Colloidal nanotubes

These problems have been improved in recent years by the microfabrication of sharp tips with radii less than 10 nm, the observation in an SEM or STEM of the exact radius before and after the experiment, the use of robust carbon-nanotube probes, and general improvements in control electronics. However, another method used initially was the attachment of a small colloid particle in place of the AFM tip. These particles were considered a reasonably good approximation to a single-asperity contact their radii were accurately known and remained the same for the duration of the experiment. Such probes have also been used to investigate colloids where surface roughness is an important aspect of the colloid interaction. 

Si H-Y, Sun Z-H, Zhang H-L (2008) Photoelectrochemical response from CdSe-sensitized anodic oxidation Ti02 nanotubes. Colloids Surf A 313-314 604-607... 

Xin and co-workers modified the alkaline EG synthesis method by heating the metal hydroxides or oxides colloidal particles in EG or EG/water mixture in the presence of carbon supports, for preparing various metal and alloy nanoclusters supported on carbon [20-24]. It was found that the ratio of water to EG in the reaction media was a key factor influencing the average size and size distribution of metal nanoparticles supported on the carbon supports. As shown in Table 2, in the preparation of multiwalled carbon nanotube-supported Pt catalysts... 

K. Kneipp, A. Jorio, H. Kneipp, S.D.M. Brown, K. Shafer, J. Motz, R. Saito, G. Dresselhaus, and M.S. Dresslhaus, Polarization effects in surface-enhanced resonant Raman scattering of single-wall carbon nanotubes on colloidal silver clusters. Phys. Rev. B 63, 081401.1-081401.4 (2001). 

Y.H. Wu and S.S. Hu, The fabrication of a colloidal gold-carbon nanotubes composite film on a gold electrode and its application for the determination of cytochrome c. Colloid Surface B 41, 299-304 (2005). 

The approaches used for preparation of inorganic nanomaterials can be divided into two broad categories solution-phase colloidal synthesis and gas-phase synthesis. Metal and semiconductor nanoparticles are usually synthesized via solution-phase colloidal techniques,4,913 whereas high-temperature gas-phase processes like chemical vapor deposition (CVD), pulsed laser deposition (PLD), and vapor transfer are widely used for synthesis of high-quality semiconductor nanowires and carbon nanotubes.6,7 Such division reflects only the current research bias, as promising routes to metallic nanoparticles are also available based on vapor condensation14 and colloidal syntheses of high-quality semiconductor nanowires.15... 

Valenti LE, Fiorito PA, Garcia CD, Giacomelli CE (2007) The adsorption-desorption process of bovine serum albumin on carbon nanotubes. J. Colloid Interface Sci. 307 349-356. 

Foster J, Singamaneni S, Kattumenu R, Bliznyuk V (2005). Dispersion and phase separation of carbon nanotubes in ultrathin polymer films. J. Colloid and Interface Science 287 167-172. 

Li H, Wang DQ, Liu BL, Gao LZ (2004) Synthesis of a novel gelatin-carbon nanotubes hybrid hydrogel. Colloids and Surfaces B-Biointerfaces 33 85-88. 

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. 

Chromatographic approaches have been also used to separate nanoparticles from samples coupled to different detectors, such as ICP-MS, MS, DLS. The best known technique for size separation is size exclusion chromatography (SEC). A size exclusion column is packed with porous beads, as the stationary phase, which retain particles, depending on their size and shape. This method has been applied to the size characterization of quantum dots, single-walled carbon nanotubes, and polystyrene nanoparticles [168, 169]. Another approach is hydro-dynamic chromatography (HDC), which separates particles based on their hydro-dynamic radius. HDC has been connected to the most common UV-Vis detector for the size characterization of nanoparticles, colloidal suspensions, and biomolecules [170-172]. 

Yang XH, Wu QS, Li L, Ding YP, Zhang GX (2005) Controlled synthesis of the semiconductor CdS quasi-nanospheres, nanoshuttles, nanowires and nanotubes by the reverse micelle systems with different surfactants. Colloids Surf A 264 172-178... 

The number of studies on the health effects of fullerenes and carbon nanotubes is rapidly increasing. However, the data on their toxicity are often mutually contradictory. For example, the researchers from universities of Rice and Georgia (USA) found that in aqueous fullerene solutions colloidal nano-C particles were formed, which even at low concentration (approximately 2 molecules of fullerene per 108 molecules of water) negatively influence the liver and skin cells [17-19]. The toxicity of this nano-C aqueous dispersion was comparable to that of dioxins. In another smdy, however, it was shown that fullerene had no adverse effects and, on the contrary, had anti-oxidant activity [20]. Solutions of prepared by a variety of methods up to 200 mg/mL were not cytotoxic to a number of cell types [21]. The contradiction between the data of different authors could be explained by different nano-C particles composition and dispersion used in research. 

Sensor fabrication occurs in two steps. The first step is the immobilization of GOx on the surface of the nanotube. This is accomplished by adding GOx to a solution of surfactant stabilized nanotubes and dialyzing away the surfactant. Dialysis is an ideal method for assembling enzymes on a nanotube surface, because the method allows retention of enzyme activity while simultaneously maintaining nanotube colloidal stability. The resulting GOx-S WNT solution exhibits a shift in the nanotube fluorescence indicative of the enzyme layer being less tightly packed around the nanotube than the surfactant layer. The second step is addition of ferricyanide to the GOx-SWNT solution. Adsorption of ferricyanide to the nanotube surface... 

Gold colloids were observed both on the sides and at the ends of the nanotubes, indicating sidewall and termini modification. To confirm further the derivatiza-tion of the SWNTs, a perfluorinated marker was introduced by transesterification to allow the nanotubes to be probed by 19F NMR spectroscopy and XPS [160],... 

Many materials exist that have dimensions in the range of 1 rnn to several micrometers. Recall that colloidal particles (e.g., latex particles from emulsion polymerization, colloidal silica or alumina, etc.) fall in the range from about 10 nm to 1000 nm (1 jxm). A few examples of nanoparticles that are designed with more specific structures or geometries include carbon nanotubes, metal clusters, nanoscale magnetic crystals, and semiconducting ... 

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