Interfacial Properties of Surface-Modified Lignin Nanoparticles

The interfacial properties of surface-modified lignin nanoparticles (LNPs) through the adsorption of various compounds or grafting of different ligands dictate their uses and potential applications in life sciences. In this study, we investigate softwood (Lignoboost lignin, LB) and hardwood (Birch lignin, BB) LNPs and compare them to LNPs treated with laccase-induced oxidation, hemicellulose (galactoglucomannan (GGM) and glucuronoxylan (GX)) adsorption, and laccase-induced hemicellulose adsorption. Then, we compare the interfacial properties of the obtained particles through contact angle and interfacial tension analyses and compare these to the stability of their emulsions. The study reveals that hemicellulose adsorption increases the hydrophilicity of LNPs, except for GX, and laccase-induced hemicellulose adsorption increases the hydrophobicity of particles. The unique features of functionalized BB-LNPs with GX are that they adsorb rapidly at the interface, show increased hydrophobicity, and avoid aggregation in the emulsion. The roles of hemicellulose adsorption and laccase-induced hemicellulose adsorption are discussed by considering the interfacial tension and contact angle for emulsification. These findings lay the groundwork for comprehending the role of hemicellulose in surface-modified LNPs in interfacial stabilization and expand their potential uses in food, pharmaceuticals, and biomedical sciences.