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

Abstract

Two-dimensional (2D) MXenes have emerged as a promising planar theranostic nanoplatform for versatile biomedical applications; but their <i>in vivo</i> 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. <b>Methods:</b> The <i>in situ</i> 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. <b>Results:</b> 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 <i>in vitro</i> and <i>in vivo</i> 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. <b>Conclusion:</b> 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.