Physik Department E21, Technische Universität München, D-85747 Garching, Germany; Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, D-85747 Garching, Germany.
Peter Grünberg Institute (PGI-5) and Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons, Research Centre Jülich, D-52425 Jülich, Germany.
J Control Release. 2015 Jan 10;197:131-7. doi: 10.1016/j.jconrel.2014.11.007. Epub 2014 Nov 11.
Magnetic nanoparticles are highly desirable for biomedical research and treatment of cancer especially when combined with hyperthermia. The efficacy of nanoparticle-based therapies could be improved by generating radioactive nanoparticles with a convenient decay time and which simultaneously have the capability to be used for locally confined heating. The core-shell morphology of such novel nanoparticles presented in this work involves a polysilico-tungstate molecule of the polyoxometalate family as a precursor coating material, which transforms into an amorphous tungsten oxide coating upon annealing of the FePt core-shell nanoparticles. The content of tungsten atoms in the nanoparticle shell is neutron activated using cold neutrons at the Heinz Maier-Leibnitz (FRMII) neutron facility and thereby transformed into the radioisotope W-187. The sizeable natural abundance of 28% for the W-186 precursor isotope, a radiopharmaceutically advantageous gamma-beta ratio of γβ≈30% and a range of approximately 1mm in biological tissue for the 1.3MeV β-radiation are promising features of the nanoparticles' potential for cancer therapy. Moreover, a high temperature annealing treatment enhances the magnetic moment of nanoparticles in such a way that a magnetic heating effect of several degrees Celsius in liquid suspension - a prerequisite for hyperthermia treatment of cancer - was observed. A rise in temperature of approximately 3°C in aqueous suspension is shown for a moderate nanoparticle concentration of 0.5mg/ml after 15min in an 831kHz high-frequency alternating magnetic field of 250Gauss field strength (25mT). The biocompatibility based on a low cytotoxicity in the non-neutron-activated state in combination with the hydrophilic nature of the tungsten oxide shell makes the coated magnetic FePt nanoparticles ideal candidates for advanced radiopharmaceutical applications.
磁性纳米粒子在生物医学研究和癌症治疗中非常理想，尤其是与热疗结合使用时。通过生成放射性纳米粒子，可以提高基于纳米粒子的治疗效果，这些纳米粒子具有方便的衰减时间，并且同时具有用于局部限制加热的能力。本文提出的这种新型纳米粒子的核壳形态涉及多硅钨酸盐家族的多金属氧酸盐分子作为前体涂层材料，该材料在 FePt 核壳纳米粒子退火时转化为非晶态氧化钨涂层。通过在海因里希·迈尔-莱布尼兹（Heinz Maier-Leibnitz，FRMII）中子设施中使用冷中子对纳米粒子壳中的钨原子进行中子激活，从而将其转化为放射性同位素 W-187。W-186 前体同位素的丰度为 28%，放射性药物学上有利的γβ比γβ≈30%，以及在生物组织中的射程约为 1mm 的 1.3MeV β 辐射，这些都是纳米粒子在癌症治疗中具有潜力的有希望的特征。此外，高温退火处理以这样的方式增强纳米粒子的磁矩，即在液体悬浮液中观察到几度的磁热效应 - 这是癌症热疗的前提。在 831kHz 高频交变磁场中，磁场强度为 250Gauss（25mT），浓度为 0.5mg/ml 的适度纳米粒子在 15 分钟后，在水中悬浮液中的温度升高约 3°C。在未进行中子激活的状态下具有低细胞毒性的生物相容性，再加上氧化钨壳的亲水性，使得涂覆的磁性 FePt 纳米粒子成为先进放射性药物应用的理想候选物。
