Imidacloprid-loaded mesoporous silica nanoparticles simultaneously coated with myristyl alcohol and polydopamine for NIR-triggered delivery on Aphis craccivora Koch.

The stimuli-responsive degradation of coating layer on pesticide-loaded mesoporous silica nanoparticles (MSNs) can realize on-demand release of pesticides. Herein, we report the simultaneously coating of imidacloprid (IMI)-loaded MSNs with phase change materials (PCMs) and polydopamine (PDA) to realize NIR-triggered release of IMI. To balance good thermal stability and sensitive thermal responsiveness, myristyl alcohol (MA) was selected as optimal PCM for IMI@MSNs@MA-PDA nanocomposites. The successful preparation of IMI@MSNs@MA-PDA nanocomposites was confirmed by FT-IR, small angle XRD, SEM, TEM, TGA and BET. MSNs@MA-PDA nanocomposites exhibited concentration and irradiation power dependent stable photothermal conversion ability, with the maximum temperature increase of 23.3 ℃ (808 nm, 2 W/cm, 300 μg/mL). The drug loading and encapsulation efficiency of IMI were 30.1% and 43.0%, respectively. The cumulative release of IMI from IMI@MSNs@MA-PDA was increased by ∼30% when the temperature was increased from 25 ℃ to 38 ℃. Meanwhile, initial burst release of IMI from MSNs was inhibited. Finally, in vivo insecticidal activity of IMI@MSNs@MA-PDA was evaluated on Aphis craccivora Koch. The LC value was decreased from 5.01 mg/L to 3.73 mg/L, resulted from photothermal-boosted release of IMI. Our facile and effective method to prepare MSNs-based photothermal-responsive pesticide delivery system can be generalized to prepare other nanomaterials-based delivery systems for efficient and eco-friendly pesticide-control in agriculture.