Ti₃C₂ nanosheets with broad-spectrum antioxidant activity for cytoprotection against oxidative stress

Redox regulation in biological systems represents a fascinating method for treatment and prevention of oxidative stress induced diseases. The key and difficult point is to find ideal materials with excellent antioxidant capability and good biocompatibility. To this end, ultra-thin two-dimensional MXene (Ti₃C₂) nanosheets (NSs) were investigated for their antioxidant capability. It is found that Ti₃C₂ NSs can scavenge efficiently reactive oxygen and nitrogen species (˙OH, H₂O₂, and ˙NO), ABTS⁺˙ and DPPH˙ free radicals in a concentration dependent manner, showing broad-spectrum antioxidant activities. Ti₃C₂ NSs exhibit higher antioxidant activity and broader antioxidant capability than natural antioxidant molecules. The significant role of PEG modified Ti₃C₂ with good stability in preventing cell damage against oxidative stress was demonstrated. Upon treatment of H₂O₂ induced oxidative stress with Ti₃C₂, the intracellular ROS level decreases and the cell survival rate increases significantly. An antioxidant mechanism based on gradient oxidation was proposed to account for the superior antioxidant activity of Ti₃C₂. Our result proves that ultra-thin MXenes as antioxidants have great potential in preventing oxidative stress caused biological damage.