek 3, 4, 5 , Frank C. J. M. van Veggel 1, 2
Affiliation
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Paramagnetic lanthanide-based NPs are currently designed as magnetic resonance imaging (MRI) contrast agents to obtain optimal relaxivities at high magnetic fields of 7, 9.4, and 11.7 T where human imaging has been possible yielding high contrast to noise ratio in the MR images compared to the clinical field of 3 T. However, the underlying longitudinal (T1) and transverse (T2) relaxation mechanisms of the NP-based contrast agents based on the spatial motion and proximity of water protons with respect to the paramagnetic ions on the surface of NPs are still not well understood, specifically, in terms of contributions from inner, second, and outer spheres of coordination of water molecules to the NPs. Gd3+-based NPs, e.g., NaGdF4, are promising T1 contrast agents owing to the paramagnetic Gd3+ possessing a symmetric 8S7/2-state and slow electronic relaxation relevant to its efficiency to produce a positive (T1) contrast. Here, water-dispersed NaGdF4:Eu3+ (3 nm diameter, TEM) and NaYF4–NaGdF4:Eu3+ core–shell NPs (18.3 nm core diameter with 0.5 nm thick shell, TEM) were studied for their r1 and r2 relaxivities at 9.4 T. Excited state lifetime decays of Eu3+ dopants, which are highly sensitive to proximate water molecules, were analyzed, demonstrating a dominance of inner and second sphere contribution over outer sphere to the T1 and T2 relaxations in smaller NaGdF4:Eu3+ NPs while exclusively outer sphere in NaYF4–NaGdF4:Eu3+ core–shell NPs.
中文翻译：
Eu 3+寿命衰变作为探针验证基于Gd 3+的纳米粒子对T 1和T 2弛豫的内，第二和外层贡献
目前，基于顺磁性镧系元素的NP被设计为磁共振成像（MRI）造影剂，以便在7、9.4和11.7 T的高磁场下获得最佳弛豫度，而在这种情况下，人类成像可能会在MR图像中产生高对比度的噪声比。到3 T的临床领域。但是，基于水质子相对于顺磁性离子在质子上的空间运动和接近度，基于NP的造影剂的基本纵向（T 1）和横向（T 2）弛豫机理。 NP的表面仍然没有被很好地理解，特别是在水分子配位的内，第二和外球对NP的贡献方面。基于Gd 3+的NP，例如NaGdF 4由于顺磁性Gd 3+具有对称的8 S 7/2状态和缓慢的电子弛豫（与其产生正（T 1）对比度的效率有关），因此是有希望的T 1造影剂。在这里，研究了水分散的NaGdF 4：Eu 3+（直径3 nm，TEM）和NaYF 4 –NaGdF 4：Eu 3+核-壳NPs（18.3 nm核直径和0.5 nm厚壳，TEM）的r 1和r 2在9.4 T时的弛豫。Eu3 +的激发态寿命衰变分析了对邻近水分子高度敏感的掺杂剂，证明了较小的NaGdF 4：Eu 3+ NP中内层和第二层球对外层球体的T 1和T 2弛豫的支配力，而在NaYF 4中仅外层球体–NaGdF 4：Eu 3+核-壳NP。
更新日期：2018-05-09
中文翻译：
Eu 3+寿命衰变作为探针验证基于Gd 3+的纳米粒子对T 1和T 2弛豫的内，第二和外层贡献
目前，基于顺磁性镧系元素的NP被设计为磁共振成像（MRI）造影剂，以便在7、9.4和11.7 T的高磁场下获得最佳弛豫度，而在这种情况下，人类成像可能会在MR图像中产生高对比度的噪声比。到3 T的临床领域。但是，基于水质子相对于顺磁性离子在质子上的空间运动和接近度，基于NP的造影剂的基本纵向（T 1）和横向（T 2）弛豫机理。 NP的表面仍然没有被很好地理解，特别是在水分子配位的内，第二和外球对NP的贡献方面。基于Gd 3+的NP，例如NaGdF 4由于顺磁性Gd 3+具有对称的8 S 7/2状态和缓慢的电子弛豫（与其产生正（T 1）对比度的效率有关），因此是有希望的T 1造影剂。在这里，研究了水分散的NaGdF 4：Eu 3+（直径3 nm，TEM）和NaYF 4 –NaGdF 4：Eu 3+核-壳NPs（18.3 nm核直径和0.5 nm厚壳，TEM）的r 1和r 2在9.4 T时的弛豫。Eu3 +的激发态寿命衰变分析了对邻近水分子高度敏感的掺杂剂，证明了较小的NaGdF 4：Eu 3+ NP中内层和第二层球对外层球体的T 1和T 2弛豫的支配力，而在NaYF 4中仅外层球体–NaGdF 4：Eu 3+核-壳NP。
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