Diameter-Selective Solubilization of Single-Walled Carbon Nanotubes by Reversible Cyclic Peptides

Ortiz-Acevedo, Alfonso; Xie, Hui; Zorbas, Vasiliki; Sampson, William M.; Dalton, Alan B.; Baughman, Ray H.; Draper, Rockford K.; Musselman, Inga H.; Dieckmann, Gregg R.

doi:10.1021/ja050507f

Cited by 160 publications

(155 citation statements)

References 26 publications

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“…in 2002, 71 ultrasonic processing has been used to isolate SWNTs in an extensive library of dispersing agents including surfactants, 119,130 polymers, 120 single-stranded DNA, 19,132,133 peptides, 134 and cagelike molecules such as Sarkosyl. 135 Figure 3-1 contrasts the appearance of an aqueous suspension containing mostly bundles and an aqueous sample enriched in isolated SWNTs.…”

Section: Motivationmentioning

confidence: 99%

Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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Single-walled carbon nanotubes (SWNTs) are cylindrical graphitic molecules that have remained at the forefront of nanomaterials research since 1991, largely due to their exceptional and unusual mechanical, electrical, and optical properties. The motivation for understanding how nanotubes interact with light (i.e., SWNT photophysics) is both fundamental and applied. Individual nanotubes may someday be used as superior near-infrared fluorophores, biological tags and sensors, and components for ultrahigh-speed optical communications systems. Establishing an understanding of basic nanotube photophysics is intrinsically significant and should enable the rapid development of such innovations. Unlike conventional molecules, carbon nanotubes are synthesized as heterogeneous samples, composed of molecules with different diameters, chiralities, and lengths. Because a nanotube can be either metallic or semiconducting depending on its particular molecular structure, SWNT samples are also mixtures of conductors and semiconductors. Early progress in understanding the optical characteristics of SWNTs was limited because nanotubes aggregate when synthesized, causing a mixing of the energy states of different nanotube structures. Recently, significant improvements in sample preparation have made it possible to isolate individual nanotubes, enabling many advances in characterizing their optical properties. In this Account, single-molecule confocal microscopy and spectroscopy were implemented to study the fluorescence from individual nanotubes. Single-molecule measurements naturally circumvent the difficulties associated with SWNT sample inhomogeneities. Intrinsic SWNT photoluminescence has a simple narrow Lorentzian line shape and a polarization dependence, as expected for a one-dimensional system. Although the local environment heavily influences the optical transition wavelength and intensity, single nanotubes are exceptionally photostable. In fact, they have the unique characteristic that their single molecule fluorescence intensity remains constant over time; SWNTs do not “blink” or photobleach under ambient conditions. In addition, transient absorption spectroscopy was used to examine the relaxation dynamics of photoexcited nanotubes and to elucidate the nature of the SWNT excited state. For metallic SWNTs, very fast initial recovery times (300–500 fs) corresponded to excited-state relaxation. For semiconducting SWNTs, an additional slower decay component was observed (50–100 ps) that corresponded to electron–hole recombination. As the excitation intensity was increased, multiple electron–hole pairs were generated in the SWNT; however, these e−h pairs annihilated each other completely in under 3 ps. Studying the dynamics of this annihilation process revealed the lifetimes for one, two, and three e−h pairs, which further confirmed that the photoexcitation of SWNTs produces not free electrons but rather one-dimensional bound electron–hole pairs (i.e., excitons). In summary, nanotube photophysics is a rapidly developing area o...

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Section: Motivationmentioning

confidence: 99%

Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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“…For example, it has been shown that open single-walled carbon nanotubes can accommodate small proteins such as cytochrome c inside their internal cavities, leading to the stable immobilization of the proteins in bioactive conformations [114]. Ortiz-Acevedo et al used a novel class of cyclic peptides containing alternating L-and Damino acids (AAs), called reversible cyclic peptides (RCPs), for the diameter-selective solubilization of HiPco single-walled carbon nanotubes [115] . In L-/D-peptides, all side chains reside on one face of the backbone, encouraging a ringlike conformation with the side chains on the ring exterior.…”

Section: Cnts/protein Conjugatesmentioning

confidence: 99%

Dispersions Based on Carbon Nanotubes – Biomolecules Conjugates

Capek¹

2011

Carbon Nanotubes - Growth and Applications

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“…As a result, alternative approaches using the non-covalent adsorption of surfactants (O'Connell, Bachilo et al 2002), polymers (Dalton, Blau et al 2001) and biomolecules Numata, Asai et al 2005) to solubilize the SWCNTs have been proposed and tested. To that end, much research attention has been focused on the design and utilization of polypeptide/CNT complexes because of their functionality in biological systems (Dieckmann, Dalton et al 2003;Zorbas, Ortiz-Acevedo et al 2004;Ortiz-Acevedo, Xie et al 2005;Pender, Sowards et al 2005;Karajanagi, Yang et al 2006;Su, Leung et al 2006) recently. We investigated the binding nature of three peptides (inactive NB1 and active B1 and B3) to single-walled carbon nanotubes (SWCNTs) using a density functional tight-binding (DFTB) method with an empirical vdW force correction (Fan, Zeng et al 2009).…”

Section: Peptidesmentioning

confidence: 99%