RESUMEN
MXenes is an emerging two-dimensional (2D) material, which was composed of layered transition metal carbides and/or nitrides, have attracted enormous attention in the past decade since their innovative discovery by Gogotsi and Barsoum in 2011. The general formula of MXenes is Mn+1XnTx (n=1-4), where M represents transition metal elements (such as Ti, Nb, Ta, etc.), X represents carbon and/or nitrogen, and Tx represents surface terminations (such as —OH, —F, =O, etc.). In recent years, MXenes have been widely applied in the biological field due to their high biocompatibility, abundant surface groups, good conductivity and photothermal properties. Due to the strong absorption of laser in the near infrared region, strong X-ray attenuation ability and surface easily modified by various molecules or nanoparticles, MXenes have been used as photothermal agents and contrast agents in the tumor therapy and tumor diagnosis. This paper reviews the application of MXenes and MXenes-based composites in tumor therapy and active targeting tumor therapy. According to the modal of action on tumor cells, it was divided into monotherapy, bimodal therapy and trimodal therapy. Among them, the monotherapy mainly used the photothermal properties of MXenes for photothermal therapy, studies have found that MXenes QDs can be used for chemodynamic therapy. In addition, sonodynamic therapy can also be achieved by loading the sonosensitizers on the surface of MXenes. Bimodal therapy and trimodal therapy are mainly used to load anticancer drugs, photosensitizers, metal particles and other substances on the surface of MXenes to achieve combination therapy. In contrast to the limited treatment efficacy and possible side effects arising from monotherapy, the development of bimodal therapy and trimodal therapy may harbor the collective merits of respective individual treatments and give rise to much higher anticancer efficacy at lower dosage of therapeutic agents administered, thus avoiding high-dose-induced side effects. The combined use of multiple treatments displayed superior advantages over monotherapy in producing an improved therapy outcome. According to the modal of entry into tumor cells, it was divided into passive targeting and active targeting. Active targeting therapy was mainly divided into homologous targeting therapy and targeting agents targeting therapy. The strategy of homologous targeting therapy was to coat MXenes with tumor cell membrane and increased the uptake of MXenes by tumor cells. Targeting agents targeting therapy used targeting agents to specifically bind to the receptors on the surface of tumor cells, subsequently, the precise uptake of MXenes by tumor cells was achieved. Finally, the current challenges and future development trends of MXenes in preparation technology and tumor therapy are discussed.