Boosting the peroxidase-like activity of Pt nanozymes by a synergistic effect of Ti3C2 nanosheets for dual mechanism detection.

Nanozymes show great promise in bioanalysis and therapeutics, which largely rely on high catalytic efficiency and selectivity. Inspired by the interfacial electronic interaction between noble metals and transition metal carbides, Pt nanozymes are modified with Ti3C2 MXene nanosheets to construct Ti3C2/Pt hybrids with synergistically enhanced catalytic activity. Although Ti3C2 does not have oxidase and peroxidase-like activity, it can greatly selectively enhance the peroxidase-like activity of Pt nanozymes. Near-infrared irradiation can further increase specifically the peroxidase-like activity of Ti3C2/Pt. The optimal peroxidase-like activity of Ti3C2/Pt is 6 times higher than Pt in the dark and 7.9 times higher than Pt under illumination. This catalytic enhancement is attributed to the interplay of the strong interfacial electron effect and unique photothermal effect of Ti3C2. Using the superior peroxidase-like activity of Ti3C2/Pt, dual mechanism colorimetric methods based on cascade reaction and inhibitory effect are developed for specific detection of glucose and glutathione with a limit of detection of 1.0 µM and 0.0089 µM, respectively. Our work provides an effective means to improve the catalytic activity and selectivity of nanozymes by introduction of an ideal supporter, which will be of value for the design of efficient nanozymes.

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.