Size and chemical structure impact of lignin biopolymer over performances of next-generation sunscreens

In recent years, growing concerns about the harmful effects of synthetic UV filters on both humans and the environment raised awareness about natural sun blockers.Lignin, considerate as the most abundant aromatic renewable polymer on earth, emerges as a strong contender for the development of next-generation sunscreens due to its inherent UV ray's absorbance properties, as well as its distinctive qualities as a green, biodegradable, and biocompatible material.Furthermore, lignin current limitations such as dark color and poor dispersity can potentially be overcome with particle size reduction to nano scale, paving the way for improved UV protection and enhanced formulation.In this study, 100 -200 nm lignin nanoparticles (LNPs) were eco-friendly prepared from various biomass waste with anti-solvent precipitation method using water and ethanol.Initially, pure lignin macroparticles (LMPs) were extracted from beech, spruce and wheat using ethanol-Organosolv treatment (OL) in opposition to sulfur-rich kraft lignin (KL).We prepared sunscreen lotions from these LMPs and LNPs at different concentrations (1, 5 and 10 wt%) showing distinct UV-shielding properties depending on biomass type and particles size.Indeed, our results showed that for same lignin, transition from macro to nano scale multiplied sunscreens sun protection factor (SPF) and efficacity between 2.5 and 6.As an example for wheat straw, SPF was improved from 7.5 to 42 for same LMPs and LNPs 5 wt%, generating high quality green sunscreens.This study confirms that lignin polymer, often erroneously regarded as waste, can significantly contribute to the development of green and innovative valorizations in alignment with the principles of green chemistry. of commercial SPF 10 sunscreen mixed with 5 wt% of LMPs; UV transmittance of pure cream mixed different amount of LMPs and LNPs.