Stimuli‑Responsive Carbon Nanotubes for On‑Demand Cancer Therapy: A Review

Stimuli-responsive carbon nanotubes (CNTs) have emerged as transformative nanocarriers in precision oncology due to their
unique physicochemical, optical, and mechanical properties, enabling controlled, targeted drug delivery. This review presents
a comprehensive analysis of CNT-based systems engineered to respond to specific internal (pH, redox, and enzymatic) and
external (light, temperature, magnetic, and ultrasound) stimuli for on-demand cancer therapy. The discussion covers synthesis
methods, structural differences between single- and multi-walled CNTs, and diverse functionalization strategies that enhance
solubility, biocompatibility, and stimuli responsiveness. The crucial advances in CNT-based delivery systems demonstrate
their ability to achieve spatiotemporal control over drug release, improve tumour penetration, and minimize systemic toxicity
through mechanisms such as pH-triggered drug detachment, GSH-mediated redox cleavage, and NIR-induced photothermal
ablation. Integrating CNTs with polymers, peptides, and metal nanoparticles further enables multimodal applications,
including chemo-photothermal, chemo-immuno, and gene therapies. Despite remarkable progress, challenges remain in
understanding long-term pharmacokinetics, immunogenicity, and biodistribution, as well as in establishing standardized
synthesis and regulatory frameworks. The review highlights emerging trends such as AI-driven CNT design, predictive
pharmacokinetic modelling, and personalized nanomedicine, emphasizing their potential to revolutionize cancer treatment
by achieving precise, adaptive, and patient-specific therapy.
Keywords Stimuli-responsive nanocarriers · Carbon nanotubes (CNTs) · Targeted drug delivery · Photothermal therapy
(PTT) · Cancer nanomedicine