Use of gel electrophoresis and Raman spectroscopy to characterize the effect of the electronic structure of single-walled carbon nanotubes on cellular uptake.

It is well-known that the uptake of single-walled carbon nanotubes (SWNTs) by living cells depends on factors such as SWNT length and surface chemistry. Surprisingly, little is known about whether the electronic structure of a SWNT influences uptake. One reason for this has been the lack of methods to measure the uptake of SWNTs by cell populations. Previously, we developed a rapid, sensitive, and label-free sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE) method for measuring the amount of SWNTs in lysates prepared from cultured cells ( Wang et al. Anal. Chem. 2009 , 81 , 2944 ). Herein, we describe the use of SDS-PAGE and microprobe Raman spectroscopy to detect and distinguish the electronic structure of SWNTs internalized by mammalian cells. Using normal rat kidney (NRK) cells and SWNTs dispersed with bovine serum albumin (BSA), we demonstrate that the method can detect both metallic and semiconducting SWNTs in lysates of cells that had internalized BSA-SWNTs and that the uptake of BSA-SWNTs by NRK cells is not influenced by SWNT electronic structure.