Lin Min, Breukels Vincent, Scheenen Tom W J, Paulusse Jos M J
Department of Biomolecular Nanotechnology, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Department of Medical Imaging, Radboud University Medical Center, Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands.
ACS Appl Mater Interfaces. 2021 Jul 7;13(26):30835-30843. doi: 10.1021/acsami.1c07156. Epub 2021 Jun 25.
Two dominant crystalline phases of silicon carbide (SiC): α-SiC and β-SiC, differing in size and chemical composition, were investigated regarding their potential for dynamic nuclear polarization (DNP). Si nuclei in α-SiC micro- and nanoparticles with sizes ranging from 650 nm to 2.2 μm and minimal oxidation were successfully hyperpolarized without the use of free radicals, while β-SiC samples did not display appreciable degrees of polarization under the same polarization conditions. Long relaxation times in α-SiC of up to 1600 s (∼27 min) were recorded for the Si nuclei after 1 h of polarization at a temperature of 4 K. Interestingly, these promising α-SiC particles allowed for direct hyperpolarization of both Si and C nuclei, resulting in comparably strong signal amplifications. Moreover, the relaxation time of C nuclei in 750 nm-sized α-SiC particles was over 33 min, which far exceeds times of conventional C DNP probes with values in the order of 1-2 min. The present work demonstrates the feasibility of DNP on SiC micro- and nanoparticles and highlights their potential as hyperpolarized magnetic resonance imaging agents.
研究了碳化硅（SiC）的两种主要晶相：α-SiC和β-SiC，它们在尺寸和化学成分上存在差异，探讨了它们用于动态核极化（DNP）的潜力。尺寸范围为650纳米至2.2微米且氧化程度最低的α-SiC微米和纳米颗粒中的硅原子核在不使用自由基的情况下成功实现了超极化，而β-SiC样品在相同的极化条件下未表现出可观的极化程度。在4 K温度下极化1小时后，α-SiC中硅原子核的弛豫时间长达1600秒（约27分钟）。有趣的是，这些有前景的α-SiC颗粒能够使硅和碳原子核直接超极化，从而产生相当强的信号放大。此外，750纳米尺寸的α-SiC颗粒中碳原子核的弛豫时间超过33分钟，远远超过传统碳DNP探针约1 - 2分钟的弛豫时间。本工作证明了在SiC微米和纳米颗粒上进行DNP的可行性，并突出了它们作为超极化磁共振成像剂的潜力。
