Degradable PDA@PNIPAM-TA Nanocomposites for Temperature- and NIR light-Controlled Pesticide Release

Adduct of Pesticide and Lignocellulosic Waste via Cleavable Silaketal Linkages for Agricultural Double Reduction

The abuse of hazardous agrochemicals leads to excessive toxic agricultural emissions, posing a tremendous threat to the natural surroundings and human well-being. In practice, the amount of pesticides in protecting crops is often far less than that lost into the environment through evaporation and leaching. Minimizing the use of pesticides as well as improving their use efficiency has been included in the policy of "agricultural double reduction," besides replacing the chemical fertilizer with straw returning. Here, we establish a strategy for controlling pesticide release from the lignocellulosic waste based on the stimulus-responsive cleavage of silaketal linkages. Noting that the cleavage of the silaketal linkages relies heavily on the substituent groups on silicon atoms, this pesticide-releasing system has the advantages of predictable service life and less environmental pollution in a desired time window. Instead of lengthy laboratory synthesis, outdoor instant synthesis can be conveniently realized with the help of a photothermal heating apparatus. After utilization, both silaketal linkages and lignocellulosic residuals are eco-friendly and can be a source of nutrients for soil. Referring to agricultural double reduction, this type of pesticide formulation is coined as a competitive approach to minimize pesticide pollution along with straw returning.

Redox/Near-Infrared Dual-Responsive Hollow Mesoporous Organosilica Nanoparticles for Pesticide Smart Delivery

Extremely inefficient utilization of pesticides has prompted a study of low-cost, sustainable, and smart application systems. Herein, as a promising pesticide nanocarrier, hollow mesoporous organosilica nanoparticles (HMONs) were first synthesized by using inexpensive CaCO3 nanoparticles as the hollow templates. A redox/near-infrared light dual-triggered pesticide release system was further achieved via loading avermectin (AVM) into the HMONs and coating a layer of polydopamine (PDA). The as-prepared AVM@HMONs@PDA displays a favorable pesticide load capability (24.8 wt %), outstanding photothermal performance, and high adhesion to leaves. In addition, with glutathione (GSH), the AVM cumulative release from AVM@HMONs@PDA was 3.5 times higher than that without GSH. Under ultraviolet light irradiation, the half-life of AVM@HMONs@PDA was prolonged by 17.0-fold compared to that of the AVM technical. At day 21 after treatment in the insecticidal activity, the median lethal concentrations (LC50) values displayed that the toxicity of AVM@HMONs@PDA for Panonychus citri (McGregor) was enhanced 4.0-fold compared with the commercial emulsifiable concentrate. In the field trial, at day 28 after spraying, AVM@HMONs@PDA was significantly more control effective than AVM-EC in controlling the P. citri (McGregor), even at a 50% reduced dosage. Moreover, HMONs@PDA was safe for crops. This research presents a novel preparation approach for HMONs, and it also offers a promising nanoplatform for the precise release of pesticides.