Toward Sustainable Crop Protection: Aqueous Dispersions of Biodegradable Particles with Tunable Release and Rainfastness

Fabrication of aqueous particulate dispersions of biodegradable cellulose esters (CEs) as efficient carriers of agrochemical active-ingredients (AIs) for foliar applications, is reported. The use of different ester substituent groups on CE permits modulation of particle morphology and size, from irregular shapes (<350 nm) to spheres (approximate to 1.1 mu m diameter), while maintaining stability as supported by minimal change in zeta potential and particle size over one year. Rainfastness is tested by simulating >50 mm h(-1) rainfall on coated banana and tomato leaves and silicon. Surface coverage loss as low as 9%, based on the nature of leaf and formulation, confirms the rainfastness of the formulations. Variation in the release kinetics of a model AI fluopyram from different CEs can be attributed to the particle morphology and the nature of binding between fluopyram and various CEs. Thermodynamic analysis demonstrates spontaneous binding between fluopyram and multiple sites of CEs, justifying its two-step release from CE particles. System functionalities are corroborated via in-vitro fungal inhibition assays demonstrating a 100% inhibition of the fungal growth. This "lab-to-leaf" approach of materials development involving fundamental insights and functional performance reveals CE dispersions are promising green agricultural formulations with the potential to impact a myriad of crops around the globe.