Green Synthesis, Spectroscopic Characterization and Biomedical Applications of Carbon Nanotubes

Carbon nanotubes are nano-sized cylindrical chicken wire-like structures made of carbon atoms. Carbon nanotubes have applications in electronics, energy storage, electromagnetic devices, environmental remediation and medicine as well. The biomedical applications of carbon nanotubes can be owed to features like low toxicity, non-immunogenicity, high in vivo stability and rapid cell entry. Carbon nanotubes have a great prospect in the treatment of diseases through diagnostic as well as therapeutic approaches. These nanostructures are interesting carriers for delivery and translocation of therapeutic molecules e.g. proteins, peptides, nucleic acids, drugs, etc. to various organs like the brain, lungs, liver, and pancreas. Commonly used methods to synthesize carbon nanotubes are arc discharge, chemical vapor deposition, pyrolysis, laser ablation etc. These methods have many disadvantages such as operation at high temperature, use of chemical catalysts, prolonged synthesis time and inclusion of toxic metallic particles in the final product requiring additional purification processes. In order to avoid these setbacks, various green chemistry-based synthetic methods have been devised, e.g., those involving interfacial polymerization, supercritical carbon dioxide drying, plant extract assisted synthesis, water- assisted synthesis, etc. This review will provide a thorough outlook of the eco-friendly synthesis of carbon nanotubes reported in the literature and their biomedical applications. Besides, the most commonly used spectroscopic techniques used for the characterization of carbon nanotubes are also discussed.