Progress towards monodisperse single-walled carbon nanotubes

Nature Nanotechnology

Volumn 3, Issue 7, 2008, Pages 387-394

  Hersam, Mark C ^a  

^a Northwestern University   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CHROMATOGRAPHY; ELECTRONIC PROPERTIES; ELECTROPHORESIS; NANOTUBES; OPTICAL PROPERTIES; STEREOCHEMISTRY; YARN;

ELECTRICAL BREAKDOWN; ELECTRONIC AND OPTICAL PROPERTIES; METALLIC NANOTUBES; SELECTIVE GROWTH; SEMI-CONDUCTING NANOTUBES; SIZE DEPENDENCE; SYNTHETIC APPROACH; ULTRACENTRIFUGATION;

SINGLE-WALLED CARBON NANOTUBES (SWCN);

CARBON NANOTUBE; NANOMATERIAL; SINGLE WALLED NANOTUBE;

CHEMISTRY; CHROMATOGRAPHY; ELECTROPHORESIS; MATERIALS TESTING; MOLECULAR ELECTRONICS; NANOTECHNOLOGY; PRIORITY JOURNAL; REVIEW; SEMICONDUCTOR; ULTRACENTRIFUGATION;

EID: 46749136727     PISSN: 17483387     EISSN: 17483395     Source Type: Journal    
DOI: 10.1038/nnano.2008.135     Document Type: Review

References (122)

1. Thostenson, E. T., Ren, Z. F. & Chou, T. W. Advances in the science and technology of carbon nanotubes and their composites: A review. Compos. Sci. Technol. 61, 1899-1912 (2001).
2. Mahar, B., Laslau, C., Yip, R. & Sun, Y. Development of carbon nanotube-based sensors - A review. IEEE Sens. J. 7, 266-284 (2007).
3. Kaushik, B. K., Goel, S. & Rauthan, G. Future VLSI interconnects: optical fiber or carbon nanotube - a review. Microelectron. Int. 24, 53-63 (2007).
4. Avouris, P., Chen, Z. H. & Perebeinos, V. Carbon-based electronics. Nature Nanotech. 2, 605-615 (2007).
5. Charlier, J. C., Blase, X. & Roche, S. Electronic and transport properties of nanotubes. Rev. Mod. Phys. 79, 677-732 (2007).
6. Anantram, M. P. & Leonard, F. Physics of carbon nanotube electronic devices. Rep. Prog. Phys. 69, 507-561 (2006).
7. Ebbesen, T. W. & Ajayan, P. M. Large-scale synthesis of carbon nanotubes. Nature 358, 220-222 (1992).
8. Guo, T., Nikolaev, P., Thess, A., Colbert, D. T. & Smalley, R. E. Catalytic growth of single-walled nanotubes by laser vaporization. Chem. Phys. Lett. 243, 49-54 (1995).
9. Endo, M. et al. The production and structure of pyrolytic carbon nanotubes. J. Phys. Chem. Solids 54, 1841-1848 (1993).
10. Krupke, R. & Hennrich, F. Separation techniques for carbon nanotubes. Adv. Engineer. Mat. 7, 111-116 (2005).
11. Banerjee, S., Hemraj-Benny, T. & Wong, S. S. Routes towards separating metallic and semiconducting nanotubes. J. Nanosci. Nanotechnol. 5, 841-855 (2005).
12. Haddon, R. C., Sippel, J., Rinzler, A. G. & Papadimitrakopoulos, F. Purification and separation of carbon nanotubes. Mater. Res. Bull. 29, 252-259 (2004).
13. Ivchenko, E. L. & Spivak, B. Chirality effects in carbon nanotubes. Phys. Rev. B 66, 155404 (2002).
14. Arnold, M. S. Carbon Nanotubes: Photophysics, Biofunctionalization, and Sorting via Density Differentiation. PhD Thesis, Northwestern Univ. (2006).
15. Hirsch, A. Functionalization of single-walled carbon nanotubes. Angew. Chem. Int. Ed. 41, 1853-1859 (2002).
16. Banerjee, S., Hemraj-Benny, T. & Wong, S. S. Covalent surface chemistry of single-walled carbon nanotubes. Adv. Mat. 17, 17-29 (2005).
17. Tasis, D., Tagmatarchis, N., Bianco, A. & Prato, M. Chemistry of carbon nanotubes. Chem. Rev. 106, 1105-1136 (2006).
18. Campidelli, S., Meneghetti, M. & Prato, M. Separation of metallic and semiconducting single-walled carbon nanotubes via covalent functionalization. Small 3, 1672-1676 (2007).
19. Strano, M. S. et al. Electronic structure control of single-walled carbon nanotube functionalization. Science 301, 1519-1522 (2003).
20. Strano, M. S. Probing chiral selective reactions using a revised Kataura plot for the interpretation of single-walled carbon nanotube spectroscopy. J. Am. Chem. Soc. 125, 16148-16153 (2003).
21. Kim, W. J., Usrey, M. L. & Strano, M. S. Selective functionalization and free solution electrophoresis of single-walled carbon nanotubes: Separate enrichment of metallic and semiconducting SWNT. Chem. Mater. 19, 1571-1576 (2007).
22. Toyoda, S. et al. Separation of semiconducting single-walled carbon nanotubes by using a longalkyl-chain benzenediazonium compound. Chem. - Asian J. 2, 145-149 (2007).
23. An, L., Fu, Q. A., Lu, C. G. & Liu, J. A simple chemical route to selectively eliminate metallic carbon nanotubes in nanotube network devices. J. Am. Chem. Soc. 126, 10520-10521 (2004).
24. Balasubramanian, K., Sordan, R., Burghard, M. & Kern, K. A selective electrochemical approach to carbon nanotube field-effect transistors. Nano Lett. 4, 827-830 (2004).
25. Kamaras, K., Itkis, M. E., Hu, H., Zhao, B. & Haddon, R. C. Covalent bond formation to a carbon nanotube metal. Science 301, 1501-1501 (2003).
26. Hu, H. et al. Sidewall functionalization of single-walled carbon nanotubes by addition of dichlorocarbene. J. Am. Chem. Soc. 125, 14893-14900 (2003).
27. An, K. H. et al. A diameter-selective attack of metallic carbon nanotubes by nitronium ions. J. Am. Chem. Soc. 127, 5196-5203 (2005).
28. Yang, C. M. et al. Selective removal of metallic single-walled carbon nanotubes with small diameters by using nitric and sulfuric acids. J. Phys. Chem. B 109, 19242-19248 (2005).
29. An, K. H. et al. A diameter-selective chiral separation of single-wall carbon nanotubes using nitronium ions. J. Electron. Mater. 35, 235-242 (2006).
30. Ramesh, S. et al. Diameter selection of single-walled carbon nanotubes through programmable solvation in binary sulfonic acid mixtures. J. Phys. Chem. C 111, 17827-17834 (2007).
31. Banerjee, S. & Wong, S. S. Demonstration of diameter-selective reactivity in the sidewall ozonation of SWNTs by resonance Raman spectroscopy. Nano Lett. 4, 1445-1450 (2004).
32. Banerjee, S. & Wong, S. S. Selective metallic tube reactivity in the solution-phase osmylation of single-walled carbon nanotubes. J. Am. Chem. Soc. 126, 2073-2081 (2004).
33. Yudasaka, M., Zhang, M. & Iijima, S. Diameter-selective removal of single-wall carbon nanotubes through light-assisted oxidation. Chem. Phys. Lett. 374, 132-136 (2003).
34. Miyata, Y., Maniwa, Y. & Kataura, H. Selective oxidation of semiconducting single-wall carbon nanotubes by hydrogen peroxide. J. Phys. Chem. B 110, 25-29 (2006).
35. Lu, J. et al. Why semiconducting single-walled carbon nanotubes are separated from their metallic counterparts. Small 3, 1566-1576 (2007).
36. Menard-Moyon, C., Izard, N., Doris, E. & Mioskowski, C. Separation of semiconducting from metallic carbon nanotubes by selective functionalization with azomethine ylides. J. Am. Chem. Soc. 128, 6552-6553 (2006).
37. Maeda, Y. et al. Large-scale separation of metallic and semiconducting single-walled carbon nanotubes. J. Am. Chem. Soc. 127, 10287-10290 (2005).
38. Maeda, Y. et al. Dispersion and separation of small-diameter single-walled carbon nanotubes. J. Am. Chem. Soc. 128, 12239-12242 (2006).
39. Chattopadhyay, D., Galeska, L. & Papadimitrakopoulos, F. A route for bulk separation of semiconducting from metallic single-wall carbon nanotubes. J. Am. Chem. Soc. 125, 3370-3375 (2003).
40. Samsonidze, G. G. et al. Quantitative evaluation of the octadecylamine-assisted bulk separation of semiconducting and metallic single-wall carbon nanotubes by resonance Raman spectroscopy. Appl. Phys. Lett. 85, 1006-1008 (2004).
41. Kim, S. N., Luo, Z. T. & Papadimitrakopoulos, F. Diameter and metallicity dependent redox influences on the separation of single-wall carbon nanotubes. Nano Lett. 5, 2500-2504 (2005).
42. Chen, Z. H. et al. Bulk separative enrichment in metallic or semiconducting single-walled carbon nanotubes. Nano Lett. 3, 1245-1249 (2003).
43. Park, N. et al. Band gap sensitivity of bromine adsorption at carbon nanotubes. Chem. Phys. Lett. 403, 135-139 (2005).
44. Lu, J. et al. Selective interaction of large or charge-transfer aromatic molecules with metallic single-wall carbon nanotubes: Critical role of the molecular size and orientation. J. Am. Chem. Soc. 128, 5114-5118 (2006).
45. McDonald, T. J., Engtrakul, C., Jones, M., Rumbles, G. & Heben, M. J. Kinetics of PL quenching during single-walled carbon nanotube rebundling and diameter-dependent surfactant interactions. J. Phys. Chem. B 110, 25339-25346 (2006).
46. McDonald, T. J., Blackburn, J. L., Metzger, W. K., Rumbles, G. & Heben, M. J. Chiral-selective protection of single-walled carbon nanotube photoluminescence by surfactant selection. J. Phys. Chem. C 111, 17894-17900 (2007).
47. Li, H. P. et al. Selective interactions of porphyrins with semiconducting single-walled carbon nanotubes. J. Am. Chem. Soc. 126, 1014-1015 (2004).
48. Peng, X. et al. Optically active single-walled carbon nanotubes. Nature Nanotech. 2, 361-365 (2007).
49. Peng, X., Komatsu, N., Kimura, T. & Osuka, A. Improved optical enrichment of SWNTs through extraction with chiral nanotweezers of 2,6-pyridylene-bridged diporphyrins. J. Am. Chem. Soc. 129, 15947-15953 (2007).
50. Chen, F. M., Wang, B., Chen, Y. & Li, L. J. Toward the extraction of single species of single-walled carbon nanotubes using fluorene-based polymers. Nano Lett. 7, 3013-3017 (2007).
51. Nish, A., Hwang, J. Y., Doig, J. & Nicholas, R. J. Highly selective dispersion of single walled carbon nanotubes using aromatic polymers. Nature Nanotech. 2, 640-646 (2007).
52. Hwang, J. Y. et al. Polymer structure and solvent effects on the selective dispersion of single-walled carbon nanotubes. J. Am. Chem. Soc. 130, 3543-3553 (2008).
53. Fantini, C., Jorio, A., Santos, A. P., Peressinotto, V. S. T. & Pimenta, M. A. Characterization of DNA-wrapped carbon nanotubes by resonance Raman and optical absorption spectroscopies. Chem. Phys. Lett. 439, 138-142 (2007).
54. Shin, H.-J. et al. Tailoring electronic structures of carbon nanotubes by solvent with electrondonating and -withdrawing groups. J. Am. Chem. Soc. 130, 2062-2066 (2008).
55. Tromp, R. M., Afzali, A., Freitag, M., Mitzi, D. B. & Chen, Z. Novel strategy for diameter-selective separation and functionalization of single-wall carbon nanotubes. Nano Lett. 8, 469-472 (2008).
56. Nagasawa, S., Yudasaka, M., Hirahara, K., Ichihashi, T. & Iijima, S. Effect of oxidation on single-wall carbon nanotubes. Chem. Phys. Lett. 328, 374-380 (2000).
57. Miyata, Y. et al. Chirality-dependent combustion of single-walled carbon nanotubes. J. Phys. Chem. C 111, 9671-9677 (2007).
58. Yang, C. M. et al. Preferential etching of metallic single-walled carbon nanotubes with small diameter by fluorine gas. Phys. Rev. B 73, 075419 (2006).
59. Zhang, G. Y. et al. Selective etching of metallic carbon nanotubes by gas-phase reaction. Science 314, 974-977 (2006).
60. Collins, P. C., Arnold, M. S. & Avouris, P. Engineering carbon nanotubes and nanotube circuits using electrical breakdown. Science 292, 706-709 (2001).
61. Collins, P. G., Hersam, M., Arnold, M., Martel, R. & Avouris, P. Current saturation and electrical breakdown in multiwalled carbon nanotubes. Phys. Rev. Lett. 86, 3128-3131 (2001).
62. Huang, H. J., Maruyama, R., Noda, K., Kajiura, H. & Kadono, K. Preferential destruction of metallic single-walled carbon nanotubes by laser irradiation. J. Phys. Chem. B 110, 7316-7320 (2006).
63. Zhang, Y., Zhang, Y., Xian, X., Zhang, J. & Liu, Z. Sorting out semiconducting single-walled carbon nanotube arrays by preferential destruction of metallic tubes using xenon-lamp irradiation. J. Phys. Chem. C 112, 3849-3856 (2008).
64. Heller, D. A. et al. Concomitant length and diameter separation of single-walled carbon nanotubes. J. Am. Chem. Soc. 126, 14567-14573 (2004).
65. Vetcher, A. A. et al. Fractionation of SWNT/nucleic acid complexes by agarose gel electrophoresis. Nanotechnology 17, 4263-4269 (2006).
66. Doorn, S. K. et al. High resolution capillary electrophoresis of carbon nanotubes. J. Am. Chem. Soc. 124, 3169-3174 (2002).
67. Doorn, S. K. et al. Capillary electrophoresis separations of bundled and individual carbon nanotubes. J. Phys. Chem. B 107, 6063-6069 (2003).
68. Krupke, R., Hennrich, F., von Lohneysen, H. & Kappes, M. M. Separation of metallic from semiconducting single-walled carbon nanotubes. Science 301, 344-347 (2003).
69. Krupke, R., Hennrich, F., Kappes, M. M. & Lohneysen, H. V. Surface conductance induced dielectrophoresis of semiconducting single-walled carbon nanotubes. Nano Lett. 4, 1395-1399 (2004).
70. Krupke, R., Linden, S., Rapp, M. & Hennrich, F. Thin films of metallic carbon nanotubes prepared by dielectrophoresis. Adv. Mater. 18, 1468-1470 (2006).
71. Hong, S., Jung, S., Choi, J., Kim, Y. & Baik, S. Electrical transport characteristics of surface-conductance-controlled, dielectrophoretically separated single-walled carbon nanotubes. Langmuir 23, 4749-4752 (2007).
72. Lutz, T. & Donovan, K. J. Macroscopic scale separation of metallic and semiconducting nanotubes by dielectrophoresis. Carbon 43, 2508-2513 (2005).
73. Peng, H. Q., Alvarez, N. T., Kittrell, C., Hauge, R. H. & Schmidt, H. K. Dielectrophoresis field flow fractionation of single-walled carbon nanotubes. J. Am. Chem. Soc. 128, 8396-8397 (2006).
74. Liu, J. et al. Fullerene pipes. Science 280, 1253-1256 (1998).
75. Chen, B. L. & Selegue, J. P. Separation and characterization of single-walled and multiwalled carbon nanotubes by using flow field-flow fractionation. Anal. Chem. 74, 4774-4780 (2002).
76. Zheng, M. et al. DNA-assisted dispersion and separation of carbon nanotubes. Nature Mater. 2, 338-342 (2003).
77. Strano, M. S. et al. Understanding the nature of the DNA-assisted separation of single-walled carbon nanotubes using fluorescence and Raman spectroscopy. Nano Lett. 4, 543-550 (2004).
78. Zheng, M. et al. Structure-based carbon nanotube sorting by sequence-dependent DNA assembly. Science 302, 1545-1548 (2003).
79. Lustig, S. R., Jagota, A., Khripin, C. & Zheng, M. Theory of structure-based carbon nanotube separations by ion-exchange chromatography of DNA/CNT hybrids. J. Phys. Chem. B 109, 2559-2566 (2005).
80. Duesberg, G. S., Muster, J., Krstic, V., Burghard, M. & Roth, S. Chromatographic size separation of single-wall carbon nanotubes. Appl. Phys. A 67, 117-119 (1998).
81. Farkas, E., Anderson, M. E., Chen, Z. H. & Rinzler, A. G. Length sorting cut single wall carbon nanotubes by high performance liquid chromatography. Chem. Phys. Lett. 363, 111-116 (2002).
82. Huang, X. Y., McLean, R. S. & Zheng, M. High-resolution length sorting and purification of DNAwrapped carbon nanotubes by size-exclusion chromatography. Anal. Chem. 77, 6225-6228 (2005).
83. Arnold, K., Hennrich, F., Krupke, R., Lebedkin, S. & Kappes, M. M. Length separation studies of single walled carbon nanotube dispersions. Phys. Status Solidi B 243, 3073-3076 (2006).
84. Bauer, B. J., Fagan, J. A., Hobbie, E. K., Chun, J. & Bajpai, V. Chromatographic fractionation of SWNT/DNA dispersions with on-line multi-angle light scattering. J. Phys. Chem. C 112, 1842-1850 (2008).
85. Chattopadhyay, D., Lastella, S., Kim, S. & Papadimitrakopoulos, F. Length separation of Zwitterion-functionalized single wall carbon nanotubes by GPC. J. Am. Chem. Soc. 124, 728-729 (2002).
86. Zheng, M. & Semke, E. D. Enrichment of single chirality carbon nanotubes. J. Am. Chem. Soc. 129, 6084-6085 (2007).
87. Zhang, L. et al. Assessment of chemically separated carbon nanotubes for nanoelectronics. J. Am. Chem. Soc. 130, 2686-2691 (2008).
88. O'Connell, M. J. et al. Band gap fluorescence from individual single-walled carbon nanotubes. Science 297, 593-596 (2002).
89. Wei, L. et al. Selective enrichment of (6,5) and (8,3) single-walled carbon nanotubes via cosurfactant extraction from narrow (n,m) distribution samples. J. Phys. Chem. B 112, 2771-2774 (2008).
90. Green, A. A. & Hersam, M. C. Ultracentrifugation of single-walled nanotubes. Mater. Today 10, 59-60 (December 2007).
91. Nair, N., Kim, W.-J., Braatz, R. D. & Strano, M. S. Dynamics of surfactant-suspended single-walled carbon nanotubes in a centrifugal field. Langmuir 24, 1790-1795 (2008).
92. Arnold, M. S., Stupp, S. I. & Hersam, M. C. Enrichment of single-walled carbon nanotubes by diameter in density gradients. Nano Lett. 5, 713-718 (2005).
93. Arnold, M. S., Green, A. A., Hulvat, J. F., Stupp, S. I. & Hersam, M. C. Sorting carbon nanotubes by electronic structure using density differentiation. Nature Nanotech. 1, 60-65 (2006).
94. Zhu, Z. P. et al. Pump-probe spectroscopy of exciton dynamics in (6,5) carbon nanotubes. J. Phys. Chem. C 111, 3831-3835 (2007).
95. Qian, H. et al. Exciton energy transfer in pairs of single-walled carbon nanotubes. Nano Lett. 8, 1363-1367 (2008).
96. Crochet, J., Clemens, M. & Hertel, T. Quantum yield heterogeneities of aqueous single-wall carbon nanotube suspensions. J. Am. Chem. Soc. 129, 8058-8059 (2007).
97. Hennrich, F. et al. Diameter sorting of carbon nanotubes by gradient centrifugation: Role of endohedral water. Phys. Status Solidi B 244, 3896-3900 (2007).
98. Green, A. A. & Hersam, M. C. Colored semitransparent conductive coatings consisting of monodisperse metallic single-walled carbon nanotubes. Nano Lett. 8, 1417-1422 (2008).
99. Yanagi, K., Miyata, Y. & Kataura, H. Optical and conductive characteristics of metallic single-wall carbon nanotubes with three basic colors: Cyan, magenta, and yellow. Appl. Phys. Express 1, 034003 (2008).
100. Miyata, Y., Yanagi, K., Maniwa, Y. & Kataura, H. Highly stabilized conductivity of metallic single wall carbon nanotube thin films. J. Phys. Chem. C 112, 3591-3596 (2008).
101. Kong, J., Soh, H. T., Cassell, A. M., Quate, C. F. & Dai, H. J. Synthesis of individual single-walled carbon nanotubes on patterned silicon wafers. Nature 395, 878-881 (1998).
102. Kang, S. J. et al. High-performance electronics using dense, perfectly aligned arrays of single-walled carbon nanotubes. Nature Nanotech. 2, 230-236 (2007).
103. Hata, K. et al. Water-assisted highly efficient synthesis of impurity-free single-walled carbon nanotubes. Science 306, 1362-1364 (2004).
104. Cassell, A. M., Raymakers, J. A., Kong, J. & Dai, H. J. Large scale CVD synthesis of single-walled carbon nanotubes. J. Phys. Chem. B 103, 6484-6492 (1999).
105. Huang, S. M., Cai, X. Y. & Liu, J. Growth of millimeter-long and horizontally aligned single-walled carbon nanotubes on flat substrates. J. Am. Chem. Soc. 125, 5636-5637 (2003).
106. Bandow, S. et al. Effect of the growth temperature on the diameter distribution and chirality of single-wall carbon nanotubes. Phys. Rev. Lett. 80, 3779-3782 (1998).
107. Nikolaev, P. et al. Gas-phase catalytic growth of single-walled carbon nanotubes from carbon monoxide. Chem. Phys. Lett. 313, 91-97 (1999).
108. Hiraoka, T., Bandow, S., Shinohara, H. & Iijima, S. Control on the diameter of single-walled carbon nanotubes by changing the pressure in floating catalyst CVD. Carbon 44, 1853-1859 (2006).
109. Wang, B. et al. Pressure-induced single-walled carbon nanotube (n,m) selectivity on Co-Mo catalysts. J. Phys. Chem. C 111, 14612-14616 (2007).
110. Maruyama, S., Kojima, R., Miyauchi, Y., Chiashi, S. & Kohno, M. Low-temperature synthesis of high-purity single-walled carbon nanotubes from alcohol. Chem. Phys. Lett. 360, 229-234 (2002).
111. Wang, B. et al. (n,m) selectivity of single-walled carbon nanotubes by different carbon precursors on Co-Mo catalysts. J. Am. Chem. Soc. 129, 9014-9019 (2007).
112. Sinnott, S. B. et al. Model of carbon nanotube growth through chemical vapor deposition. Chem. Phys. Lett. 315, 25-30 (1999).
113. Kitiyanan, B., Alvarez, W. E., Harwell, J. H. & Resasco, D. E. Controlled production of single-wall carbon nanotubes by catalytic decomposition of CO on bimetallic Co-Mo catalysts. Chem. Phys. Lett. 317, 497-503 (2000).
114. Bachilo, S. M. et al. Narrow (n,m)-distribution of single-walled carbon nanotubes grown using a solid supported catalyst. J. Am. Chem. Soc. 125, 11186-11187 (2003).
115. Li, X. L. et al. Selective synthesis combined with chemical separation of single-walled carbon nanotubes for chirality selection. J. Am. Chem. Soc. 129, 15770-15771 (2007).
116. Li, Y. M. et al. Preferential growth of semiconducting single-walled carbon nanotubes by a plasma enhanced CVD method. Nano Lett. 4, 317-321 (2004).
117. Wang, Y. et al. Direct enrichment of metallic single-waited carbon nanotubes induced by the different molecular composition of monohydroxy alcohol homologues. Small 3, 1486-1490 (2007).
118. Wang, Y. H. et al. Continued growth of single-walled carbon nanotubes. Nano Lett. 5, 997-1002 (2005).
119. Smalley, R. E. et al. Single wall carbon nanotube amplification: En route to a type-specific growth mechanism. J. Am. Chem. Soc. 128, 15824-15829 (2006).
120. Ogrin, D. et al. Amplification of single-walled carbon nanotubes from designed seeds: Separation of nucleation and growth. J. Phys. Chem. C 111, 17804-17806 (2007).
121. Iwasaki, T., Robertson, J. & Kawarada, H. Mechanism analysis of interrupted growth of single-walled carbon nanotube arrays. Nano Lett. 8, 886-890 (2008).
122. Yan, Y. H., Chan-Park, M. B. & Zhang, Q. Advances in carbon-nanotube assembly. Small 3, 24-42 (2007).