Fabrication of Polydopamine-Coated High-Entropy MXene Nanosheets for Targeted Photothermal Anticancer Therapy

Transition metal carbides, nitrides, and carbonitrides (MXenes) have emerged as a promising class of 2D materials that can be used for various applications. Recently, a new form of high-entropy MXenes has been reported, which contains an increased number of elemental species that can increase the configurational entropy and reduce the Gibbs free energy. The unique structure and composition lead to a range of intriguing and tunable characteristics. Herein, the fabrication of high-entropy MXene TiVNbMoC₃T_x (T = surface terminations) with a layer of polydopamine is reported, followed by immobilization of a phthalocyanine-based fluorophore for imaging and the peptide sequence QRHKPREGGGSC for targeting the epidermal growth factor receptor (EGFR) overexpressed in cancer cells. The resulting nanocomposite exhibits high biocompatibility and superior photothermal property. Upon laser irradiation at 808 nm, the light-to-heat conversion efficiency is up to 56.1%, which is significantly higher than that of conventional 2D materials. In vitro studies show that these nanosheets could be internalized selectively into EGFR-positive cancer cells and effectively eliminate these cells mainly through photothermal-induced apoptosis. Using 4T1 tumor-bearing mice as an animal model, the nanosheets could accumulate at the tumor and effectively eradicate the tumor upon laser irradiation without causing noticeable adverse effects to the mice.