RESUMO
The mechanical response of the cytoplasm was investigated by the intracellular implantation of magnetic nanorods and exposure to low-frequency rotatory magnetic fields. Nanorods (Pt-Ni, â¼200 nm diameter) fabricated by electrodeposition in templates of porous alumina with lengths of approximately 2 and 5 µm were inserted into NIH/3T3 fibroblasts and manipulated with a rotational magnetic field. Nanorod rotation was observed only for torques greater than 3.0 × 10(-16) Nm, suggesting a Bingham-type behavior of the cytoplasm. Higher torques produced considerable deformation of the intracellular material. The cell nucleus and cell membrane were significantly deformed by nanorods actuated by 4.5 × 10(-15) Nm torques. Our results demonstrate that nanorods under magnetic fields are an effective tool to mechanically probe the intracellular environment. We envision that our findings may contribute to the noninvasive and direct mechanical characterization of the cytoplasm.
Assuntos
Óxido de Alumínio , Núcleo Celular/metabolismo , Citoplasma/metabolismo , Fibroblastos/metabolismo , Fenômenos Magnéticos , Nanotubos , Animais , Fibroblastos/citologia , Camundongos , Células NIH 3T3 , PorosidadeRESUMO
The organization of chromatin in the cell nucleus is crucial for gene expression regulation. However, physically probing the nuclear interior is challenging because high forces have to be applied using minimally invasive techniques. Here, magnetic nanorods embedded in the nucleus of living cells are subjected to controlled rotational forces, producing micron-sized displacements in the nuclear interior. The resulting time-dependent rotation of the nanorods is analyzed in terms of viscoelastic parameters of the nucleus, in wild-type and Lamin A/C deficient cells. This method and analysis reveal that Lamin A/C knockout, together perhaps with other changes that result from the knockout, induce significant decreases in the nuclear viscosity and elasticity.