Baicalein-loaded rhamnolipid nanomicelles target mitochondrial dysfunction and activate the cGAS-STING pathway for triple-negative breast cancer therapy.

Triple-negative breast cancer (TNBC) remains an intractable malignancy due to the lack of specific therapeutic targets and high metastatic potential. Herein, we fabricated rhamnolipid (RL)-encapsulated baicalein (BAI) nanomicelles (RL/BAI) via a thin-film hydration method. Molecular dynamics (MD) simulations revealed that RL and BAI spontaneously assembled into stable nanomicelles (~100 nm) driven by van der Waals and hydrophobic interactions, achieving high encapsulation efficiency (~85 %) and excellent biocompatibility. In 4T1 cells, RL/BAI nanomicelles enhanced cellular uptake and achieved efficient mitochondrial colocalization, triggering mitochondrial membrane potential (MMP) collapse, excessive mitochondrial reactive oxygen species (mtROS) generation, and mitochondrial DNA (mtDNA) release. These events activated the cGAS-STING pathway, as evidenced by increased phosphorylation of STING, TBK1, and IRF-3, together with upregulation of IFN-γ and NF-κB, ultimately promoting immunogenic cell death. In 4T1 xenograft models, RL/BAI significantly inhibited primary tumor growth and lung metastasis, remodeled the pro-inflammatory tumor microenvironment by upregulating pro-inflammatory cytokines and promoting dendritic cell maturation, with no obvious systemic toxicity. Collectively, RL/BAI nanomicelles exert anti-TNBC effects through mitochondrial damage and cGAS-STING pathway activation, providing a novel natural biosurfactant-based nanomedicine strategy for TNBC treatment.