Multifunctionalized carbon nanotubes as advanced multimodal nanomaterials for biomedical applications

The increasing importance of nanotechnology in the field of biomedical applications has encouraged the development of new nanomaterials endowed with multiple functions. Novel nanoscale drug delivery systems with diagnostic, imaging and therapeutic properties hold many promises for the treatment of different types of diseases, including cancer, infection and neurodegenerative syndromes. Functionalized carbon nanotubes (CNTs) are one of the most recent type of nanomaterial developed in biomedicine as they can be designed and imparted with multimodal capabilities. Indeed, the possibility of inserting different functionalities on CNTs is opening the possibility to exploit them on new strategies that combine diagnosis with improved therapeutic efficacies. In this review, we describe the different approaches that have been recently developed to generate multifunctionalized CNTs for biomedical applications. In particular, covalent and noncovalent double and triple functionalization methods are discussed, putting in evidence their use in vitro and in vivo and highlighting the advantages and the drawbacks of these new systems. Preclinical studies have demonstrated that multifunctional CNTs are highly promising when combining diagnostic, imaging and therapeutic modalities.