查看文章

New materials for the intracellular transport of biological cargos such as DNA, proteins, and drug molecules have been actively sought to effectively breach the cell-membrane barriers for delivery and enabling functionality of extracellular agents. Single-walled carbon nanotubes (SWNT) have been recently shown to shuttle various molecular cargos inside living cells including proteins, short peptides, and nucleic acids.[1–8] The internalized nanotubes were found to be biocompatible and nontoxic at the cellular level. Furthermore, a very recent study has established targeted internalization of SWNTs into cancer cells that express specific cellsurface receptors and subsequent use as high near-infrared (NIR) absorbing agents for cancer-cell destruction without harming normal cells.[7] Release of oligodeoxynucleotides from SWNT transporters in vitro has also been demonstrated by NIR excitation of nanotubes that are located inside living cells. The utilization of the intrinsic physical properties of SWNTs allows the realization of a new class of biotransporters and opens up new possibilities in drug delivery and NIR radiation therapy.

At the present time, several fundamental issues remain to be addressed for the use of carbon nanotubes as potential biological transporters. One such issue is the entry mechanism that regulates the cellular internalization of SWNTs and their cargos. We [1, 2] have suggested that SWNTs traverse the cellular membrane through endocytosis, whereas Pantarotto et al.[5] have suggested an energy independent nonendocytotic mechanism that involves insertion and diffusion of nanotubes through the lipid bilayer of the cell …