Osipov Vladimir Yu, Boukhvalov Danil W, Takai Kazuyuki
Ioffe Institute, Polytechnicheskaya 26, St.-Petersburg 194021, Russia.
Institute of Materials Physics and Chemistry, College of Science, Nanjing Forestry University, Nanjing 210037, China.
Nanomaterials (Basel). 2023 Jul 1;13(13):1995. doi: 10.3390/nano13131995.
The magnetic characteristics of a system of triply charged gadolinium ions Gd chelated with carboxyls on the surface of detonation nanodiamond (DND) particles have been studied. Gd ions demonstrate almost perfect spin (S = 7/2) paramagnetism with negligible antiferromagnetic interaction between spins (Weiss temperature about -0.35 K) for a wide range of concentrations up to ~18 ions per 5 nm particle. The study of the concentration dependence of the electron paramagnetic resonance signal for DND intrinsic defects with spin ½ ( = 2.0027) shows that Gd ions are located on average at a distance of no more than 1.4 nm from shallow subsurface defects with spin /. At the same time, they are located (according to density functional theory calculations) at a distance of about or at least 0.28 nm from the particle surface. Magnetic studies also confirm the isolated nature of the gadolinium chelate complexes on the surface of DND particles. DND particles turn out to be an optimal carrier for high-spin ions (gadolinium) in a highly concentrated isolated state. This property makes DND-Gd particles a candidate for the role of a contrast agent for magnetic resonance imaging.
研究了与爆轰纳米金刚石（DND）颗粒表面羧基螯合的三价钆离子（Gd）体系的磁性。对于高达每5纳米颗粒约18个离子的广泛浓度范围，Gd离子表现出几乎完美的自旋（S = 7/2）顺磁性，自旋之间的反铁磁相互作用可忽略不计（魏斯温度约为-0.35 K）。对具有1/2自旋（g = 2.0027）的DND固有缺陷的电子顺磁共振信号的浓度依赖性研究表明，Gd离子平均位于距具有1/2自旋的浅表面下缺陷不超过1.4纳米的距离处。同时，根据密度泛函理论计算，它们位于距颗粒表面约0.28纳米或至少0.28纳米的距离处。磁性研究还证实了DND颗粒表面钆螯合物的孤立性质。DND颗粒被证明是处于高度浓缩孤立状态的高自旋离子（钆）的最佳载体。这一特性使DND-Gd颗粒成为磁共振成像造影剂的候选者。
