Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5412_Библиотеки_им_академика_М_И_Перельмана

The last 20years have seen a boom in the biomedical and nanomedicine sectors due to advances in nanoscience technology. There has been substantial growth in the signicance of nanotechnology for biomedicines, drug and gene delivery, biosen­sors, and tissue engineering-related applications. Various nanomaterials, including carbon-based nanomaterials (CBNs) with their distinct physicochemical characteris­tics, morphological advancements, and functionalization ability, have unlocked novel avenues in the biomedical eld [1]. In addition, applications of CBNs in the realms of energy, the environment, electronics, optics, and health care all show consider­able potential. Carbon could bond in various ways to form structures with utterly unique characteristics. The chemical element carboncontains six electrons that are located in the 1s2, 2s2, and 2p2 atomic orbitals andare capable of forming sp, sp2, or sp3 hybrids. The biomedical sector has been stimulated by the discovery of sp2 carbon-bonded materials with relatively constant nanoscale sizes, such as graphene, graphene oxide (GO), graphene quantum dots (GQDs) fullerenes, and carbon nano­tubes (CNTs). Graphene is the source of most of the physical characteristics of CBNs. The consistent atomic-scale hexagonal honeycomb (sp2-bonded) arrangement of the carbon atoms in graphene serves as the fundamental framework for itssp2 carbon-bonded allotropes, including fullerenes and carbon nanotubes. Theoretically, a carbon nanotube is unique since it is made of a rolled-up graphene sheet, which can be of single or multiple wells [2]. Nanotubes having a single well are known as single-wall carbon nanotubes (SWCNTs) and were originally documented in 1993 [3], whereas those with multiple wells are recognized as multiwall carbon nanotubes (MWCNTs) and were discovered in 1991 by Iijima [4].

CNTs are one-dimensional graphitic morphologies formed by rolling graphite/ graphene sheets, which may form diverse carbon allotropes along with graphite and fullerenes. Nanotubes resemble buckytubes with a cylindrical shape and feature unique properties that make CNTs valuable for numerous real-world applications. CNTs exhibit superior mechanical, electrical, thermal, and optical properties. Nano­tubes are integrated withextraordinary stiffness andresilience, as well as reversible folding and collapsing. CNTs are one of the most rigid substances known and yet have the potential of elastic deformation after exerting compressive stresses. This is due to the strong C-C bond stiffness of the hexagonal network, which results in an axial Young’s modulus (E) of ~1 TPa with tensile strength (σ) of150 GPa[5]. In addition to simple elements, these carbon assemblages may generate a variety of congurations and forms [3–7]. Beneath high pressure, nanotubes can merge, exchanging numerous

Since the dawn of the 21st century, CNTs have been extensively utilized in phar­maceutical and biomedical applications as drug delivery. They stand out beyond bulk counterparts with the similar constitution (in microscale) due to their ultra-small size, high reactivity, needle-like morphology, signicant strength, adaptable inter­action with cargo, higher drug loading efciency, exceptional electrical and opti­cal properties, good stability, biocompatibility, and potential to deliver therapeutic molecules at specic or targetedsites and enormous surface area to mass ratio [6,7]. Furthermore, CNTs have been discovered to be an effective drug delivery vehicle since they directly enter cells and maintain the drug moleculesintact without metab­olizing them during delivery. CNTs, including SWCNTs and MWCNTs, can conju­gate or absorb numeroustherapeutic molecules, including drugs,antibodies, nucleic acids,proteins, and enzymes. Although these characteristics are linked to highly desirable attributes,CNTs exhibit toxicity and biodegradability-related issues, which further limit their adaptability for biomedical applications. Nevertheless, despite cer­tain drawbacks, CNTs remain to perform admirably in the eld of medicine, par­ticularly in the areas of drug delivery systems (DDSs), gene therapy, bioimaging, andbiosensors [5,7].

The major challenges related to the application of CNTs in biomedical elds include lack of solubility, dispersibility, biodistribution, bioactivity, biodegradability, and toxicity. These inadequacies are mainly attributed to the hydrophobic structure, van der Waals interactions, and the length of the CNTs, along with the nonuniformity in their surface characteristics. However, the functionalization of CNTs with hydro­philic and more biocompatible functional elements such as biopolymers and target­ing ligands can overcome these challenges. Also, it is much obligatory to tune the dimensions of the CNTs utilizing suitable synthesis approaches and process param­eters to counter their agglomeration tendency while improving the aqueous stability.

The CNTs, including SWCNTs and MWCNTs, can be synthesized using chemical vapor deposition, laser ablation, arc discharge, and ame-assisted synthesis methods. As stated before, in contrast to MWCNTs, the SWCNTs required certain metallic catalysts as a substrate for their synthesis. Certainly, each of the methods mentioned earlier demands specied precursors and process conditions. In line with this, the details related to the fabrication methods of CNTs are described as follows.