Stimuli-Responsive and Receptor-Targeted Carbon Nanotubes for Multimodal Cancer Therapy and Diagnosis

Carbon nanotubes (CNTs) are nanoscale tubular structures with significant potential as multifunctional delivery systems in the field of biomedicine, especially regarding cancer diagnosis and treatment. Due to their remarkable physicochemical properties, such as exceptional mechanical strength, high aspect ratio, excellent electrical and thermal conductivity, and lightweight nature, they are considered ideal candidates for incorporation into biomedical applications. The chemically adaptable surfaces of CNTs allow for functionalization with a variety of guest molecules, including drugs, imaging agents, and siRNA, thereby improving their biocompatibility and therapeutic effectiveness. To achieve targeted tumor delivery and retention, CNTs can be further modified with peptides, organic ligands, carbohydrates, or polymers, each tailored to designated biomedical functions. Stimuli-responsive CNT systems, classified as either endogenous or exogenous, have shown significant promise in enhancing therapeutic precision. This review examines the structural characteristics of CNTs and their applications as nanocarriers for targeted anticancer drug delivery. It highlights recent advancements in the development of receptor-targeted and stimuli-responsive CNT-based systems for improved cancer diagnostics and treatments. Additionally, it evaluates a range of CNT-enabled treatment modalities, including chemotherapy, photothermal and photodynamic therapy, radiotherapy, and biosensing, while critically assessing their related cytotoxic effects.