Preparation and Properties of Photoresponsive Pendimethalin@Silica-cinnamamide/γ-CD Microspheres for Pesticide Controlled Release

Photocontrolled pesticide delivery systems have broad prospects for application in agriculture. Here, a novel photoresponsive herbicide delivery system was fabricated by functionalizing silica microsphere surfaces with cinnamamide and encapsulating the silica-cinnamamide with gamma-cyclodextrin (gamma-CD) to form a double-layered microsphere shell loaded with pendimethalin (pendimethalin@silica-cinnamamide/gamma-CD). The microspheres showed remarkable loading capacity for pendimethalin (approximately 30.25% w/w) and displayed excellent photoresponsiveness and controlled release. The cumulative drug release rate exceeded 80% over 72 h under UV or sunlight irradiation. The herbicidal activity of the microspheres against Echinochloa crusgalli (L.) Beauv. was almost the same as that of pendimethalin under UV or sunlight. A bioactivity survey confirmed that the pendimethalin@silica-cinnamamide/gamma-CD microspheres exhibited longer duration weed control than commercial pendimethalin. Allium cepa chromosomal aberration assays demonstrated that the microspheres showed lower genotoxicity than pendimethalin. These advantages indicate that pendimethalin@silica-cinnamamide/gamma-CD microspheres constitute an environ-mentally friendly herbicidal formulation.

Automated summary

A novel photoresponsive herbicide delivery system was developed by functionalizing silica microsphere surfaces and encapsulating them with gamma-cyclodextrin. The microspheres showed remarkable loading capacity for pendimethalin and displayed excellent photoresponsiveness and controlled release. They exhibited longer duration weed control and lower genotoxicity than traditional pendimethalin, making them an environmentally friendly herbicidal formulation.