Efficient isolation and solubilization of pristine single-walled nanotubes in bile salt micelles

We have investigated a wide variety of surfactants for their efficiency in dissolving isolated single-walled carbon nanotubes (SWNTs) in water. In doing so, we have completely avoided the harsh chemical or mechanical conditions, such as acid or ultrasonic treatments, that are known to damage SWNTs. Bile salts in particular are found to be exceptionally effective in dissolving individual tubes, as evidenced by highly resolved optical absorption spectra, bright bandgap fluorescence, and the unprecedented resolution (similar to2.5 cm(-1)) of the radial breathing modes in Raman spectra. This is attributed to the formation of very regular and stable micelles around the nanotubes providing an unusually homogenous environment. Quantitative information concerning the degree of solubilization is obtained from absorption spectroscopy.