Department of Nano Biophotonics, Institute of Photonic Technology, Jena, Germany.
Nanotechnology. 2011 Jul 1;22(26):265102. doi: 10.1088/0957-4484/22/26/265102. Epub 2011 May 17.
When using magnetic nanoparticles as a heating source for magnetic particle hyperthermia it is of particular interest to know if the particles are free to move in the interstitial fluid or are fixed to the tumour tissue. The immobilization state determines the relaxation behaviour of the administered particles and thus their specific heating power. To investigate this behaviour, magnetic multicore nanoparticles were injected into experimentally grown tumours in mice and magnetic heating treatment was carried out in an alternating magnetic field (H = 25 kA m(-1), f = 400 kHz). The tested particles were well suited for magnetic heating treatment as they heated a tumour of about 100 mg by about 22 K within the first 60 s. Upon sacrifice, histological tumour examination showed that the particles form spots in the tissue with a mainly homogeneous particle distribution in these spots. The magnetic ex vivo characterization of the removed tumour tissue gave clear evidence for the immobilization of the particles in the tumour tissue because the particles in the tumour showed the same magnetic behaviour as immobilized particles. Therefore, the particles are not able to rotate and a temperature increase due to Brown relaxation can be neglected. To accurately estimate the heating potential of magnetic materials, the respective environments influencing the nanoparticle mobility status have to be taken into account.
当使用磁性纳米粒子作为磁粒子热疗的热源时，特别感兴趣的是要知道粒子是否可以在间质液中自由移动，或者是否固定在肿瘤组织上。固定状态决定了所施用的粒子的弛豫行为，从而决定了它们的特定加热功率。为了研究这种行为，将磁性多核纳米粒子注入到小鼠实验性生长的肿瘤中，并在交变磁场中（H = 25 kA m（-1），f = 400 kHz）进行磁加热处理。测试的粒子非常适合于磁加热处理，因为它们在最初的 60 秒内将约 100 毫克的肿瘤加热了约 22 K。牺牲后，组织学肿瘤检查表明，粒子在组织中形成斑点，这些斑点中的粒子分布主要均匀。从切除的肿瘤组织的体外磁性表征中可以清楚地证明粒子在肿瘤组织中的固定化，因为肿瘤中的粒子表现出与固定化粒子相同的磁性行为。因此，粒子不能旋转，并且由于布朗弛豫引起的温度升高可以忽略不计。为了准确估计磁性材料的加热潜力，必须考虑影响纳米粒子迁移状态的相应环境。
