Production, Purification and Functionalization of Carbon Nanotubes for Medical Applications

Carbon nanotubes (CNTs) are needle-like potential carriers of bioactive including drug, genes and proteins.This review considers several techniques that have been developed for fabricating, purifying and functionalizing CNT structures.Commonly, three techniques are being used for producing CNTs: the carbon arc-discharge technique; the laser-ablation and chemical vapor deposition (CVD) technique.Carbon nanotube usually contains a large amount of impurities such as metal particles, amorphous carbon, and multishells.So purification is needed before attachment of drugs onto CNTs.Depending on technique of their synthesis and types of nano tubes, there are many different methods and procedure for purification.Almost all purification procedures have the following main steps: deletion of large graphite particles and aggregations with filtration, dissolution in appropriate solvents to eliminate catalyst particles (concentrated acids as solvent) and fullerenes (use of organic solvents), and microfiltration and chromatography to size separation and remove the amorphous carbon clusters.Generally there are two methods of carbon nanotube purifications these are chemical method and physical methods.Raw carbon nanotubes have highly hydrophobic surfaces, and are not soluble in aqueous solutions.For medical applications, surface chemistry modifications or functionalization is required to solubilize CNTs in aqueous solvent, improve biocompatibility and to decrease the toxicity of CNTs to the normal cells.