Electrospun Polymer Nanofibers as Seed Coatings for Crop Protection

Abstract

Ineffective delivery of pesticides leads to multiple application cycles of active ingredients (AIs), resulting in increased cost while endangering the environment via soil, water, and air contamination. Herein, we present a facile approach for localized delivery of pesticides by coating seeds with electrospun cellulose diacetate (CDA) nanofibers containing abamectin or fluopyram as model AIs. CDA is used as the polymer of choice because of its good electrospinnability, low water solubility, and eventual biodegradability. Nanofibrous coatings are directly electrospun onto soybean seeds and show no deleterious effects on seed germination regardless of coating thickness and uniformity. Water dissolution studies show that nanofibers maintain their integrity for over 2 weeks, a necessary characteristic to make this approach effective. AI release studies display a slow and sustained release of both abamectin and fluopyram from the nanofibers, with abamectin exhibiting a slower release because of its more hydrophobic nature and possibly stronger interaction with CDA. Functional performance, tested using fluopyram-loaded nanofibers in an in vitro fungal assay against the plant pathogen Alternaria lineariae, consistently inhibits fungal growth. The sustained release profile taken together with moisture stability suggests that nanofibrous seed coatings have a strong potential as an alternative platform to control plant pathogens such as nematodes and fungi.