Carbon nanotube-based vectors for delivering immunotherapeutics and drugs

Administration of drugs is very often limited by problems of insolubility, inefficient distribution, lack of selectivity and side-effects raising health concerns. Currently, most of these problems are the subject of very intense studies, aiming to improve efficiency, availability and toxicity profiles. In addition, cell membranes that act as barriers can pose a problem in drug delivery by selectively allowing only certain structures to pass based on hydrophilicity: hydrophobicity ratios. Among the currently available delivery systems, which include liposomes, emulsions, polymers and microparticles [1–3], carbon nanotubes (CNTs) have recently gained high popularity as potential drug carriers, therapeutic agents and for applications in diagnosis . CNTs possess a unique and fascinating one-dimensional nanostructure, which imparts intriguing properties to the nanomaterial, such as tremendous strength, high thermal conductivity and amazing electronic properties ranging from metallic to semiconducting. These all-carbon hollow graphitic tubes with high aspect and nanoscale diameter can be classified by their structure into two main types: single-walled CNTs (SWNTs), which consist of a single layer of graphene sheet seamlessly rolled into a cylindrical tube, and multiwalled CNTs  (MWNTs), which comprise multiple layers of concentric cylinders with a space of about 0.34 nm between the adjacent layers (Fig. 3.1).