Antibacterial\nActivity of Ti₃C₂T_<i>x</i> MXene

Abstract

MXenes are a family\nof atomically thin, two-dimensional (2D) transition\nmetal carbides and carbonitrides with many attractive properties.\nTwo-dimensional Ti₃C₂T_<i>x</i> (MXene) has been recently explored for applications in water\ndesalination/purification membranes. A major success indicator for\nany water treatment membrane is the resistance to biofouling. To validate\nthis and to understand better the health and environmental impacts\nof the new 2D carbides, we investigated the antibacterial properties\nof single- and few-layer Ti₃C₂T_<i>x</i> MXene flakes in colloidal solution. The antibacterial\nproperties of Ti₃C₂T_<i>x</i> were tested against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) by using bacterial growth curves based on optical densities (OD)\nand colonies growth on agar nutritive plates. Ti₃C₂T_<i>x</i> shows a higher antibacterial\nefficiency toward both Gram-negative E. coli and Gram-positive B. subtilis compared\nwith graphene oxide (GO), which has been widely reported as an antibacterial\nagent. Concentration dependent antibacterial activity was observed\nand more than 98% bacterial cell viability loss was found at 200 μg/mL\nTi₃C₂T_<i>x</i> for both\nbacterial cells within 4 h of exposure, as confirmed by colony forming\nunit (CFU) and regrowth curve. Antibacterial mechanism investigation\nby scanning electron microscopy (SEM) and transmission electron microscopy\n(TEM) coupled with lactate dehydrogenase (LDH) release assay indicated\nthe damage to the cell membrane, which resulted in release of cytoplasmic\nmaterials from the bacterial cells. Reactive oxygen species (ROS)\ndependent and independent stress induction by Ti₃C₂T_<i>x</i> was investigated in two separate\nabiotic assays. MXenes are expected to be resistant to biofouling\nand offer bactericidal properties.