Valorization of lignin through zein Co-assembly into green nanopesticides for photostable, sustained-release abamectin delivery with insecticidal efficacy and biosafety.

Industrial alkali lignin is an abundant aromatic biological macromolecule with intrinsic UV shielding ability, but its structural heterogeneity and aqueous self-aggregation limit its use as a stable carrier matrix. Herein, industrial alkali lignin was valorized through zein regulated co-assembly to construct surfactant free hybrid biological macromolecular nanocapsules (LZNP@Abm) for abamectin (Abm) delivery. The composite macromolecular matrix afforded excellent colloidal stability and a loading capacity of 79.22%, and LZNP@Abm retained 74.94% Abm after 72 h of UV irradiation, effectively mitigating photolytic degradation. By integrating lignin derived UV shielding with zein mediated interfacial stabilization and pH and temperature responsive gating, LZNP@Abm suppressed release, with only 34.18% release after 180 h under weakly acidic leaf surface and soil conditions, while accelerating release at pH 9 and 35 °C, conditions relevant to alkaline and warm lepidopteran larval midguts. Molecular dynamics and density functional theory analyses identified key zein residues, including asparagine, serine, and proline, that enhanced Abm binding through cooperative hydrogen bonding and van der Waals interactions. Improved foliar wettability and liquid retention further promoted leaf deposition and reduced potential non-target pesticide loss. LZNP@Abm achieved 5.7-23.5-fold reductions in LC50 against Spodoptera frugiperda and complete mortality of S. litura, restored seed germination to 85.56%, and maintained earthworm survival at 83.33 to 96.67%. This work demonstrates a mechanism informed biopolymer carrier strategy for converting industrial lignin into a functional pesticide delivery platform with photoprotection, controlled release, and improved biosafety.