On the other hand, CNTs can persist in the body for weeks, months, or even years, thus limiting their use for repeated treatments [15, 21]. If we talk about dendrimers, they are synthetic, branched macromolecules that form a treelike structure whose synthesis represents a relatively new field in polymer chemistry. Though promising, dendrimers are more expensive than other nanocarriers like CNTs and require many repetitive Inhibitors,research,lifescience,medical steps for synthesis, posing a challenge for large-scale
production . In the recent years of research, reported data clearly reveals that CNTs have an enormous potential and possess high entrapment efficiency to carry the therapeutic molecule as earliest to the site of cancer cell without activating the immune system and damage to other viable cells although Inhibitors,research,lifescience,medical toxicity issues related to CNTs are under research. This review highlights the insights of the CNTs and their potency in delivering the anticancer drugs to combat various metastatic cancer cells specifically. 2. Production of CNTs The production of CNTs see more complies with the transformation of a carbon source
Inhibitors,research,lifescience,medical into nanotubes, usually at high temperature and low pressure, wherein the synthesis conditions influence the characteristics of the final product. Since prepared CNTs are usually associated with carbonaceous or metallic impurities, therefore, purification is an essential step to be considered . Methods of CNTs purification include chemical methods, particularly oxidation (gas phase , liquid phase ), physical methods (filtration , centrifugation , and high temperature annealing Inhibitors,research,lifescience,medical , etc.), and multistep purification Inhibitors,research,lifescience,medical . Presently, there are three main approaches
for the synthesis of CNTs (Figures (Figures22 and and3)3) including electric arc discharge, the laser ablation and the chemical vapor deposition (CVD). Figure 2 Schematic representation of methods used for carbon Thalidomide nanotube synthesis: (a) Arc discharge method, (b) chemical vapour deposition method, (c) laser ablation method. Figure 3 Mechanism of carbon nanotube synthesis: (a) Arc discharge method, (b) chemical vapor deposition method, and (c) laser ablation method. 2.1. Arc Discharge Method This method is the oldest method used by Iijima in 1991 when CNTs were first identified . Figures 2(a) and 3(a) showed the synthesis of CNTs by arc discharge method. In this method, an arc is generated, when a DC current of 200A to 20V is applied across two carbon electrodes which are placed in a vacuum chamber that is typically filled with inert gas (Helium, argon) at low pressure (~50~700mbar). The positive electrode is gradually brought closer to the negative one to strike the electric arc.