Combination of modified biochar and polyurea microcapsules to co‐encapsulate a fumigant via interface polymerization for controlled release and enhanced bioactivity

Abstract

BACKGROUND Soil fumigants—the most effective agrochemicals for managing soil‐borne diseases—have been used extensively. However, high volatility, moderate toxicity and insufficient effective duration considerably limit their application. In the present study, interface polymerization was used to combine modified biochar (BC) and polyurea microcapsules (MCs) to co‐encapsulate allyl isothiocyanate (AITC), developing a model fumigant for controlled release (AITC@BC‐MCs). RESULTS The physical characteristics of BC modified by sand‐milling were significantly improved. In addition, chemical properties and morphological features of AITC@BC‐MCs characterized by integrated methods revealed successful preparation of BC‐MCs. Compared with monolayer MCs, BC‐MCs could significantly delay AITC release owing to the composite obstruction effect. Moreover, modifying BC endowed the cargo molecules with a pH‐responsive release property. Additionally, this composite showed a longer persistent duration by prolonging AITC degradation half‐life, which was 3.2–3.5‐fold greater than that of the AITC technical concentrate under different soil conditions. Finally, the control efficacy of the AITC@BC‐MC against pathogens, including nematodes and fungi, as well as against weeds was significantly enhanced at the same dose, but the composite did not inhibit seed germination and growth after 10 days when fumigated soil was aerated. CONCLUSION Construction of a composite encapsulation system enhanced pesticide efficacy, reduced dose via controlled release and delayed fumigant degradation in soil, indicating the great potential of this strategy for developing an effective and environmentally friendly fumigant formulation. © 2021 Society of Chemical Industry

Preparation, Characterization, and Bioactivity Evaluation of Lambda-Cyhalothrin Microcapsules for Slow-Controlled Release System

“…23,28 In curve b, the absorption peak at 2277 cm −1 was the stretching vibration of C�O in the polyurea formed by MDI and GT-34, indicating the successful formation of polyurea; similar results were reported before. 29 In curve c, the characteristic absorption peaks of technical lambda- cyhalothrin at 1728, 1587, and 1130 cm −1 can be found, and the characteristic absorption peak of polyurea was at 2277 cm −1 , which confirmed the formation of polyurea microcapsules and the successful loading of lambda-cyhalothrin.…”

“…Figure shows the FTIR spectra of the technical lambda-cyhalothrin, blank microcapsules, and lambda-cyhalothrin microcapsules. As shown in curve a, the absorption peaks at 3070, 1728, 1587, and 1130 cm –1 were attributed to the characteristic stretching vibration peaks of −CH 3 , CO, aromatic ring, and C–F, respectively, in technical lambda-cyhalothrin. , In curve b, the absorption peak at 2277 cm –1 was the stretching vibration of CO in the polyurea formed by MDI and GT-34, indicating the successful formation of polyurea; similar results were reported before . In curve c, the characteristic absorption peaks of technical lambda-cyhalothrin at 1728, 1587, and 1130 cm –1 can be found, and the characteristic absorption peak of polyurea was at 2277 cm –1 , which confirmed the formation of polyurea microcapsules and the successful loading of lambda-cyhalothrin.…”

Recent Advances in Nanoparticle-Mediated Co-Delivery System: A Promising Strategy in Medical and Agricultural Field

“…The release of the pesticide under UV light stimulation is 3.5 times that under natural light, demonstrating a good performance of light-controlled release of the smartly engineered pesticide. Ren et al used interface polymerization to combine modified biochar and polyurea microcapsules to co-encapsulate allyl isothiocyanate, developing a model fumigant for controlled release [ 101 ]. It shows potent bioactivity against soil-borne pathogens and weeds, and further minimizes fumigant usage.…”