Quaternary ammonium carbon dots for membrane perforation-immunity synergistic therapy against drug-resistant cancer metastasis

Multidrug resistance and invasive metastasis constitute pivotal clinical bottlenecks that severely compromise curative outcomes of malignant tumors. Conventional chemotherapy and immunotherapy frequently fail to achieve satisfactory efficacy due to drug resistance barriers and tumor immune escape. Herein, a hyaluronic acid‑cinnamaldehyde Schiff base micelle nanoplatform loading quaternary ammonium‑modified carbon dots (HACA@QASCDs) is rationally constructed, which achieves targeted killing of drug‑resistant tumor cells, remodeling of immunosuppressive microenvironments, and inhibition of distant metastasis via a sequential cascade of irreversible membrane perforation, mitochondria‑dependent apoptosis, and immunogenic cell death (ICD). HACA@QASCDs actively accumulate in drug‑resistant CT26 (DR‑CT26) cells through HA‑CD44 recognition and enable pH‑triggered QASCDs release in acidic tumor microenvironments. The liberated QASCDs elicit irreversible membrane perforation, leading to lactate dehydrogenase leakage, disrupted calcium homeostasis, mitochondrial depolarization, and subsequent intrinsic apoptosis. Such membrane damage simultaneously ignites ICD, and the released damage‑associated molecular patterns effectively drive dendritic cell maturation and M2‑to‑M1 macrophage polarization. In vivo evaluations in bilateral syngeneic tumor models reveal that HACA@QASCDs alone yields 54.2% primary tumor inhibition and 28.6% distant tumor inhibition. Upon combination with αPD‑L1, the distant tumor inhibition rate is markedly elevated to 68.7%. By integrating membrane perforation‑mediated direct cytotoxicity and ICD‑evoked immune activation, HACA@QASCDs offers a highly potent and clinically translatable synergistic strategy to surmount tumor multidrug resistance and block invasive metastasis.