![]() Electric arc 4 and chemical vapor deposition (CVD) 5 are the main techniques for their production. The outer diameter of MWCNTs ranges from 2 to 100nm, while the inner diameter is in the range of 1-3nm, and their length is 1 to several μm. MWCNTs consist of several coaxial cylinders, each made of a single graphene sheet surrounding a hollow core. 3 SWCNTs are produced by the electric arc, laser ablation, chemical vapor deposition (CVD) and gas-phase catalytic processes (HiPco or High-Pressure Co-Conversion). ![]() SWCNTs are made up of single graphene layer wrapped into a hexagonal close-packed cylindrical structure whose diameter varies from 0.4-3.0nm and length ranges from 20-1000nm and are held together by van - der Waal forces, which makes them easily twistable and more pliable. 2 Depending on the number of sheets rolled into concentric cylinders, there are two broad categories of CNTs, namely, single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). 1 CNTs are graphene sheets rolled into a seamless cylinder that can be open ended or capped, having a high aspect ratio with diameters as small as 1nm and a length of several micrometers. Keywords: carbon nanotubes, SWCNTs, MWCNTs, functionalization, CNTs applications AbbreviationsĪfter the discovery of third allotropic form of carbon - fullerene in 1991, Sumio Iijima 1 identified a new structural form of this allotrope, the cylindrical fullerene and named them as carbon nanotubes (CNTs). The emission ranges of 800–2000 nm cover the biological tissue transparency window, which is therefore suitable for the imaging of biological systems through the luminescence created by semi–conducting SWCNTs. The semi–conducting SWCNTs exhibits photoluminescence in the near–infrared (NIR) region. CNT–based contrast agent may enhance molecular imaging by improving detection sensitivity and selectivity. CNTs can also be modified with positively charged bio–molecules such as ammonium group and cationic amino acid lysine, which lead to easy complex formation with genes of interest. Owing to their high carrying capacity, biocompatibility, and specificity to cells, various cancer as well diseased cells have been explored with CNTs for evaluation of pharmacokinetic parameters, cell viability, cytotoxicty, and drug delivery in cells. To be integrated into the biological systems, CNTs can be chemically modified or functionalised with therapeutically active molecules by forming stable covalent bonds or supra–molecular assemblies based on non–covalent interactions. ![]() ![]() CNTs can be considered as the nano–pharmaceuticals of choice depending on their vast application in drug delivery, drug targeting and in various other fields such as diagnostic, tissue regeneration. Methods such as: Electrical arc discharge, Laser ablation and Chemical vapor deposition are used to synthesize CNTs. Carbon nanotubes (CNTs) are third allotropic form of carbon–fullerenes which consist of graphite sheet rolled up into a cylindrical tube to form either single–wall (SWCNTs) or multi–wall (MWCNTs). ![]()
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