在Fe L-边缘处具有功能化纳米颗粒的相关细胞重叠图
Correlative cellular ptychography with functionalized nanoparticles at the Fe L-edge
摘要：
纳米粒子在细胞内的精确定位对于理解细胞-粒子相互作用至关重要，并且在纳米医学中具有广泛的应用。在这里，我们报告了一个证明的原则实验成像个别功能化纳米粒子在哺乳动物细胞内的相关显微镜。使用化学固定的，用荧光核-壳纳米颗粒标记的HeLa细胞作为模型系统，我们实现了氧化石墨烯层作为基底，以显着减少背景散射。我们确定感兴趣的细胞功能的荧光显微镜，然后扫描透射X射线断层扫描定位的颗粒在3D中，并ptychographic相干衍射成像的精细功能在该地区的高分辨率。通过将X射线能量调整到Fe L-边缘，我们证明了对由25 nm厚的荧光二氧化硅（SiO2）壳包裹的22 nm磁性Fe 3 O 4核组成的纳米颗粒的灵敏检测。这些荧光核-壳纳米颗粒作为地标，并在细胞环境中提供清晰度。我们的相关显微镜结果证实了一个子集的颗粒被完全内化，高对比度的重叠图像显示了两个氧化态的个别纳米粒子的分辨率为16.5 nm。在哺乳动物细胞内精确定位单个荧光纳米颗粒的能力将扩大我们对功能化纳米颗粒的结构/功能关系的理解。
英文摘要：
Precise localization of nanoparticles within a cell is crucial to the understanding of cell-particle interactions and has broad applications in nanomedicine. Here, we report a proof-of-principle experiment for imaging individual functionalized nanoparticles within a mammalian cell by correlative microscopy. Using a chemically-fixed, HeLa cell labeled with fluorescent core-shell nanoparticles as a model system, we implemented a graphene-oxide layer as a substrate to significantly reduce background scattering. We identified cellular features of interest by fluorescence microscopy, followed by scanning transmission X-ray tomography to localize the particles in 3D, and ptychographic coherent diffractive imaging of the fine features in the region at high resolution. By tuning the X-ray energy to the Fe L-edge, we demonstrated sensitive detection of nanoparticles composed of a 22 nm magnetic Fe3O4 core encased by a 25-nm-thick fluorescent silica (SiO2) shell. These fluorescent core-shell nanoparticles act as landmarks and offer clarity in a cellular context. Our correlative microscopy results confirmed a subset of particles to be fully internalized, and high-contrast ptychographic images showed two oxidation states of individual nanoparticles with a resolution of ~16.5 nm. The ability to precisely localize individual fluorescent nanoparticles within mammalian cells will expand our understanding of the structure/function relationships for functionalized nanoparticles.
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