Carbon nanotubes can be described as a special kind of carbon containing cylindrical nanostructure-, which are chemically synthesized by an arc discharge or chemical vapor deposition of graphite . The shape of this carbon nano tubes are like rolling sheets of carbon containing the hollow tubes. The sizes of these nanotubes are tiny small generally ranges from, 0.3 to 3 nm in diameter of single-walled carbon nanotubes (SWCNTs) . This carbon nano tube can also be designed with with an addition of functional groups, targeting molecules, and polymers,to use it for biological applications and as consequence to enhance the solubility and biocompatibility . Ruggiero et al. described the biodistribution and glomerular filtration in the kidney of SWCNT with fluorescence label. This system was investigated to the near infrared (NIR) fluorescence imaging . For the improvementt of solubility of the carbon nanotubes, Liu et al. invented new water soluble carbon nanotubes functionalized with PEG . Carbon nanotubes are hexagonal networks of carbon atoms, 1 nm in diameter and 1-100 nm in length, as a layer of graphite rolled up into a cylinder. There are two types of nanotubes: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs), which differ in the arrangement of their graphene cylinders (Fig.2). (a) (b)
Fig.2: Structure of Carbon nanotubes (7)
Carbon nanotubes are small macromolecules that are unique for their size, shape, and have remarkable physical properties. Nanotubes posses some extra distinct advantages over other conventional drug delivery and diagnostic systems due to very interesting physicochemical properties such as ordered structure with high aspect ratio, ultra-light weight, high mechanical strength, high electrical conductivity, high thermal conductivity, metallic or semi-metallic behavior and high surface area. SWCNTs have unique potential uses in novel cancer therapies, specially when the drug delivery efficiency and their capacity to get absorbed NIR radiation are considered . The availabity of the carboxylic acid groups are suitable for the inclusion of moeity such as antibodies, glycoproteins, lectins, and carbohydrates, ehich inturn allow the SWCNTs to be applied to specifically target cancer affected tissues. Although,a huge efforts have been attempted to carefully investigate the in vitro and in vivo toxicity of CNTs, researchers still fail to reach consensus on the toxicity of CNTs [9,10].
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