Department of Chemical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.
J Nanobiotechnology. 2011 Sep 30;9:45. doi: 10.1186/1477-3155-9-45.
Carbon nanotubes are increasingly being tested for use in cellular applications. Determining the mode of entry is essential to control and regulate specific interactions with cells, to understand toxicological effects of nanotubes, and to develop nanotube-based cellular technologies. We investigated cellular uptake of Pluronic copolymer-stabilized, purified ~145 nm long single wall carbon nanotubes (SWCNTs) through a series of complementary cellular, cell-mimetic, and in vitro model membrane experiments.
SWCNTs localized within fluorescently labeled endosomes, and confocal Raman spectroscopy showed a dramatic reduction in SWCNT uptake into cells at 4°C compared with 37°C. These data suggest energy-dependent endocytosis, as shown previously. We also examined the possibility for non-specific physical penetration of SWCNTs through the plasma membrane. Electrochemical impedance spectroscopy and Langmuir monolayer film balance measurements showed that Pluronic-stabilized SWCNTs associated with membranes but did not possess sufficient insertion energy to penetrate through the membrane. SWCNTs associated with vesicles made from plasma membranes but did not rupture the vesicles.
These measurements, combined, demonstrate that Pluronic-stabilized SWCNTs only enter cells via energy-dependent endocytosis, and association of SWCNTs to membrane likely increases uptake.
碳纳米管越来越多地被应用于细胞研究。确定进入细胞的方式对于控制和调节与细胞的特定相互作用、了解纳米管的毒理学效应以及开发基于纳米管的细胞技术至关重要。我们通过一系列互补的细胞、类细胞和体外模型膜实验，研究了多臂嵌段共聚物稳定的、纯化的~145nm 长单壁碳纳米管（SWCNTs）的细胞摄取。
SWCNTs 定位于荧光标记的内体中，共聚焦拉曼光谱显示，与 37°C 相比，SWCNT 在 4°C 下进入细胞的摄取量明显减少。这些数据表明存在能量依赖的内吞作用，如先前所示。我们还研究了 SWCNTs 通过质膜进行非特异性物理渗透的可能性。电化学阻抗谱和 Langmuir 单层膜天平测量表明，多臂嵌段共聚物稳定的 SWCNTs 与膜结合，但不具有足够的插入能量穿透膜。SWCNTs 与由质膜制成的囊泡结合，但不破坏囊泡。
这些测量结果表明，多臂嵌段共聚物稳定的 SWCNTs 仅通过能量依赖的内吞作用进入细胞，并且 SWCNTs 与膜的结合可能会增加摄取。
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