Mechanistic and translational nanomaterial-based strategies for targeting cancer stem cell resistance

Therapeutic resistance remains a major barrier in cancer control and is increasingly recognized as a cancer stem cell (CSC)-driven process rather than a result of residual tumor survival. CSCs sustain tumor initiation, progression, and recurrence through coordinated intrinsic and extrinsic mechanisms, including enhanced drug efflux, cellular quiescence, hypoxia tolerance, efficient DNA damage repair, metabolic adaptation, and phenotypic plasticity. These features render CSCs largely refractory to conventional chemotherapy, radiotherapy, and many molecularly targeted therapies. Although extensive efforts have focused on inhibiting CSC-associated signaling pathways, such as Wnt/β-catenin, Notch, Hedgehog, and PI3K/AKT/mTOR, clinical translation has been limited by pathway redundancy, compensatory signaling, poor tumor penetration, and systemic toxicity. Nanomaterial-based therapeutic platforms represent a promising investigational strategy with potential to address these limitations enabling multi-level intervention against CSC survival architectures. Rationally engineered nanomaterials-including metallic, carbon-based, MXene, and polymeric nanocarriers-enable multi-functional targeting of cancer stem cell resistance by enhancing intracellular delivery, modulating hypoxic niches, and inducing catalytic or photothermal cytotoxicity. These platforms integrate controlled release, ligand-mediated targeting, and microenvironment responsiveness to overcome efflux, quiescence, and repair-mediated survival pathways in CSCs. Nanomaterials bypass ATP-binding cassette transporter-mediated drug efflux, induce cell-cycle-independent cytotoxicity, remodel hypoxic niches, overwhelm DNA repair capacity, and constrain phenotypic plasticity through coordinated pathway modulation. Photothermal and catalytic nanomaterials reduce or eliminate quiescent CSC populations. while ligand-functionalized nanocarriers targeting CSC markers such as CD44, CD133, and EpCAM enhance selective delivery and intracellular drug retention. This review integrates advances in CSC biology with emerging nanomaterial-based strategies and discusses translational challenges and future directions for achieving durable cancer control through CSC-targeted nanotherapy.