He later presented his observations in 1960 wherein he described these carbon nanowhiskers as scroll-like structures ( Bacon, 1960). Subsequently, Bacon in 1956, while investigating the properties of carbon fibers in parma, observed CNTs in his samples. Their discovery went unnoticed as the article was published in Russian with a low circulation. The existence of CNTs dates back to 1952, when these nanofilaments were observed by two Russian scientists, LV Radushkevich and VM Lukyanovich. This is primarily responsible for a high tensile strength of 150 Gpa which in turn leads to higher C–C bond stiffness of the network ( Awasthi et al., 2005).ġ5.2. Origin and Historical Perspective of CNT Individual CNTs differ from each other in the number of carbon atoms, such as C 20, C 30, C 36, C 70, and C 78, and each of these individual members is called “graphene.” These hollow cylindrical tubes are thus arranged in a specific pattern to form hexagonal structural units. They are regarded as a third allotropic form of carbon with a typical length-to-diameter ratio of up to 28,000,000:1. A high aspect ratio, high surface area, rich surface chemistry, neutral electrostatic potential, extremely high drug cargo ability, and excellent material properties, such as ultimate electrical and thermal conductivities and mechanical strength, make them an attractive tool for biomedical applications ( Lu et al., 2009). In addition, the chapter also endeavors to provide a thoughtful insight into the toxicity and regulatory concerns that need to be addressed before the CNTs can be launched in the market.Ĭarbon nanotubes (CNTs), a sub-family of fullerenes (or bucky balls), are unique sp 2 hybridized pseudo-one-dimensional carbon allotropes with a C–C distance of approximately 1.4 Å. This chapter provides an overview of various types of CNTs, methods utilized for their commercial production, and the functionalization approaches employed in drug-delivery applications. The CNTs, favoring encapsulation of drug molecules or by possible attachment of theranostic agents on the nanotube walls, have enabled their use in controlled drug delivery, and in targeting of drug molecules to specific sites such as the lymphatic system, brain, ocular system, and cancerous tissue. The CNTs can be single-walled, double-walled or multi-walled, depending upon the number of graphene layers from which a single nanotube is composed. These rolled-up seamless cylinders of graphene sheets possess nanosized hollow-tube-shaped structures. Carbon nanotubes (CNTs) have attracted much attention from researchers worldwide in recent years due to their high aspect ratio, high surface area, and excellent material properties, such as electrical and thermal conductivities and mechanical strength.
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