Lignin represents a potentially significant natural sunscreen alternative due to its good UV-absorbing ability, but its poor UVA absorption and dark colour are still obstacles. Numerous methods have been developed to whiten the colour of lignin, mainly including aromatic ring interruption and hydroxyl group blocking. However, these complicated procedures would weaken the UV-blocking and radical scavenging abilities. Here, we develop a strategy for the valorization of lignin in sunscreen to overcome their drawbacks by the in situ self-assembly of the natural light-coloured peanut hull lignin with the commercially available UV-protectant Ecamsule·2Na to obtain peanut hull lignin/Ecamsule·2Na hollow nanoparticles (P/E LNPs). The results show that the sun protection factor (SPF) value increased from 20 to 27, and the antioxidant capacity increased exponentially with a scavenging rate of up to 82 % at the extremely low dosage up to 0.1 mg/L of P/E LNPs. In addition, their good biocompatibility and safety were further confirmed by in vitro cytotoxicity analysis. In summary, we have successfully prepared a safe, broad-spectrum, light-coloured, and highly antioxidant, peanut hull lignin-based sunscreen that avoids any complicated chemical modifications to meet the commercial sunscreen requirement and also provides a new solution for the valorization of lignin from the vast amount of waste fruit hulls.
Keywords: Broad-spectrum UV protection; Hollow nanoparticles; Lignin-based sunscreen; Peanut hull.
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