Functional Analysis of Liposomes Containing Single-Walled Carbon Nanotubes (SWNTs) by Fluorescence Microscopy

Abstract

Single-walled carbon nanotubes (SWNTs) are hollow cylinder-shaped carbon materials through which ions and some small molecules can pass with high permeability. Hence, SWNTs have attracted great interest for their potential application in spherical artificial biomembranes (liposomes) used to filter substances. Mass transport processes through SWNTs are currently measured based on changes in the fluorescence intensity of fluorescent probes in liposomes. However, it is difficult to determine whether the change in fluorescence intensity is due to SWNTs or to destruction of the liposome in small liposomes (<200 nm diameter). Accordingly, the mechanism of the transport process remains unclear. Therefore, in this study, we propose a new approach to observing the transport process through SWNTs by embedding SWNTs in liposomes over 10 µm in diameter (giant liposomes). The large size of the liposomes allows easy observation of their shape under a microscope. The experimental results indicate that the ion permeation and transport processes of SWNTs can be indirectly observed using giant liposomes and a fluorescence microscope.