Colloidal lignin particles for Pickering emulsion stabilization: multifunctional properties and prospects for cosmetic applications

Lignin, the most abundant aromatic biopolymer on Earth, is abundantly found as a by-product of biomass processing industries. Lignin presents remarkable properties, including antioxidant, UV-blocking, thermal stability, and antimicrobial; thus being considered a valuable feedstock to replace synthetic and fossil-based resources. Colloidal lignin particles (CLPs) are a promising strategy to overcome technical barriers in lignin valorization and have attracted increasing interest to be applied as multifunctional ingredients into several fields, including agriculture, biomedical, construction, and more recently, cosmetics. For this latter, CLPs stand out as promising Pickering stabilizers, creating opportunities for the development of surfactant-free cosmetic formulations. This review provides a current state of lignin research, focusing on the production of CLPs and Pickering emulsions and the key factors influencing their formation and stability. Recent progress in CLPs-stabilized Pickering emulsions is thoroughly addressed. Furthermore, it highlights advances on the multifunctional attributes of CLPs, including antioxidant activity, UV shielding, and demonstrated safety for cosmetic applications. The review concludes by discussing current challenges and future research directions for advancing the use of CLPs as sustainable materials in cosmetic science.