Lignin-based nanozyme as a free radical scavenger for UV induced DNA protection

Constructing metal-N_x centers using eco-friendly green natural ligands represents a viable strategy to enhance the sustainability of nanozymes. Herein, a Zn-doped aminated lignin (Zn-AL) nanozyme with superoxide dismutase (SOD)-like activity was synthesized. The resulting Zn-N_x centered nanozyme was achieved through the epoxy-amination of industrial alkali lignin to improve its coordination capability to zinc ions, which could effectively scavenge multiple reactive oxygen species (ROS), including superoxide anions (·O₂^-), ABTS radicals, and hydroxyl radicals (·OH). Notably, the Zn-AL exhibited exceptional thermal stability, maintaining over 90 % activity across a temperature range of 20-80 °C, and retained over 80 % of its initial activity after 5 recycles. Moreover, at a low concentration of 0.25 mg mL^-1, Zn-AL protected calf thymus DNA from UV-induced oxidative damage after 120-min irradiation. These findings highlight that Zn-AL is a robust, sustainable, and efficient nanozyme holding promise for applications in managing oxidative stress.