Green, biocompatible, and biodegradable antioxidants represent a milestone in cosmetic and cosmeceutical applications. Lignin is the most abundant polyphenol in nature, recovered as a low-cost waste from the pulp and paper industry and biorefinery. This polymer is characterized by beneficial physical and chemical properties which are improved at the nanoscale level due to the emergence of antioxidant and UV shielding activities. Here we review the use of lignin nanoparticles in cosmetic and cosmeceutical applications, focusing on sunscreen and antiaging formulations. Advances in the technology for the preparation of lignin nanoparticles are described highlighting structure activity relationships.

Microcapsules and nanocapsules based on the contemporary presence of sulfonate lignin and tannic acid have been prepared by the layer-by-layer procedure, using MnCO or organosolv lignin as core templates, and polydiallyldimethylammonium chloride or chitosan as positive charged supporting layers. Nanocapsules and microcapsules of mixed polyphenols showed antioxidant activity, UV-shielding properties, and electrochemical responsiveness, higher than that in homopolymer nanocapsule counterparts and of the native polyphenols, suggesting the presence of synergistic effects between the two components. The presence of UV-visible bathochromic shift suggested the formation of J-aggregates characterized by an orientation of the adjacent phenolic rings parallel to the longitudinal direction of the layer, with a head-to-tail like arrangement. Moreover, nanocapsules of mixed polyphenols showed an aggregation state higher than that observed in references, the specific morphology of their surface being dependent on the structural arrangement of the different components.

Sustainable catalysts for the oxidation of phenol derivatives under environmentally friendly conditions were prepared by the functionalization of lignin nanoparticles with tyrosinase. Lignin, the most abundant polyphenol in nature, is the main byproduct in the pulp and paper manufacturing industry and biorefinery. Tyrosinase has been immobilized by direct adsorption, encapsulation, and layer-by-layer deposition, with or without glutaraldehyde reticulation. Lignin nanoparticles were found to be stable to the tyrosinase activity. After the enzyme immobilization, they showed a moderate to high catalytic effect in the synthesis of catechol derivatives, with the efficacy of the catalyst being dependent on the specific immobilization procedures.

Lignin nanoparticles as functional renewable nanoplatform for the immobilization of cascade process in colorimetric biosensing of β-d-glucose.