Green encapsulation of avobenzone in lignin microspheres: A promising approach for enhanced UV protection and photostability

Lignin, a natural macromolecule renowned for its exceptional UV-blocking capabilities, has gained attention as a promising material for encapsulating chemical sunscreens. However, the inherent heterogeneity and dark coloration of lignin have limited its application in the sunscreen industry. This study presents a novel approach to obtaining uniform and light-colored lignin through fractionation of alkali lignin using a green co-solvent system of dimethyl carbonate and ethanol. The processed lignin was then utilized to create regular-shaped microspheres via the emulsion solvent evaporation (ESE) method. By optimizing the preparation conditions, the chemical sunscreen avobenzone (AVO) was successfully encapsulated within these lignin microspheres, achieving an AVO loading capacity of up to 70 %. The resulting lignin microsphere-coated avobenzone (LM/AVO) microcapsules demonstrated broad-spectrum UV resistance and sustained photostability for up to 12 hours under continuous UV exposure. Additionally, the microcapsules exhibited robust antioxidant properties and negligible skin penetration, highlighting their excellent safety profile. These findings indicate the significant potential of lignin-based microcapsules for innovative and effective sunscreen formulations.