Esterified Lignin\nNanoparticles for Targeted Chemical\nDelivery in Plant Protection

There is a growing demand for biobased functional materials\nthat\ncan ensure targeted pesticide delivery and minimize active ingredient\nloss in the agricultural sector. In this work, we demonstrated the\nuse of esterified lignin nanoparticles (ELNPs) as carriers and controlled-release\nagents of hydrophobic compounds. Curcumin was selected as a hydrophobic\nmodel compound and was incorporated during ELNP fabrication with entrapment\nefficiencies exceeding 95%. ELNPs presented a sustained release of\ncurcumin over 60 days in an oil medium, with a tunable release rate\ndependent on the lignin-to-curcumin mass ratio. The ELNPs showed a\nstrong adhesion interaction with the hydrophobic wax surface. Quartz\ncrystal microbalance with dissipation monitoring (QCM-D) and atomic\nforce microscopy (AFM) analysis suggested that the ELNPs permeated\ninto the wax layer, potentially preventing pesticide loss due to runoff\nor rainwater leaching. Rapidly decreasing contact angles between a\ndroplet containing an aqueous dispersion of the ELNPs and a fresh\nleaf surface provided further evidence of a favorable interaction\nbetween the two. Overall, our results portray ELNPs as promising biobased\nnanoparticulate systems for pesticide delivery to hydrophobic plant\nsurfaces.