Rational design of size-controlled corncob-derived lignin nanoparticles for antioxidant and UV shielding applications

In this study, we present a simple and reproducible strategy for the fabrication of self-assembled lignin nanoparticles (LNPs) using enzymatic lignin derived from corncob biomass. Despite the sustainable nature of lignin, its poor dispersibility, aggregation tendency, and limited formulation compatibility remain major challenges for practical cosmetic and UV-shielding applications. To address these limitations, LNPs were prepared via a solvent-exchange dialysis process driven by intermolecular interactions and solvent polarity shifts. The antioxidant activities of the prepared LNPs exhibited a concentration-dependent trend. The half maximal inhibitory concentration decreased from 115.55 μg/mL to 51.80 μg/mL with increasing lignin concentration, approaching the performance of the commercial antioxidant butylated hydroxytoluene. When LNPs were added to a cosmetic lotion formulation, they provided UV protection in both the UV-A and UV-B spectra. The UV-B protection rate increased from 61.6% (base cream) to 72.0%, 67.9%, and 71.9% with LNP contents of 1%, 5%, and 10%, respectively. Similarly, the UV-A protection rate increased from 26.4% to 40.8%, 36.3%, and 38.4%, representing improvements of 54.8%, 37.6%, and 45.5%, respectively. These results demonstrate that LNPs not only improve the dispersibility and functional performance of lignin-based formulations but also exhibit strong potential as sustainable and eco-friendly UV-shielding materials for cosmetic applications.