Eucalyptus Oil-Based Nanoemulsion: A Potent Green Nanowagon for Controlled Delivery of Emamectin Benzoate

Abstract

Formulating a biocompatible water-based pesticide and eliminating the use of toxic solvents encourage sustainable agriculture practices. In this study, a eucalyptus oil-in-water nanoemulsion (NEm) was employed as a green and biocompatible nanocarrier for the delivery of a water insoluble pesticide, emamectin benzoate (EB). NEm was prepared using low-energy emulsion phase inversion (EPI) and high-energy probe sonication (PS) with the help of food grade emulsifiers Tween 20 and Span 80. The effect of using a single or binary surfactant system and its effect on NEm droplet size and stability were investigated by measuring the change in droplet diameter for three months. The morphology, shape, and size of the NEm were assessed using high-resolution transmission electron microscopy, field emission scanning electron microscopy, and dynamic light scattering. Fourier transform infrared spectroscopy was employed to confirm the successful encapsulation of EB in the eucalyptus oil (EuO) core. During the investigation, the encapsulation efficiency of EPI NEm (91%) was higher than that of PS NEm (86%). The antiphotolysis and leaf adhesion ability of the EuO NEm was found to be better than those of free EB and the commercial EB formulation. Both NEms showed slow and sustained release compared to the commercial EB formulation, which shows a burst release. This implies EuO NEm behaves as a better pesticide formulation than free EB and its commercial analogue. However, EPI NEm with a higher encapsulation efficiency and a better release performance compared to those of PS NEm is considered a low-cost and easy-to-prepare nanoformulation. Thus, EB-loaded EuO NEm can be considered as a formulation that is greener, free of organic solvents, biocompatible, and easy to scale up for industrial application with promising sustainable agriculture development.