GREMAN, UMR CNRS 7347, Université de Tours, 37200, Tours, France.
National University of Science and Technology «MISiS», 119049, Moscow, Russian Federation.
J Nanobiotechnology. 2019 Feb 6;17(1):27. doi: 10.1186/s12951-019-0463-5.
Theranostics application of superparamagnetic nanoparticles based on magnetite and maghemite is impeded by their toxicity. The use of additional protective shells significantly reduced the magnetic properties of the nanoparticles. Therefore, iron carbides and pure iron nanoparticles coated with multiple layers of onion-like carbon sheath seem to be optimal for biomedicine. Fluorescent markers associated with magnetic nanoparticles provide reliable means for their multimodal visualization. Here, biocompatibility of iron nanoparticles coated with graphite-like shell and labeled with Alexa 647 fluorescent marker has been investigated.
Iron core nanoparticles with intact carbon shells were purified by magnetoseparation after hydrochloric acid treatment. The structure of the NPs (nanoparticles) was examined with a high resolution electron microscopy. The surface of the NPs was alkylcarboxylated and further aminated for covalent linking with Alexa Fluor 647 fluorochrome to produce modified fluorescent magnetic nanoparticles (MFMNPs). Live fluorescent imaging and correlative light-electron microscopy were used to study the NPs intracellular distribution and the effects of constant magnetic field on internalized NPs in the cell culture were analyzed. Cell viability was assayed by measuring a proliferative pool with Click-IT labeling.
The microstructure and magnetic properties of superparamagnetic Fe@C core-shell NPs as well as their endocytosis by living tumor cells, and behavior inside the cells in constant magnetic field (150 mT) were studied. Correlative light-electron microscopy demonstrated that NPs retained their microstructure after internalization by the living cells. Application of constant magnetic field caused orientation of internalized NPs along power lines thus demonstrating their magnetocontrollability. Carbon onion-like shells make these NPs biocompatible and enable long-term observation with confocal microscope. It was found that iron core of NPs shows no toxic effect on the cell physiology, does not inhibit the cell proliferation and also does not induce apoptosis.
Non-toxic, biologically compatible superparamagnetic fluorescent MFMNPs can be further used for biological application such as delivery of biologically active compounds both inside the cell and inside the whole organism, magnetic separation, and magnetic resonance imaging (MRI) diagnostics.
基于磁铁矿和磁赤铁矿的超顺磁纳米粒子的治疗诊断应用受到其毒性的阻碍。使用额外的保护层会显著降低纳米粒子的磁性。因此，碳化铁和多层洋葱状碳壳包裹的纯铁纳米粒子似乎是生物医学的最佳选择。与磁性纳米粒子结合的荧光标记物为其多模式可视化提供了可靠的手段。在这里，研究了涂有石墨状壳并标记有 Alexa 647 荧光标记物的铁纳米粒子的生物相容性。
用盐酸处理后，通过磁分离对具有完整碳壳的铁核纳米粒子进行纯化。用高分辨率电子显微镜检查 NPs（纳米粒子）的结构。NPs 的表面经烷基羧化，进一步氨化，与 Alexa Fluor 647 荧光染料共价连接，制得修饰后的荧光磁性纳米粒子（MFMNPs）。活细胞荧光成像和相关的光电子显微镜用于研究 NPs 的细胞内分布，并分析恒磁场对细胞培养中内化 NPs 的影响。通过 Click-IT 标记测量增殖池来测定细胞活力。
研究了超顺磁 Fe@C 核壳 NPs 的微观结构和磁性，以及它们被活肿瘤细胞内吞作用，以及在恒磁场（150 mT）内细胞内的行为。相关的光电子显微镜显示，NP 被活细胞内化后保留了其微观结构。施加恒磁场会导致内化的 NPs 沿着电源线取向，从而证明了它们的磁控能力。洋葱状的碳壳使这些 NPs 具有生物相容性，并能够在共聚焦显微镜下进行长期观察。研究发现，NP 的铁核对细胞生理没有毒性作用，不会抑制细胞增殖，也不会诱导细胞凋亡。
无毒、生物相容的超顺磁荧光 MFMNPs 可进一步用于生物应用，如在细胞内和整个生物体内部输送生物活性化合物、磁性分离和磁共振成像（MRI）诊断。
