Tube length and cell type-dependent cellular responses to ultra-short single-walled carbon nanotube.

This paper presents a detailed study on the cellular responses to PEGylated ultra-short (<80 nm) single-walled carbon nanotube (US-SWNT). The experimental results show clearly the tube length and cell-type dependent cellular uptake, intracellular localization, excretion of US-SWNT, as well as US-SWNT partitioning at cell division. Confocal fluorescence imaging and flow cytometry analysis of three cell types (HeLa, human hepatoma, and HUVEC) indicate that PEGylated SWNT below 35 nm might not be suitable for active targeting but could find alternative applications in gene transfection due to the ability to spontaneously traverse the nuclear membrane. While US-SWNT with an average length of 30 nm were rapidly excreted by non-polarized HeLa and hepatoma cells, lysosomal retention was observed by HUVEC, a polarized cell line. Further, HUVEC transferred intracellular US-SWNT to subsequent generations through asymmetric partitioning. These results could have significant implications for the rational design of SWNT carriers for drug delivery, as contrast agents, and for other new niche applications.