Biomass-Based, Interface Tunable, and Dual-Responsive Pickering Emulsions for Smart Release of Pesticides

The extremely low utilization efficiency of pesticides has driven people to develop low-cost, sustainable, and smart delivery systems. Pickering emulsion (PE) derived from biomass is an attractive candidate. However, the stability of PE is insufficient, and pesticide release from PE can be hardly tuned. Herein, a facile in situ PE modification strategy to construct a stable and high-performance pesticide delivery system from biomass resources is reported. In this process, PE stabilized by alkali lignin nanoparticles is initially prepared, and subsequently, opposite-charged chitosan (CH), and sodium lignosulfonate (SL) are alternatively deposited onto the PE interface through layer-by-layer assembly to form a microcapsule system (CH+SL)n@PE. The resulting biomass-based microcapsules show improved stability, high encapsulation efficiency, and super UV protection to avermectin (AVM), a hydrophobic and photo-sensitive pesticide. Furthermore, the shell thickness of microcapsules can be finely tuned by controlling the deposited CH+SL layers, which enable (CH+SL)n@PE to have adjustable release behaviors. (CH+SL)20@PE prolongs the half-life of AVM under UV irradiation by 5.0-fold. Moreover, (CH+SL)n@PE exhibits pH and laccase dual responsiveness, which is beneficial to the targeted release of AVM in vivo. Therefore, the current PE modification strategy can provide an eco-friendly, low-cost, and smart system for precise delivery of pesticides.