Far-reaching advances in the role of carbon nanotubes in cancer therapy

Abstract

Cancer includes a group of diseases involving unregulated cell growth with the potential to invade or expand to other parts of the body, resulting in an estimate of 9.6 million deaths worldwide in 2018. Manifold studies have been conducted to design more efficacious techniques for cancer therapy due to the inadequacy of conventional treatments including chemotherapy, surgery, and radiation therapy. With the advances in the biomedical applications of nanotechnology-based systems, nanomaterials have gained increasing attention as promising vehicles for targeted cancer therapy and optimizing treatment outcomes. Owing to their outstanding thermal, electrical, optical and chemical properties, carbon nanotubes (CNTs) have been profoundly studied to explore the various perspectives of their application in cancer treatment. The current study aims to review the role of CNTs whether as a carrier or mediator in cancer treatment for enhancing the efficacy as well as the specificity of therapy and reducing adverse side effects. This comprehensive review indicates that CNTs have the capability to be the next generation nanomaterials to actualize noninvasive targeted eradication of tumors. However, further studies are needed to evaluate the consequences of their biomedical application before the transition into clinical trials, since possible adverse effects of CNTs on biological systems have not been clearly understood.

Introduction

Cancer includes a group of diseases involving unregulated cell growth with the potential to invade or expand to other parts of the body resulting in an estimate of 9.6 million deaths worldwide in 2018 [1]. Although numerous studies have been conducted to design new strategies for efficient cancer therapy, adjustment of cancer-related morbidity and mortality to an optimal level has not been achieved. The intrinsic shortcomings of conventional cancer treatment options such as surgical intervention, chemotherapy, and radiation therapy cause to rise the emergence of nanotechnology-based systems as a promising strategy for optimizing cancer therapy success by benefiting from the advantages and particular properties of nanoparticles for drug delivery, diagnosis, and imaging [2,3]. The unique properties such as high drug loading capacity and target site accumulation of nanomaterials such as liposomes, nanofibers, protein-based nanostructures, and inorganic nanoparticles introduced them as suitable carriers for overcoming biological barriers and pharmacokinetic obstacles like inadequate access of drugs to pathological sites, drug resistance at the cellular level, drug resistance at tumor microenvironment level, inefficient eradication of cancer stem cells and lack of specificity, in comparison to use of pristine anticancer drugs and traditional drug delivery systems [4,5].

Inorganic nanoparticles such as metal oxides, gold, and carbon-based nanomaterials, have gained increasing attention during the last decade as potential carriers for diagnostics and therapeutics of various cancers [[6], [7], [8], [9], [10], [11], [12], [13]]. Among inorganic nanoparticles, carbon nanotubes (CNTs) have been developed due to their exclusive physicochemical properties and high capability of binding to several materials including anticancer drugs, proteins, genes, etc. [14]. Single- and multi-walled carbon nanotubes (SWCNTs & MWCNTs) are the two types of CNTs with a broad range of features and functions have been extensively studied to explore the various perspectives of their application in cancer treatment. CNTs can be classified as mediators and nano-carriers for targeted cancer therapy [14]. In spite of expansive studies since their discovery, CNTs and their potential novel applications remain a hot topic for researchers in different disciplines. The aim of this study was to review the performance of SWCNTs and MWCNTs in cancer therapy either as a mediator or carrier, analyze the structure and mechanism of CNTs-based complex and their impact on several cancer cell lines both in-vitro and in vivo situation.

To review the effect of CNTs on cancer therapy, 8 main keywords including “carbon nanotubes”, “single-walled carbon nanotube”, “multi-walled carbon nanotubes”, “cancer treatment/therapy”, “cancer cell line” and “In vivo effect of CNTs on cancers” have been searched to found the relevant articles for 30 days. Over 500 articles were retrieved which were published from inception to June 2020. The search was narrowed to cover only the therapeutic effects of CNTs on cancers and the rest articles were removed from the references.