An Alkali-Triggered Polydopamine Modified Mesoporous Silica Nanopesticide for Smart Delivery of Chlorpyrifos with Low Loss

The development of nanotechnology provides a feasible and effective way to reduce pesticide loss and improve pesticide utilization. In this study, we created chlorpyrifos-loaded mesoporous silica nanocomposites modified with polydopamine (Cpf-MSNs@PDA) for the smart control of pests. The release of Cpf from the nanocomposite was alkali triggered and temperature dependent, guaranteeing the sustained and steady effectiveness of the active constituent with prolonged persistence time. The modification with PDA endowed the nanocomposite with better foliar adhesion and rain erosion resistance. Compared with Cpf, the leaf slip angle of Cpf-MSNs@PDA was increased from 27° to 60°, and the rain erosion loss was reduced by 2.6 times. The insecticidal persistence of the Cpf-MSNs@PDA nanopesticide was measured and found to be better than that of commercial Cpf with bi-insecticidal pathways. In pathway 1, a small portion of Cpf (16.7%) was released from Cpf-MSNs@PDA in vitro to perform contact toxicity on Mythimna separata, which shows an advantage of sustained release. In pathway 2, after being ingested, the alkaline midgut microenvironment of M. separata triggered the degradation of Cpf-MSNs@PDA, inducing the release of all the Cpf to exert acute gastric toxicity. These results highlight the potential of a nanopesticide in the delivery of an active pesticide ingredient with low loss and high efficiency. The design of a smart nanocomposite for the control of a specific type of pest or disease provides ideas for the development of sustainable agriculture.