Preparation and Properties of Fomesafen@SiO₂-Starch Microspheres for Herbicide-Controlled Release

Fomesafen serves as a widely employed selective herbicide for addressing broadleaf weeds, but the short duration of efficacy limits utilization efficiency. There exists an exigent requirement to extend its efficacy through controlled release mechanisms. Fomesafen@SiO2-starch microspheres with α-amylase responsiveness were synthesized through the direct binding of drug-loaded silica microspheres and modified starch. This fabrication method capitalizes on the enzymatic degradation potential of the outer starch layer by amylase. In contrast with earlier analogous structures that exhibited inferior drug loading efficacy, the prepared fomesafen@SiO2-starch microspheres demonstrated a significantly enhanced drug loading capacity of up to 35.7%. Furthermore, in comparison to fomesafen technical, the prepared fomesafen@SiO2-starch microspheres exhibited a notable capacity to mitigate the photolysis of fomesafen through the utilization of the starch outer layer. Additionally, the fomesafen@SiO2-starch microspheres demonstrated favorable wettability and adhesive properties. At the recommended dosage, the herbicidal efficacy of fomesafen@SiO2-starch microspheres against Brassica napus L. and Portulaca oleracea L. over 14 days was observed to be comparable to that of the fomesafen technical, concurrently exhibiting a degree of sustained release. These findings underscore the potential of microspheres in regulating the release of fomesafen, thereby presenting a promising avenue for the development of sustainable drug delivery systems in agriculture.