No abstract

Current trends in the field of MXenes emphasize the importance of controlling their surface features for successful application in biotechnological areas. The ability to stabilize the surface properties of MXenes has been demonstrated here through surface charge engineering. It was thus determined how changing the surface charges of two-dimensional (2D) Ti3C2 MXene phase flakes using cationic polymeric poly-L-lysine (PLL) molecules affects the colloidal and biological properties of the resulting hybrid 2D nanomaterial. Electrostatic adsorption of PLL on the surface of delaminated 2D Ti3C2 flakes occurs efficiently, leads to changing an MXene’s negative surface charge toward a positive value, which can also be effectively managed through pH changes. Analysis of bioactive properties revealed additional antibacterial functionality of the developed 2D Ti3C2/PLL MXene flakes concerning Escherichia. coli Gram-negative bacteria cells. A reduction of two orders of magnitude of viable cells was achieved at a concentration of 200 mg L−1. The in vitro analysis also showed lowered toxicity in the concentration range up to 375 mg L−1. The presented study demonstrates a feasible approach to control surface properties of 2D Ti3C2 MXene flakes through surface charge engineering which was also verified in vitro for usage in biotechnology or nanomedicine applications.

There are several problems that need to be overcome to enable smooth and sustainable clinical translation of the MXene materials, including hard controllable surface chemistry. In this study, we show for the first time that, by using surface modification with poly-l-lysine (PLL), it is possible to completely invert the highly negative surface charge of the 2D niobium carbide MXenes (viz., Nb2C and Nb4C3) toward a highly positive value. Switching the surface charge of MXenes results in obtaining important biological effects in vitro such as targeting of malignant cells and inducing cell cycle arrest at the G0/G1 phase and triggering apoptosis, i.e., programmed cell deaththe most desirable effect for designing anticancer nanodrugs, which should directly target the cells’ physiology instead of generating direct toxicity. In addition, both 2D Nb2C/PLL and Nb4C3/PLL MXenes showed significant adjustment of their biocompatibilities in relation to normal skin cells. The obtained results suggest that Nb-MXenes can be used as scavengers for the reactive oxygen species (ROS). This study formulates an important step toward further development of MXene-based nanotherapies and strategies for cancer cell elimination in relation to standard therapeutic procedures currently being developed for these materials.

Point-of-use (POU) water treatment systems and devices play an essential role in limited access to sanitary safe water resources. The filtering materials applied in POU systems must effectively eliminate contaminants, be readily produced and stable, and avoid secondary contamination of the treated water. We report an innovative, 2D Ti3C2/Al2O3/Ag/Cu nanocomposite-modified filtration material with the application potential for POU water treatment. The material is characterized by improved filtration velocity relative to an unmodified reference material, effective elimination of microorganisms, and self-disinfecting potential, which afforded the collection of 99.6% of bacteria in the filter. The effect was obtained with nanocomposite levels as low as 1%. Surface oxidation of the modified material increased its antimicrobial efficiency. No secondary release of the nanocomposites into the filtrate was observed and confirmed the stability of the material and its suitability for practical application in water treatment.