Iron-doped carbon dots nanozyme scavenged reactive oxygen species system for inhibiting effectively the uptake of arsenic in lettuce

The plants were suffered from oxidative damage caused by arsenic stress, as a major environmental challenge posing a serious threat to both yield and quality of crops. To tackle this challenge, herein, iron-doped carbon dots (Fe-CDs) nanozyme, synthesized via one-step hydrothermal method, has been reported as a highly active reactive oxygen species targeted (ROS-targeted) scavenger. It effectively alleviated arsenic-induced oxidative stress in lettuce. Fe-CDs nanozyme possessed POD-like, CAT-like, and SOD-like enzymes activity, effectively scavenging a variety of ROS (H₂O₂, O₂^•− and ·OH). Electrochemical tests fully validated that its excellent enzymatic activity was attributed to the acceleration of electron transfer and enhancement of catalytic efficiency. Furthermore, theoretical calculations confirmed that iron ions as the catalyst site enhanced the adsorption of Fe-CDs to H₂O₂ (−0.666 eV) better that of CDs (−0.171 eV), accelerating Fe-CDs nanozyme ROS-targeted scavenging. Based on this, the finding from using Fe-CDs to mitigate arsenic stress in lettuce revealed Fe-CDs nanozyme enabled to effectively exert the role of antioxidant nanozyme to clear excessive accumulated ROS in lettuce. This has successfully reduced the uptake of arsenic by lettuce (decreased arsenic content to 34.7 %), thereby enhancing the stress resistance of lettuce. Laser confocal image have revealed a reduction of 36 % in the average fluorescence intensity of ROS in leaves subsequent Fe-CDs treatment. It was observable that Fe-CDs could be used as a potential antioxidant in ROS scavenging system, via a nanozyme catalytic strategy. The accumulated ROS in biological systems was down-regulated, reducing the abiotic stress in crops consequently. This innovative strategy of designing a nanomaterial specifically engineered to targeted-scavenge the ROS system paves a novel avenue for effectively inhibiting plants’ uptake of arsenic.