Multilayered stable 2D nano-sheets of Ti₂NT_x MXene: synthesis, characterization, and anticancer activity

The biological activity of MXenes has been studied for several years because of their potential biomedical applications; however, investigations have so far been limited to 2D titanium carbides. Although monolayered Ti₂NT_x MXene has been expected to have biological activity, experimental studies revealed significant difficulties due to obstacles to its synthesis, its low stability and its susceptibility to oxidation and decomposition.

In this paper, we report our theoretical calculations showing the higher likelihood of forming multilayered Ti₂NT_x structures during the preparation process in comparison to single-layered structures. As a result of our experimental work, we successfully synthesized multilayered Ti₂NT_x MXene that was suitable for biological studies by the etching of the Ti₂AlN MAX phase and further delamination. The biocompatibility of Ti₂NT_x MXene was evaluated in vitro towards human skin malignant melanoma cells, human immortalized keratinocytes, human breast cancer cells, and normal human mammary epithelial cells. Additionally, the potential mode of action of 2D Ti₂NT_x was investigated using reactive oxygen tests as well as SEM observations. Our results indicated that multilayered 2D sheets of Ti₂NT_x showed higher toxicity towards cancerous cell lines in comparison to normal ones. The decrease in cell viabilities was dose-dependent. The generation of reactive oxygen species as well as the internalization of the 2D sheets play a decisive role in the mechanisms of toxicity.

We have shown that 2D Ti₂NT_x in the form of multilayered nanoflakes exhibits fair stability and can be used for in vitro studies. These results show promise for its future applications in biotechnology and nanomedicine.