Size exclusion chromatography-based length sorting of single-walled carbon nanotubes stably coated with cross-linked polymers

Abstract

The stable dispersion of individual single-walled carbon nanotubes (SWCNTs) in solutions is a primary requisite for various applications, especially when their unique near-infrared (NIR) fluorescence is utilized. Coating SWCNTs with cross-linked polymers (e.g., gels) can result in highly stable dispersions due to the thin gel layer that acts as an undetachable dispersant. One attractive feature of gel-coating is the design flexibility of the gel; for example, post-modifications and bioapplications are possible when reactive sites and PEG units are introduced, respectively. In this study, gel-coated SWCNTs are length-sorted using size exclusion chromatography (SEC), wherein the gel layer consists of PEG-containing gel with reactive sites. Due to the high dispersion stability of the gel coating, SEC-based length sorting is achievable without adding any dispersants in the mobile phase. The length-sorted SWCNTs obtained in this manner maintain their strong NIR fluorescence and undergo post-modification with proteins, both of which are practical for biological applications.