Catechyl lignin enhances self-assembly for Pickering emulsion stabilization and the controlled-release application

Lignin structure significantly affects the self-assembly ability into lignin nanoparticles (LNPs) and their properties for the specific applications. Herein, several lignin oligomers with distinctive chemical structures were extracted from the typical biomasses and self-assembled into LNPs, which were further used to stabilize Pickering emulsion. The linearly arranged catechyl unit and the abundant phenolic hydroxyl groups in the castor seed coats-derived lignin oligomers would promote their π-π stacking and hydrogen bonding interactions for the self-assembly. Associating with further fractionation of the catechyl lignin, the hydrophilic part with large molecular weight were separated, and self-assembled into small and uniform LNPs. The catechyl unit in the catechyl lignin self-assembled LNPs endowed high hydrophilicity of the LNPs surface with rich negative charge. The uniform LNPs could stabilize Pickering emulsion with smaller vacuoles, which showed high stability maintaining at least 15 days. Subsequently, the LNPs-stabilized Pickering emulsion was applied for curcumin encapsulation, improving its storage and controllable release. This study may contribute to the application of curcumin in food and drug formulations, increase the utilization efficiency of pharmaceutical molecules and reduce their usages, creating economic and alleviating environmental issue.