Amphiphiles nanotubes

Like small amphiphile nanotubes [14], block copolymer nanotubes should have potential applications in controlled deUvery and release [97,98], in encapsulation [99], and in nanoelectronics [100] etc. Although there have been reports on laboratory use of block copolymer nanofibers as vehicles for drug delivery [101], as scaffolds for cell growth [88,102], as precursors for ceramic magnetic nanowires [103,104], and as precursors for carbon nanofibers [105,106[, practical applications of block copolymer nanotubes have not been reported. This is probably due to the difficulty in making such structures. Their preparation from the self-assembly of block copolymers and interests from industry will likely change the scenery of nanotube appUca-tions in the futme. 

Permanent and permanent sculpted nanostructures are stable architectures. They can therefore be further chemically processed to yield more complex structures. For example, we have covalently linked different stable block copolymer nanostructures to yield coupled nanostructures. The end coupling of a hydrophobic nanotube with a hydrophilic nanotube yielded an amphiphilic nanotube diblock structure (Yan et al., 2004). The attachment of hydrophobic block copolymer nanotubes by their ends to the surfaces of hydrophilic nanospheres bearing carboxyl groups yielded a supersurfactant (Liu et al., 2003). 

Based on the multiple anodization approach and hydrophobic monolayer treatment of a nanotube layer, amphiphilic nanotubes consisting of bilayer nanotube arrays - one acting as hydrophobic and other as hydrophilic - can also be obtained (Fig. 8a(iv)) such arrays were proposed as a principle for drug delivery systems. ... 

Fig. 15 T1O2 nanotubes in drug delivery system, (a) Magnetic nanoparticle filled nanotubes with attached drug (F) for magnetically guided site selective drug delivery. Release is triggered by photocatalytic chain scission upon UV irradiation. Inset an example where a blue fluorescent molecule is released from magnetically actuated nanotubes (reproduced with permission from Ref 276). (b) Amphiphilic nanotubes loaded with drugs or biomolecules which are released upon opening the hydrophobic cap with UV irradiation (reproduced with permission from Ref 202).

Yuwono VM, Hartgerink JD (2007) Peptide amphiphile nanofibers template and catalyze silica nanotube formation. Langmuir 23 5033-5038... 

The cardanyl glycolipids behave as amphiphilic compounds and are able to self-assemble in water to form twisted fibers, helical coils, and high axial ratio nanotubes... 

Carbon nanotubes have been also used as a macromolecular scaffold for Gdm complexes. An amphiphilic gadolinium(III) chelate bearing a C16 chain was adsorbed on multiwalled carbon nanotubes (264). The resulting suspensions were stable for several days. Longitudinal water proton relaxivities, r] showed a strong dependence on the GdL concentration, particularly at low field. The relaxivities decreased with increasing field as predicted by the SBM theory. Transverse water proton relaxation times, T2, were practically independent of both the frequency and the GdL concentration. An in vivo feasibility MRI study has been... 

Figure 11. The HRTEM micrograph of VO2 4.(C16H33NH2)0.34 nanotubes (a rolled up superlattice of V205 layers separated by amphiphilic moities with amine head group) (39). (a) Side-on view of three nanotubes with unclosed caps and (b) cross-section of the nanotubes left zero-loss (electron energy) image, right vanadium (electron energy loss) image. [Courtesy of F. Krumeich and R. Nesper, ETH.]...

Arnold MS, Guler MO, Hersam MC, Stupp SI (2005) Encapsulation of carbon nanotubes by selfassembling peptide amphiphiles. Langmuir 21 4705 1709. 

Dieckmann GR, Dalton AB, Johnson PA, Razal J, Chen J, Giordano GM, Munoz E, Musselman IH, Baughman RH, Draper RK (2003) Controlled assembly of carbon nanotubes by designed amphiphilic peptide helices. J. Am. Chem. Soc. 125 1770-1777. 

Sinani VA, Gheith MK, Yaroslavov AA, Rakhnyanskaya AA, Sun K, Mamedov AA, Wicksted JP, Kotov NA (2005) Aqueous dispersions of single-wall and multiwall carbon nanotubes with designed amphiphilic polycations. Journal ofthe American Chemical Society 127 3463-3472. 

One characteristic feature of surfactants is their amphiphilic nature. These molecules present two moieties the hydrophobic moiety (usually a hydrocarbon chain) interacts with the nanotube sidewalls, while the hydrophilic part, called polar head group, is generally charged or has zwitterionic character. It has the double function of helping solubility in aqueous solvents and of providing additional stabilization towards tubes aggregation by coulombic charge repulsion. 

Jiao, J., et al., Decorating multi-watted carbon nanotubes with Au nanoparticles by amphiphilic ionic liquid self-assembly. Colloids and Surfaces A Physicochemical and Engineering Aspects, 2012. 408 p. 1-7. 

Figure 14.16 (a) Structure of amphiphile 14.10 (b and c) SEM images of self-assembled nanotubes... 

Shimizu T Masuda M Minamikawa H, Supramolecular nanotube architectures based on amphiphilic molecules, Chem. Rev., 2005, 105, 1401-1443. 

Dieckmann et al. in 2003 described an amphiphilic a-helical peptide specifically designed to coat and solubilize CNTs and to control the assembly of the peptide-coated nanotubes into macromolecular structures through peptide-peptide interactions between adjacent peptide-wrapped nanotubes [227]. They claimed that the peptide folds into an amphiphilic a-helix in the presence of carbon nanotubes and disperses them in aqueous solution by noncovalent interactions with the nanotube surface. EM and polarized Raman studies revealed that the peptide-coated nanotubes assemble into fibers with the nanotubes aligned along the fiber axis. The size and morphology of the fibers could be controlled by manipulating the solution conditions that affect peptide-peptide interactions [227]. 

Fukushima and Aida et al. reported that an achiral amphiphilic hexa-pen-hexabenzocoronene (HBC) 3 self-assembles into a helical coil and further into nanotubes in THF containing water (20% v/v) (Fig. 2) [37]. TEM revealed... 

Copper has been immobilized on glycylglycine bolaamphiphile peptide nanotubes that display histidine residues, and paramagnetic gadolinium, a magnetic resonance image contrast agent, has been immobilized on nanofibers produced from peptide amphiphiles (see Gazit, 2007 and references therein). 

Fibrillar superstructures were also obtained when the amphiphilic diphenylglucol-uril X was used to complex magneson, Y, by clipping onto the dihydroxphenyl unit. The clip molecules X formed globular associates, which transformed to nanotubes upon complexation of Y [426,427] Scheme 7. 

T. Shimizu, M. Masuda, H. Minamikawa, Supramolecular Nanotube Architectures Based on Amphiphilic Molecules , Chem. Rev., 105, 1401 (2005)... 

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