title: DNA sequence motifs for structure-specific recognition and separation of carbon nanotubes.
abstract: Single-walled carbon nanotubes (SWNTs) are a family of molecules that have the same cylindrical shape but different chiralities. Many fundamental studies and technological applications of SWNTs require a population of tubes with identical chirality that current syntheses cannot provide. The SWNT sorting problem-that is, separation of a synthetic mixture of tubes into individual single-chirality components-has attracted considerable attention in recent years. Intense efforts so far have focused largely on, and resulted in solutions for, a weaker version of the sorting problem: metal/semiconductor separation. A systematic and general method to purify each and every single-chirality species of the same electronic type from the synthetic mixture of SWNTs is highly desirable, but the task has proven to be insurmountable to date. Here we report such a method, which allows purification of all 12 major single-chirality semiconducting species from a synthetic mixture, with sufficient yield for both fundamental studies and application development. We have designed an effective search of a DNA library of approximately 10(60) in size, and have identified more than 20 short DNA sequences, each of which recognizes and enables chromatographic purification of a particular nanotube species from the synthetic mixture. Recognition sequences exhibit a periodic purine-pyrimidines pattern, which can undergo hydrogen-bonding to form a two-dimensional sheet, and fold selectively on nanotubes into a well-ordered three-dimensional barrel. We propose that the ordered two-dimensional sheet and three-dimensional barrel provide the structural basis for the observed DNA recognition of SWNTs.
authors: DuPont Central Research and Development, Wilmington, Delaware 19880, USA.
authors: Xiaomin
authors: X
authors: Tu
authors: Suresh
authors: S
authors: Manohar
authors: Anand
authors: A
authors: Jagota
authors: Ming
authors: M
authors: Zheng
mesh_terms: D001483:Base Sequence; D005591:Chemical Fractionation / Q000379:methods*; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D015723:Gene Library; D008958:Models, Molecular; D037742:Nanotubes, Carbon / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D012680:Sensitivity and Specificity; D013053:Spectrophotometry; D013379:Substrate Specificity
chemical_list: D037742:Nanotubes, Carbon; D004247:DNA