ZnO/Dealkali Lignin Composite Nanosheet for Antiultraviolet and Antioxidant Applications

Ultraviolet (UV) radiation is a primary culprit in skin aging and cancer development. Inorganic UV filters, including ZnO and TiO2, are typical antiultraviolet agents in sunscreen, but they lack antioxidant activity for scavenging reactive oxygen species (ROS). Inspired by the UV shielding mechanism of plant cell wall lamellar structures, a 2D/2D ZnO/dealkali lignin (DL) nanosheet composite was prepared using an in situ templating method. Various mass ratios of DL to ZnCl2 were adjusted to investigate the effect of DL addition on UV shielding. The results show that ZnO/DL-1.5% effectively shields ultraviolet B (UVB) and ultraviolet A (UVA) radiation due to the hydrogen bonding interaction between ZnO and DL, rendering the exposure of the (002) plane of ZnO, which increases the scattering and absorption of photons. Additionally, the ZnO/DL nanosheet composite scavenges excessive reactive nitrogen species and ROS at low concentrations, as the phenolic hydroxyl groups in DL donate electrons to neutralize free radicals, thereby terminating radical chain reactions. This ZnO/DL nanosheet composite, with antiultraviolet and antioxidant functions, can be considered a promising and safe ingredient for sunscreen cream.