Manipulation and elimination of circulating tumor cells using multi-responsive nanosheet for malignant tumor therapy

Tumor recurrence caused by metastasis is a major cause of death for patients. Thus, a strategy to manipulate the circulating tumor cells (CTCs, initiators of tumor metastasis ) and eliminate them along with the primary tumor has significant clinical significance for malignant tumor therapy. In this study, a magnet-NIR-pH multi-responsive nanosheet (Fe₃O₄@SiO₂-GO-PEG-FA/AMP-DOX, FGPFAD) was fabricated to capture CTCs in circulation, then magnetically transport them to the primary tumor, and finally perform NIR-dependent photothermal therapy as well as acidic-environment-triggered chemotherapy to destroy both the CTCs and the primary tumor. The FGPFAD nanosheet consists of silica-coated ferroferric oxide nanoparticles (Fe₃O₄@SiO₂, magnetic targeting agent), graphene oxide (GO, photothermal therapy agent), polyethylene glycol (PEG, antifouling agent for sustained circulation), folic acid (FA, capturer of CTCs) and antimicrobial-peptide-conjugated doxorubicin (AMP-DOX, agent for chemotherapy), in which the AMP-DOX was bound to the FGPFAD nanosheet via a cleavable Schiff base to achieve acidic-environment-triggered drug release for tumor-specific chemotherapy. Both in vitro and in vivo results indicated that the effective capture and magnetically guided transfer of CTCs to the primary tumor, as well as the multimodal tumor extermination performed by our FGPFAD nanosheet, significantly inhibited the primary tumor and its metastasis.