No abstract

A multifunctional nanomaterials based pesticide delivery system provides a powerful strategy for the efficient utilization of pesticides. We present here the application of a 2D MXene (Ti 3 C 2 ) nanomaterial for pesticide delivery and plant protection. Avermectin (AV), a hydrophobic and unstable insecticide, was chosen as the model pesticide. In our study, AV@Ti 3 C 2 was formed by fast adsorption of AV on Ti 3 C 2 , with a maximum loading capacity of 81.44%. Compared with hydrophobic AV, AV@Ti 3 C 2 exhibited significantly improved water solubility, which is beneficial for ensuring the bioactivity of pesticide. The AV@Ti 3 C 2 nanoformulation showed pH responsive slow-release behavior, overcoming the burst-release of conventional AV formulations. Besides, AV@Ti 3 C 2 possessed excellent photostability under UV irradiation, which prolonged the persistent period of AV. Therefore, AV@Ti 3 C 2 performed sustaining and enhanced antipest activity, according to the bioactivity assay. Furthermore, AV@Ti 3 C 2 showed satisfactory biosafety, with no negative effect to the germination and growth of maize. Our current research provides a potential candidate, AV@Ti 3 C 2 , for pest control, and also broadens the application of 2D MXene materials in plant protection and sustainable agriculture.

BACKGROUND Stimuli‐responsive pesticide controlled release system provides a new strategy for the development of high‐efficiency pesticides formulation. RESULTS In this article, we report a novel polydopamine surface modified MXene‐Ti3C2Tx nanocarrier for pesticide delivery and plant protection. Polydopamine modified Ti3C2Tx (PDA@Ti3C2Tx) nanocarrier was prepared by biomimetic self‐polymerization of dopamine on the surface of Ti3C2Tx. A typical pesticide, emamectin benzoate (EB), was loaded on PDA@Ti3C2Tx through physisorption process, with a high pesticide loading rate of 45.37%. PDA@Ti3C2Tx exhibited excellent photothermal conversion effect (η = 34.5%). Under the irradiation of near‐infrared (NIR) laser, EB would sustained release from PDA@Ti3C2Tx nanocarrier to surrounding medium. Compared with free EB, EB@PDA@Ti3C2Tx exhibited prolonged persistence period, which can keep antipest activity at 14 days post spraying. In addition, PDA@Ti3C2Tx nanocarrier and EB@PDA@Ti3C2Tx nanoformulation are of good safety, showing no side effect to the seed germination and seedling growth. CONCLUSION This research developed a novel nanocarrier for water‐insoluble pesticide delivery, realizing NIR‐responsive controlled release and sustained antipest activity.

A series of novel N‐substituted‐2‐(6‐morpholino‐9H‐purin‐9‐yl)acetamide and 4‐(9‐((5‐substituted‐1,3,4‐oxadiazole/thiadiazole‐2‐yl)methyl)‐9H‐purin‐6‐yl)‐morpholine derivatives were synthesized and evaluated their antibacterial activities against rice bacterial leaf blight and tobacco bacterial wilt caused by Xanthomonas oryzae pv. oryzae (Xoo) and Ralstonia solanacearum (R. solanacearum) via the turbidimeter test in vitro. Antibacterial bioassay indicated that most compounds demonstrated good inhibitory effect against Xoo and R. solanacearum. Especially, compound 6a demonstrated the best inhibitory effect against Xoo with half‐maximal effective concentration (EC50) value of 8.39 μg/mL, which was even better than those of commercial agents Bismerthiazol and Thiodiazole copper. The synthesized purine derivatives containing amide and 1,3,4‐oxadiazole/thiadiazole moieties exhibited excellent antibacterial activities against Xanthomonas oryzae pv. oryzae and R. solanacearum in vitro.

A series of novel 2-substituted methlthio-5-(4-amino-2-methylpyrimidin-5-yl-)-1,3,4-thiadiazole derivatives were synthesized, characterized and evaluated for antiviral activities against tobacco mosaic virus (TMV). The preliminary biological results indicated that most compounds exhibit excellent antiviral activity against TMV in vivo. Among these compounds, compounds 9c, 9i, and 9p displayed the similar curative effect against TMV (EC 50 = 287.05-322.47 μg/mL) to that of the commercial agent Ningnanmycin (EC 50 = 301.83 μg/mL). In particular, compound 9d demonstrated the best curative effect against TMV (EC 50 = 266.21 μg/mL), which was better than that of commercial Ningnanmycin.