Application of metal-based nanoparticles in targeted drug delivery to breast cancer stem cells

Breast cancer stem cells (BCSCs) are a minor population within breast cancer tissue, causing cancer development and cancer recurrence due to stem-like and malignant properties, including self-renewal, proliferation, differentiation, migration, invasion, metastasis, and resistance to chemo/radio therapy. Treatment of these types of cancer cells requires targeted approaches to address the unique properties of BCSCs. Metal nanoparticles (MNPs) can be applied as drug delivery nanosystems in the treatment of BCSCs. Breast cancer treatments by MNP-based targeted drug delivery are essential because they reduce patient discomfort and recovery time, while enabling more precise and targeted therapy, potentially reducing off-target effects when appropriately designed and dosed. The size, shape, surface characteristics, and unique properties of MNPs, including their optical and physicochemical characteristics, safety profiles that are highly dependent on particle design and administration parameters, stability, circulation half-life, biodistribution, and high drug release efficiency, make them highly reactive and versatile for a variety of biomedical applications. However, their safety profiles are strongly influenced by particle design, dosage, and administration parameters, as high concentrations may induce dose-dependent toxicity, including ROS-mediated cellular damage. This review focuses on applications of various MNPs, including gold, copper, iron oxide, and silver, their surface modifications, and combination with photothermal therapy and several therapeutic agents in the drug delivery of BCSCs. This review also highlights the advantages, current challenges, and prospects of MNPs in drug delivery systems. These promising approaches have significant potential for developing new strategies for invasive treatment of breast cancer.