UV-Blocking Properties of Nanolignin

Lignin, the second-most abundant natural biopolymer, has traditionally been regarded as a low-value by-product of the pulp and paper industry. However, research over the past decade has consistently demonstrated the importance and potential of lignin across various industries. The abundant phenolic units in lignin’s structure, particularly the phenolic hydroxyl, methoxyl, and conjugated double bonds, contribute to its antioxidant, antimicrobial and UV-protective activity. In recent years, several methods have been developed to synthesize lignin nanomaterials, including the top-down, bottom-up and sustainable approaches. Nanolignins are lignin particles or assemblies designed at the nanoscale, with sizes ranging from 10 nm to 500 nm. At this nanoscale, surface area, dispersibility, and interfacial behavior of lignin are greatly enhanced, leading to improvements in various functional applications. The UV-protective property of nanolignin has been well established and utilized in the development of various functional products, including cosmetics, packaging, and textile and polymer composites, among others. Compared to conventional UV blockers, nanolignin provides superior broad-spectrum UV protection (UVA/UVB) and additional antioxidant properties. It imparts UV protection through a combination of absorption and partial scattering, enabled by its aromatic, phenolic, and conjugated functional groups. Also, nanolignin demonstrates better biocompatibility and environmental sustainability, with a lower risk of bioaccumulation, making it a promising, safer, and eco-friendly alternative for applications as a UV blocker in sunscreens, packaging, coatings, and biomedical materials.