Therapeutic mesopore construction on 2D Nb2C MXenes for targeted and enhanced chemo-photothermal cancer therapy in NIR-II biowindow.

Two-dimensional (2D) MXenes have emerged as a promising planar theranostic nanoplatform for versatile biomedical applications; but their in vivo behavior and performance has been severely influenced and hindered by a lack of necessary surface chemistry for adequate surface engineering. To solve this critical issue, this work employs versatile sol-gel chemistry for the construction of a unique "therapeutic mesopore" layer onto the surface of 2D niobium carbide (Nb2C) MXene. Methods: The in situ self-assembled mesopore-making agent (cetanecyltrimethylammonium chloride, in this case) was kept within the mesopores for efficient chemotherapy. The abundant surface saline chemistry of mesoporous silica-coated Nb2C MXene was further adopted for stepwise surface engineering including PEGylation and conjugation with cyclic arginine-glycine-aspartic pentapeptide c(RGDyC) for targeted tumor accumulation. Results: 2D Nb2C MXenes were chosen based on their photothermal conversion capability (28.6%) in the near infrared (NIR)-II biowindow (1064 nm) for enhanced photothermal hyperthermia. Systematic in vitro and in vivo assessments demonstrate targeted and enhanced chemotherapy and photothermal hyperthermia of cancer (U87 cancer cell line and corresponding tumor xenograft; inhibition efficiency: 92.37%) in the NIR-II biowindow by these mesopore-coated 2D Nb2C MXenes. Conclusion: This work not only significantly broadens the biomedical applications of 2D Nb2C MXene for enhanced cancer therapy, but also provides an efficient strategy for surface engineering of 2D MXenes to satisfy versatile application requirements.