Carbon Nanomaterials for Drug Delivery

Carbon nanomaterials with unique nanostructure (CMNS) are the most studied materials in nanotechnology, despite some conflicting results about their safety profiles [1, 2]. Although their structures are simple, carbon nanomaterials provide exceptional physical and chemical properties including high electrical and thermal conductivities, unique optical properties, and extreme chemical stability. The field concerning nanostructured carbon materials is the most rapidly developing research field in the past decades due to their potential applications in all fields that might affect our lives [3]. One of the greatest values of carbon nanomaterials will be in the development of new and effective medical treatments, particularly for the therapy of various diseases [4]. The predominately nanostructured carbon materials are graphene (GN, 2-D, sp2 carbon), carbon nanotubes (CNTs, 1-D, sp2 carbon), and carbon nanohorns (CNHs, 1-D, sp2 carbon) and nanodiamonds (NDs, 0-D, sp3 carbon). GN is a two-dimensional structure, while the CNT is regarded as the GN rolling up into the seamless tubular hollow cylinder in nanoneedle shape. In the case of CNHs, the single GN sheet rolled into a cone. The structures of different materials are shown in Fig. 2.1. Despite the four types of carbon materials are different in shapes, they are all nanostructured materials with many intriguing features that make them attractive drug delivery carriers [5]. Firstly, the nanostructured carbon materials can disperse in aqueous solutions. Besides from direct translocation through cellular membranes, the CMNS also present the ability to enter cells via energy-dependent endocytic pathways [6]. Secondly, they can enter and accumulate in tumor tissues via the