title: High-resolution length sorting and purification of DNA-wrapped carbon nanotubes by size-exclusion chromatography.
abstract: We report a size-exclusion chromatography (SEC) process to purify DNA-wrapped carbon nanotubes (DNA-CNT) and to sort them into fractions of uniform length. A type of silica-based column resin was identified that shows minimum adsorption of DNA-CNT. Three such columns in series with pore sizes of 2000, 1000, and 300 A were found to separate DNA-CNT into fractions of very narrow length distribution, as measured directly by atomic force microscopy. The average length decreases monotonically from > 500 nm in the early fractions to < 100 nm in the late fractions, with length variation < or = 10% in each of the measured fractions. Using UV-vis-NIR spectroscopy, we showed that SEC is very effective in removing graphitic impurities that contribute to the spectral baseline and a broad absorption peak at approximately 270 nm. This result highlights the importance of CNT purification in the study of optical properties of CNT.
authors.affiliation: Sepax Technologies, Inc., Newark, Delaware 19711, USA.
authors.forename: Xueying
authors.initials: X
authors.lastname: Huang
authors.forename: Robert S
authors.initials: RS
authors.lastname: Mclean
authors.forename: Ming
authors.initials: M
authors.lastname: Zheng
mesh_terms: D002850:Chromatography, Gel / Q000379:methods*; D004247:DNA / Q000737:chemistry* / Q000302:isolation & purification*; D018625:Microscopy, Atomic Force; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis
chemical_list: D037742:Nanotubes, Carbon; D004247:DNA